SELF-REGULATING POSITIVE TEMPERATURE COEFFICIENT ELECTRICAL HEATING ELEMENT

摘要

This invention relates to self-regulating heating elements having one or more PTC resistors enveloped by a synthetic-material/filler mixture which has a good heat conductivity, such as an MgO-S102-silicon rubber mixture, and which is able to withstand the highest operating temperature. Such resistors have usually consisited of sintered barium titanate doped with rare earth or other elements, and have been limited as to the power consumed and dissipated as heat. Heating elements filled with liquid have in addition problems associated with leaking. This invention utilizes improved heat dissipation to increase the consumable power, since the PTC resistors reach the Curie point only at a larger power output. Moreover, the PTC resistor and the outside of the casing is relatively small enabling use of PTC resistors having a lower Curie point. This is enhanced further through use of a cylindrically-shaped casing.