Utensil removal detection system for cooking appliance

A utensil removal detection arrangement for a cooking appliance having at least one surface heating unit for heating a utensil placed thereon and including user operable switch means for turning the surface unit ON and OFF, said detection arrangement comprising:

• temperature sensing means for sensing the temperature of a utensil placed on the surface unit;
• means responsive to said temperature sensing means operative to detect a utensil temperature greater than a predetermined reference temperature;
• latch means responsive to said temperature detection means operative to assume a first state upon the first detection following the turning ON of the surface unit of a utensil temperature greater than said reference temperature and to assume a second state upon the switching OFF of the surface unit;
• clock means responsive to said temperature detection means operative to time the duration of time intervals during which the sensed utensil temperature is less than said predetermined reference temperature;
• means responsive to said clock means and said latch means, operative to detect time intervals greater than a first predetermined duration when said latch means is in its second state and to detect time intervals greater than a second predetermined duration less than said first predetermined duration when said latch means is in its first state;
• and
• means responsive to said time detection means operative to de-energize the heating unit upon detection of such time intervals.

A utensil removal detection arrangement for a cooking appliance having at least one surface unit for heating a utensil placed thereon, and user operable input means enabling the user to select a plurality of operating modes and a plurality of heat settings for each mode, including OFF, said pan removal arrangement comprising:

• temperature sensing means for sensing the temperature of a utensil placed on the surface unit;
• means for detecting a sensed utensil temperature greater than that one of a plurality of predetermined reference temperature associated with the particular selected mode and heat setting;
• clock means responsive to said temperature sensing means operative to time the duration of time intervals during which the sensed utensil temperature is less than the predetermined reference temperature for the selected mode and heat setting;
• latch means responsive to said temperature means and the user operable input means operative to assume a first state following a change in mode or change to a higher heat setting upon the first detection of a sensed utensil temperature greater than the reference temperature for the newly selected heat setting;
• and to assume a second state upon a change in setting to a lower setting or selection of the OFF setting;
• means responsive to said clock means and said latch means operative to detect a time interval greater than a first predetermined reference time when said latch is in its second state, and to detect a time interval greater than a second predetermined reference time interval when said latch is in its first state, said second predetermined reference time being less than said first predetermined reference time;
• and means responsive to said time detection means operative to de-energize the surface unit upon detection of such a time interval.

In a cooking appliance having at least one surface unit for heating a utensil placed thereon, user operable input selection means enabling the user to select from a plurality of operating modes including Boil and Fry Modes and a plurality of heat settings for each mode, including OFF, each heat setting for each mode having associated with it a predetermined minimum steady state reference temperature, a utensil removal detection arrangement comprising:

• temperature sensing means for sensing the temperature of a utensil placed on the surface unit;
• means for detecting a sensed utensil temperature greater than the predetermined reference temperature associated with the selected mode and heat setting;
• clock means responsive to said temperature detecting means operative to measure the duration of time intervals during which the sensed utensil temperature is less than said predetermined reference temperature for the selected mode and heat setting;
• latch means responsive to said temperature detection means and the input selection means, operative to assume a first state upon the first occurrence of a sensed utensil temperature greater than said associated reference temperature following a change in heat setting from a lower heat setting to a higher heat setting and to assume a second state upon a change from a higher setting to a lower setting;
• means responsive to said clock means and said latch means operative when said latch means is in its first state to de-energize the heating element when the sensed utensil temperature remains less than said associated reference temperature for a time interval greater than a first predetermined reference time, and operative when said latch means is in its second state to de-energize the heating element when the sensed utensil temperature remains less than said associated reference temperature for a second predetermined reference time, said second reference time being less than said first reference time.