Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2001-07-13
2003-04-22
Paik, Sang (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S447100
Reexamination Certificate
active
06552307
ABSTRACT:
The invention relates to a temperature detection device for an electric radiant heater, with which is associated an active sensor for the detection, of the positioning of a cooking vessel on a hotplate covering the radiant-heater and in particular a glass ceramic plate.
The automatic switching on and off of a cooking point as a direct function of the placing thereon of a cooking vessel or pot has been a long-term aim. The systems proposed for this purpose are based on the most varied principle and usually the nature and arrangement of the sensor for detecting the cooking vessel positioning is decisive. In the inductive systems considered in preferred manner here, the sensor is part of an inductive resonant circuit of a control means, preferably operating by means of resonant circuit tuning, and has at least one sensor loop with electrically conductive material through which an inductance is formed. The sensor loop is positioned in the vicinity of at least one heating zone heatable by electric radiant heating elements in such a way that through a cooking vessel positioned in the vicinity of the heating zone the inductance of the sensor loop is modified in such a way that a connected evaluating device can distinguish between the presence and absence of a set down cooking vessel.
A simple and robustly constructed pot detection system of this type, which supplies particularly significant signals for the control of the radiant heater is disclosed by DE 196 03 845. A temperature detection device for the radiant heater therein comprises a temperature monitor with a rod-like temperature sensor, which acts on a temperature monitor contact for maintaining a permitted material temperature on the underside of the glass ceramic hotplate and on a hot indication contact for indicating the hot state of the heater. The rod sensor projects through an insulator rim laterally bounding the heating zone and passes in a plane above the radiant elements below the sensor loop.
The problem of the invention is to provide a temperature detection device for such radiant heaters, which is particularly simple and inexpensively manufacturable.
This problem is solved by a temperature detection device having the features of claim 1. Preferred further developments are given in the dependent claims, whose wording is by reference made into part of the content of the description.
According to the invention the sensor loop has at least one portion, which is functionally part of a temperature sensor, which emits temperature signals, of the temperature detection device, the temperature signals preferably being electrical and/or are electrically or electronically evaluatable. The presence of a sensor loop for pot detection purposes is consequently utilized in order to ensure an adequately precise temperature detection with the aid of the sensor loop. Use is made of the fact that the sensor loop is generally located in the vicinity of a heating zone and preferably also in the immediate proximity of the hotplate, particularly glass ceramic plate, whose temperature is to be monitored. This favourable positioning of the sensor loop or its portion used for temperature detection purposes makes it possible, particularly in conjunction with appropriately selected electrical and/or structural characteristics of the portion or the sensor loop, to integrate an effective temperature detection device with the pot detection sensor system. Thus, there is no need for separately provided temperature detection devices, such as e.g. the aforementioned rod sensors.
A further development is characterized in that the sensor loop at least partly overlaps the heating zone with at least one overlapping portion and the portion used as the functional part of the temperature detection device is preferably located in the vicinity of the overlapping portion. As a result the portion used for temperature detection purposes is located directly in the radiant area of the radiant elements and preferably spaced from an insulating edge bounding the heating zone. This permits a particularly short delay temperature detection or temperature change detection with optionally only small temperature variations. This arrangement also leads to advantages for the pot detection function, because a pot detection signal provides much more information for the covering of the heating zone as compared with a sensor passing round in the marginal area of the heater and consequently is more significant for pot detection purposes. The relevant explanations in DE 196 03 845 are hereby, by reference, made into part of the present application.
Within the scope of the invention various appropriate use possibilities of the sensor loop exist for temperature detection. For example the situation can be such that the temperature detection device has an electronic device for evaluating electrical temperature signals and that said device is in signal-conducting, electrical connection with the portion of the sensor loop. The portion can here form an electrically active part of the temperature sensor, so that temperature-dependent, electrical characteristics of the portion, optionally in conjunction with the temperature-dependent, electrical characteristics of neighbouring portions, can be used for producing temperature signals.
The situation can e.g. be such that the device for evaluating temperature signals is constructed for detecting and evaluating thermally caused changes in the electrical resistance of the portion, the complete sensor loop or a resistance element carried by the sensor loop, e.g. a resistance wire or a resistive film. For producing very readily evaluatable temperature signals the material, whose resistance is used for temperature detection purposes, is appropriately provided with a high temperature coefficient of the electrical resistance and said temperature coefficient can be both positive (PTC) and negative (NTC).
It is also possible for the sensor loop with at least one loop portion to form part of a temperature sensor functioning as a thermocouple. A connected signal processing is then appropriately provided for the processing of thermoelectric voltages and can assume any appropriate form for this.
The construction of at least one thermocouple with the aid of the sensor loop or one of its portions can take place in different ways. For example, the sensor loop can have a first loop portion of a first electrically conductive material and a second loop portion, contacted therewith, of a second electrically conductive material, said first and said second materials having different contact potentials in the contact series. The contact point is appropriately located in the vicinity of a preferably provided overlapping portion, i.e. is directly subject to the radiant energy of the radiant heater. An advantage of this variant is its simple construction, because apart from the sensor loop no additional elements are required. The thermoelectric voltage can simply be tapped at appropriate points of the resonant circuit embracing the sensor loop.
For forming a thermocouple it is also possible to provide at least one preferably filamentary material portion, which is made from an electrically conductive material with an electric contact potential different from the loop portion material and which is electrically conductively connected to the loop portion in the vicinity of a contact point and is more particularly welded thereto. In this case one thermocouple side is formed by the loop portion, whereas the separate material portion fitted thereto forms the other side. The thermoelectric voltage is then tappable between the end of the material portion and one end of the sensor loop. For forming a thermocouple with two contact areas, it is also possible to provide two preferably filamentary material portions of electrically conductive material, which are electrically conductively connected in spaced manner with a loop portion in the vicinity of the contact points and are more particularly welded, the two material portions being made from materials with different electric cont
Gremm Oliver
Perrin Wilhelm
Schilling Wilfried
Akerman & Senterfitt
E.G.O. Elektro-Geraetebau GmbH
Paik Sang
LandOfFree
Temperature detection device for an electric radiant heater does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temperature detection device for an electric radiant heater, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature detection device for an electric radiant heater will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3048446