Temperature self regulating heaters and soldering irons
First Claim
1. The method of adapting a Curie point self regulating heater for use at frequencies materially lower than that for which it was designed, such Curie point self regulating heater providing a core having a working end, said core having a region displaced from the working end of the core, said core being of a thermally and electrically conductive, paramagnetic material and a layer of about 1.8 to 2 skin depths of ferromagnetic material on an outer surface of the region of the core displaced from the working end and having an effective Curie temperature at approximately the desired temperature of regulation and a coil comprising layers of windings located adjacent said region of the core to excite the ferromagnetic material, the coil designed for operation at a frequency of 13.56 MHz, the method of adaptation to operation at a materially lower frequency comprisingincreasing the thickness of the layer of ferromagnetic material on said region to a thickness of approximately 2.5 to 3.5 skin depths at a materially lower frequency than 13.56 MHz,increasing the axial length of the coil along said region to achieve an electrical circuit of resistance approximately equal to that of the higher frequency heater,increasing the length of the core to accommodate the increased length of the coil, andincreasing the cross-sectional area of the core adjacent the coil to provide adequate heat transfer from the core adjacent the region of the coil most remote from the working end of the core to maintain the heater temperature within a prescribed temperature range for the heater in the presence of varying loads.
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Accused Products
Abstract
A Curie point heater primarily for use in a soldering iron and initially designed to operate with currents in the megahertz range is restructured to operate in the kilohertz range. Further in one embodiment of the heater, the coil exciting the heater is mounted in the handle of the iron.
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Citations
15 Claims
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1. The method of adapting a Curie point self regulating heater for use at frequencies materially lower than that for which it was designed, such Curie point self regulating heater providing a core having a working end, said core having a region displaced from the working end of the core, said core being of a thermally and electrically conductive, paramagnetic material and a layer of about 1.8 to 2 skin depths of ferromagnetic material on an outer surface of the region of the core displaced from the working end and having an effective Curie temperature at approximately the desired temperature of regulation and a coil comprising layers of windings located adjacent said region of the core to excite the ferromagnetic material, the coil designed for operation at a frequency of 13.56 MHz, the method of adaptation to operation at a materially lower frequency comprising
increasing the thickness of the layer of ferromagnetic material on said region to a thickness of approximately 2.5 to 3.5 skin depths at a materially lower frequency than 13.56 MHz, increasing the axial length of the coil along said region to achieve an electrical circuit of resistance approximately equal to that of the higher frequency heater, increasing the length of the core to accommodate the increased length of the coil, and increasing the cross-sectional area of the core adjacent the coil to provide adequate heat transfer from the core adjacent the region of the coil most remote from the working end of the core to maintain the heater temperature within a prescribed temperature range for the heater in the presence of varying loads.
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7. A Curie point self-regulating soldering iron comprising
a tip for the soldering iron with a rearward extension of an electrically and thermally conductive material, a layer of ferromagnetic material on said rearward extension having a thickness of approximately 2.5-3.5 skin depths at the frequency of operation, said ferromagnetic material and said highly conductive rearward extension constituting a heater, an electrically conductive coil for exciting said heater, said coil having a number of turns to produce a system resistance sufficient to rapidly heat said tip to a temperature approaching the effective Curie temperature of said layer consequently reducing the iron'"'"'s temperature, and a sleeve of ferromagnetic material, an end wall for said sleeve, said end wall disposed between said coil and said tip, substantially in contact with both said coil and said tip and having an aperture to receive said rearward extension.
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15. A coilless Curie point temperature self regulating soldering iron cartridge adapted to be used with a handle having an induction coil therein, said cartridge comprising;
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a heatable tip, a ferromagnetic material of a desired Curie point disposed on said cartridge rearwardly of said tip, means disposed on said cartridge to insure alignment of said ferromagnetic material with an induction coil in the handle for energizing said ferromagnetic material to cause its temperature to approach its Curie temperature sufficiently to reduce heating, and means disposed on said cartridge to permit said cartridge to be securely maintained in alignment with the induction coil.
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Specification
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- Resources
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Current AssigneeDelaware Capital Formation Incorporated (Dover Corporation)
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Original AssigneeMetcal Incorporated (Dover Corporation)
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InventorsDaniel, Steven A., Cowell, Mark J.
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Primary Examiner(s)Leung, Philip H.
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Assistant Examiner(s)Mills, Gregory L.
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Application NumberUS07/925,029Time in Patent Office706 DaysField of Search219/10.75, 219/10.77, 219/10.41, 219/10.43, 219/227, 219/229, 219/230, 219/233-241, 219/9.5, 219/10.491, 219/85.11, 219/10.79US Class Current219/616CPC Class CodesB23K 3/0475 using induction effects, e....
