Abstract: Device for induction heating of cooking receptacles, of the type comprising at least two concentric induction coils supplied by a generator. Each induction coil (I.sub.1, I.sub.2, I.sub.3) is supplied by a separate generator (G.sub.1, G.sub.2, G.sub.3), the number of induction coils being equal to the number of supply generators. A control block (8) effects the independent operation of each supply generator (G.sub.1, G.sub.2, G.sub.3). The control block (8) is adapted to cause to operate according to a sequential order the supply generators (G.sub.1, G.sub.2, G.sub.3) during a detection step of the presence of a load on the corresponding induction coil (I.sub.1, I.sub.2, I.sub.3), starting with the generator (G.sub.1) corresponding to the innermost concentric induction coil (I.sub.1) and progressing to the outermost concentric induction coil covered by the receptacle (9) to be heated. The supply generators (G.sub.1, G.sub.2, G.sub.

Abstract: An appliance control circuit comprising dual processor control for enhanced control operation and agency safety redundancy. A first processor is disposed in operative communication with operator control switches for primarily controlling the supply of power for principal appliance functions. A second processor is in operative communication with the first processor and disposed for primarily monitoring appliance safety detection circuits and for controlling agency circuitry redundancy through a second switch in series with the first switch. The first and second switches comprise agency circuitry for enabling said supply of power when said first switch is directly enabled by the first processor and the second switch is directly enabled by the second processor for safety redundancy of said power supply.

Abstract: An induction heating generator is described for braze-welding metallic pipes with a continuous process under a controlled atmosphere, comprising at least one heating inductor composed of two half-inductors in series whose winding directions for their windings are one opposite to the other. The generator is further equipped with a quartz tube placed inside the inductors and in which the metallic pipes pass together with the controlled atmosphere gas. The generator further includes at least one removable sealing insert to join two contiguous inductors. For every medium- and/or high-frequency section of the generator, a load matching system is finally provided to compensate for external diameter variations of the pipes, the system being interlacedly handled by a programmable controller (P.L.C.).

Abstract: A heating system and method for heating a metal strip to within a predetermined temperature tolerance range while the metal strip serially travels through a heating system. The heating system has at least one preceding heating section, at least one induction heating section, and at least one following heating sections, with the heating sections being serially arranged. The metal strip is heated to below the Curie point of the metal strip in the preceding heating section. Next, the metal strip is heated to, at a maximum, approximately the Curie point in the induction heating section. Then, the metal strip is heated to above the Curie point and to within the predetermined temperature tolerance range in the following heating section.

Abstract: A control device particularly for induction cooking ranges with multiple heating units which comprises a plurality of induction coils. The induction coils can be electrically parallel-connectable to each other. The device also comprises elements for engaging the induction coils connecting individual induction coils or pairs of induction coils to a single electric power converter, and elements for sensing the presence or the absence of a pot or the presence of an unadapted pot on a particular induction coil; the sensor elements are electrically connected to control means that select, on user's command, the induction coils to be activated and the power to be carried to each individual induction coil, and control the sending of shares of the power generated by the electronic converter to each active induction coil, at the same time limiting the periodic variations in the current absorbed from the mains, within the limits allowed by statutory provisions regarding so-called "flicker".

Abstract: The load balancer incorporates link coil circuits that inductively couple to induction heating coils, which are connected in parallel across a power source. A capacitor is electrically connected in the link coil circuit. By varying degree to which the link coil is inductively coupled to the heating coil or by changing the capacitance, either using a variable capacitor or switching among different capacitors, changes in the amount of reactance coupled into the heating coil are effected. Thus, the current in the corresponding heating coil can be varied, enabling adjustment of the heating of the workpiece. Accordingly, the resulting system is efficient since only a single coil rather than multiple series coils are used. This aspect can be enhanced when litz cable is used in coil construction. Further, the system is compatible with active control.

Abstract: A method and apparatus for sensing the temperature of a susceptor in a bond line in an inductive welding process utilizing a conductive susceptor at the interface between the two plastic parts, and a magnetic coil that generates an alternating magnetic field and projects the field through the parts and around the susceptor. As the susceptor gets hot, its electrical resistance changes as a function of the thermal coefficient of resistance of the susceptor material, and that change of resistance is reflected back as a change in the drive coil impedance. An electrical circuit senses the varying resistance and that change in resistance is translated into a change of temperature on a temperature display, and may be used to adjust the power to the work coil or the speed of travel of the work coil along the bond line. The circuit includes a high power bridge with a sensitive null arm to sense changes in the susceptor impedance due to temperature changes.

Abstract: A control system for controlling overshoot and undershoot power values when switching power from a single inverter power source to a plurality of inductive loads, or a single load having a plurality of zones, having different resonant frequencies. The control system causes a preselected amount of power to be drawn from the inverter power source and delivered to the loads, or zones in a time-shared manner. The control system varies the phase shift between load voltage and load current and selectably adjusts the amount of variation in response to overshoot and/or undershoot of power drawn from the inverter and delivered to a load or zone which can occur when switching between loads or zones.

Abstract: Induction heating apparatus for heating an elongate metal workpiece of predetermined width generates time varying magnetic fields which produce longitudinal eddy current distributions across the width of the workpiece having cosine and sine profiles. The amplitude of these profiles is not necessarily uniform across the width of the workpiece and the spatial period of these profiles across the workpiece width are chosen to ensure that the line integral across the workpiece of the eddy currents is zero. In this way a desired heating profile across the width of the workpiece can be maintained.

Abstract: In a method for open-loop/closed-loop control of current converter valves of at least two load-guided parallel oscillating circuit inverters being supplied from a common direct current or direct voltage source and being connected in series on the DC side, each inverter has one induction furnace with a compensating conductor. Two diagonally opposed current converter valves are ignited at a time in one inverter to establish a flow of current from the source with a series-connected choke through the parallel oscillating circuit connected to that inverter. Load phase angles of the parallel oscillating circuit inverters are adjusted, resulting in arbitrarily specified individual powers of the parallel oscillating circuits wherein a maximum power that can be output by the source is taken into account, and attaining a specified ratio between the individual powers of the parallel oscillating circuits.

Abstract: A method and a system for heat treating an impact beam of an automotive vehicle door. Hot rolled steel sheets are prepared having a composition consisting essentially of 0.18% to 0.22% carbon; 1.0 to 1.5% manganese; 0.15 to 0.4% silicon; not more than 0.025% phosphorous; not more than 0.008% nitrogen; not more than 0.0010% sulfur; 0.01 to 0.04 aluminum; 0.001 to 0.003% boron; 0.1 to 0.3% chromium; 0.01 to 0.035% titanium; and the balance essentially iron, roll-forming and welding the steel sheets to make a tube-shaped impact beam. The heat treatment is carried out by high frequency induction heating and air cooling the impact beam, and water cooling the heat treated and air cooled impact beam.

Abstract: A dual push-pull heating device of induction cooker having multiple burners is provided with a microprocessor controlling a logic amplifying drive circuit outputting a high-frequency pulse signal, so as to drive alternately at least a power element or power transistor having two parallel electromagnetic induction coils arranged at an end thereof in such a manner that a common end of said induction coils is connected with a common connection point of a relay whose normal close point is connected with a non-common end of one of the induction coils and whose normal open point is connected with a non-common end of another one of the induction coils.

Abstract: Induction heating apparatus, typically for metal melting, with multiple zone temperature control has an induction coil (10) divided into individual sections (10a, b, c) associated with respective zones and powered in parallel under regulation from controller (20) as shown in FIG. 1. To give precise and efficient automatic regulation of the zone temperatures the power supply is provided by a resonant invertor (14) as a medium frequency pulsed output and at an instantaneously selected level which is the sum of the power requirements of all the zones at any instant, and the average power applied in each zone is controlled by pulse width modulation with switching to high power for a proportion, determined by demand in that zone, of each of successive standard time periods.