Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-12-12
2002-06-11
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S490000, C219S494000
Reexamination Certificate
active
06403929
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for sensing overheating of a food container in accordance with the introduction to the main claim. The invention also relates to a device for implementing the method.
2. Description of the Related Art
Various methods are known for controlling components of a glass ceramic cooking hob, such as the heating elements associated with it or the glass ceramic surface on which the food containers rest. For example, EP0886459 describes and claims a method and device for controlling the heating elements (ie their electrical supply and hence the heating power generated by them) of a cooking hob of the aforesaid type in order that the temperature of the glass ceramic surface does not exceed a predetermined safety value.
With the known solutions and methods, the heating elements are controlled on the basis of measurement of the temperature of the glass ceramic surface. Using this measurement (effected by usual sensors which directly or indirectly measure the temperature of the glass ceramic surface), a heating element control unit successively activates and deactivates the elements in order to maintain said glass ceramic surface temperature within safety limits. The manner in which this cycle of successive activations and deactivations (which lasts from the moment in which a user switches a heating element on until he switches it off) is implemented means that said surface reaches temperatures which differ considerably (by 30-40° C.) from the measured temperature. Consequently, even though the known methods enable the temperature of this surface to be maintained within safety limits, they do not allow the temperature to be instantly and precisely controlled at each moment of use of the cooking hob for food preparation.
It has been surprisingly found that the temperature of the glass ceramic surface is also related to any overheating of a food container positioned on it during food preparation. In particular, it has been found that the absence of liquid in a container positioned on a region of said surface corresponding to an active heating element results in a sudden and considerable increase in the surface temperature to well beyond the safety limit, with obvious problems and consequences for the mechanical stability and average life of the glass ceramic cooking hob. This sudden temperature increase has hence been found to arise on overheating of the container.
The known heating element control methods and devices operating on the basis of the temperature of the glass ceramic surface do not adequately detect container overheating or act sufficiently quickly on the heating elements, as they control these elements only by cyclic temperature measurement and act on these elements only at relatively lengthy time intervals corresponding to temperature limits relatively very far apart (for example 30-40° C.). If a container on the cooking hob were to undergo sudden overheating during one of these activation and deactivation cycles, known devices would sense this only with considerable time delay.
Moreover, although said devices are able to limit the temperature of the glass ceramic after a user has switched a heating element on, they are not able to automatically switch the heating element off if the temperature exceeds or remains above a predetermined limit.
SUMMARY OF THE INVENTION
An object of the invention is therefore to provide a method for measuring and interrupting the overheating of a food container if its contents are lacking or depleted, said method being reliable and resulting in a rapid solution to the said overheating problem, with prevention of any irremediable effect at least on the cooking hob.
A further object is to provide a device for implementing the aforesaid method which is of simple construction and reliable with time.
These and further objects which will be apparent to an expert of the art are attained by a method and device in accordance with the accompanying claims.
REFERENCES:
patent: 4740664 (1988-04-01), Payne et al.
patent: 5430427 (1995-07-01), Newman et al.
patent: 5856654 (1999-01-01), Frasnetti et al.
patent: 5900174 (1999-05-01), Scott
patent: 5951897 (1999-09-01), Wauer et al.
patent: 6246034 (2001-06-01), Glaser et al.
Krefman Stephen
Paik Sang
Rice Robert O.
Van Winkle Joel M.
Whirlpool Corporation
LandOfFree
Method and device for sensing overheating of a container... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for sensing overheating of a container..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for sensing overheating of a container... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2982415