Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2002-08-16
2003-06-17
Paik, Sang (Department: 3743)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S459100
Reexamination Certificate
active
06580058
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a cooktop or hob with a cooktop panel, beneath which at least one heating element is disposed for heating up a cooking vessel that can be placed on the cooktop panel, and with a temperature sensor for sensing the temperature of the cooktop panel, and also relates to a corresponding heating element and a suitable element.
German Patent DE 37 03 768 C2, corresponding to U.S. Pat. No. 4,851,645 to Wolf et al. discloses a cooktop having a device for sensing the temperature of a glass-ceramic panel heated up by heating windings or halogen lamps with a temperature sensor. The sensor emits a signal corresponding to the temperature of the glass ceramic for a control circuit. The heating windings or halogen lamps are disposed in the interior space of a cup-like insulating base and heat up the glass-ceramic panel by direct radiation. The edge of the insulating base bears under resilient stress against the underside of the glass-ceramic panel, and the temperature sensor is disposed outside the interior space of the insulating base, but within the heating element. The temperature sensor is also in heat-conducting connection with the underside of the glass-ceramic panel, the temperature sensor being disposed in a receptacle in the edge of the insulating base. The receptacle is disposed at a distance x from the inner side of the edge of the insulating base, the minimum value of which is chosen such that the brief temperature changes arising when the heating windings or halogen lamps are switched on and off have only a negligible influence on the temperature sensor. The maximum value of the distance x is chosen such that the delay caused by the thermal conductivity of the glass-ceramic panel produces a small hysteresis in the control characteristic. Widths of from 3 mm to 6 mm have proven to be advantageous as the distance x. The temperature sensor is fitted in the receptacle that has been made or pressed into the upper side of the attachment that protrudes into the interior space of the insulating base, and is in heat-conducting connection with the underside of the glass-ceramic panel. The temperature sensor is held indirectly under resilient stress against the underside of the glass-ceramic panel, to keep the heat transfer resistance between the glass-ceramic panel and the temperature sensor small.
Furthermore, European Patent Application EP 0 021 107 A1 discloses a heating element for a cooking unit with a temperature sensor. To maintain complete heating of the entire surface area of the heating element, and, nevertheless, couple the temperature sensor of the controller closely to the heating device, a heat-transfer element in the form of a metal sheet is used, the sheet being disposed between the heating elements and the glass-ceramic panel such that it partly covers the heated region, but protrudes from the heating element and is in connection there with the temperature sensor of the controller. The heat-transfer element is fastened by secure clamping on the edge of the shell carrying the heating device and normally bears against the underside of the glass-ceramic panel. An outer portion protrudes from the heat-sensing region of the heat-transfer element outward beyond the edge of the heating element. It is formed in one piece with the aforementioned region, is substantially parallel to the latter, but offset downward somewhat by a bend, so that the outer portion does not bear against the underside of the glass-ceramic panel. The sensor cell of the temperature sensor is pressed by a compression spring against the underside of the heat-transfer face of the heat-transfer element, which is supported on a holding mechanism that guides the sensor cell and is attached to the outer portion of the heat-transfer element. However, other types of sensor and ways of attaching it are also possible. For example, an electrical NTC or PTC sensor, which is pressed resiliently into contact or securely attached to the outer portion of the heat-transfer element, may also be used. The transfer element can be grounded if desired, providing protection against electric shock.
Furthermore, the U.S. Pat. No. 4,447,710 to McWilliams discloses a glass-ceramic cooktop in which an insulator on which a temperature sensor, for example, a thermocouple, is mounted is disposed in the edge region of the heating element. The thermocouple is kept in good thermal contact with the underside of the glass-ceramic panel by the insulating block.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a cooktop with temperature sensor and a corresponding heating element that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that has good measuring accuracy while being easy to fit.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a cooktop, including a cooktop panel having an underside, at least one heating element disposed beneath the cooktop panel for heating up a cooking vessel to be placed on the cooktop panel, the at least one heating element having an inside, a control unit electrically connected to the at least one heating element for controlling a heating power of the at least one heating element, a temperature sensor sensing a temperature of the underside of the cooktop panel within the at least one heating element, the temperature sensor electrically connected to the control unit, an element extending from the inside of the at least one heating element to a region outside the at least one heating element, the element having at least one of a receiving portion disposed at the inside of the at least one heating element and receiving the temperature sensor, a fitting portion for fastening the element to the at least one heating element, and a connection portion to be connected to an electrical line disposed outside the at least one heating element, the receiving portion being radially offset laterally with respect to one of the fitting portion and the connection portion, and the temperature sensor fastened to the element.
The invention provides a cooktop in which the temperature sensor is fastened to an element that extends from a region inside the heating element into a region outside the heating element, the element has a receiving portion inside the heating element for the temperature sensor and a fitting portion for the fastening of the element, in particular, to the heating element, and/or a connection portion for the connection at least of an electrical line respectively outside the heating element, which receiving portion lies radially offset laterally with respect to the fitting portion or connection portion. According to the invention, a corresponding heating element and also an element for the heating element are further provided. Due to the construction according to the invention, the relative position of the temperature sensor with respect to the element and their heat-conducting behavior can be precisely fixed and a structural unit that can be pre-assembled and pre-tested and is also easy to handle technically in terms of assembly/fitting, because it is quite large, is provided. When fitting the configuration on the heating element, it only remains to ensure error-free fastening of the heat-conducting element to the heating element. The thermal coupling of the heat-conducting element to the underside of the cooktop panel within the heating element and the simultaneous fastening of the temperature sensor to the element have the effect that the temperature sensor is optimally coupled to the cooktop panel or to a cooking pot placed thereon, while also being easy to position and easy to fit.
In accordance with another feature of the invention, the temperature sensor is disposed in the region of a temperature limiter of the heating element. As a result, on one hand, all the electrical connections can be disposed spatially together in a way that is favorable technically in terms of assembly/fitting and, on
Grätz Franz
Has Uwe
Neumayer Dan
Theine Markus
Vetterl Peter
BSH Bosch und Siemens Hausgeräte GmbH
Paik Sang
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