DE1004305B - High-frequency furnace with a grid-controlled electron tube oscillator - Google Patents

Description

This automatic regulation prevents 15
be that with overload and in particular also
in the event of underloading, possibly idling, of the device, the grid circuit of the generator tube is overloaded; this is where the regulation that occurs is based
on a change in the grid direct current, whereby 20
under normal load the load on the grid circle
lower than permissible.

The invention provides such an improvement

such a device for heating work- Lourens Blök, Gerrit Starre, Gooitzen Zwanenburg

pieces with automatic adjustment of the excitation, 25 and Jacob Willem de Ruiter, Eindhoven (Netherlands),

Representative: Dipl.-Ing. K. Lengner, patent attorney,
Hamburg 1, Mönckebergstr. 7th

Claimed priority:
Netherlands from April 18, 1951

have been named as inventors

that the oscillator tube under all practical operating conditions receives the same, maximum permissible excitation voltage, with the feedback

by an electromagnetic spring pressure 2

the controller automatically adjusts to the optimum value

is regulated. speaking, the spring tension characteristic must be equal to

According to the invention, in order to achieve one, are square.

Asian regulation, the curve, which is based on Although any known spring construction

magnetically exerted on the regulating element with a quadratic spring tension force due to the grid slip current in the case of an application characteristic curve in a device after which almost the maximum permissible excitation of the oscillator can be used. To use a spring construction, which adjusts from one, and the curve, which consists of the leaf spring clamped on both sides of the regulating element, whose free, influencing spring tension presses against the regulator according to the end of the regulation and is a mirror image of one another Pinch point and the point of contact with the regulator with respect to the axis along which the outer organ of the regulator is removed along the spring adjusting screw stop, so that the regulating organ is independent, against which an equilibrium position of the regulator arises when the regulator deflects, depending on its deflection the spring in turn le gt,
can take. At this point it should be noted that the general

When applying the invention has for each 45 principle of astatic controllers per se z. B. from the Point of the control range of the device between beech "The automatic control" by A.Leonhard

is known. Applying this principle to a High-frequency furnace with a grid-controlled electron tube oscillator however, it has special effects and benefits.

The invention and its merits are on hand

No-load and full load, the excitation voltage occurring in the grid circuit has a value such that the Oscillator works under the most favorable operating conditions.

In the normal formation of the magnetic circuit with the regulating organ, the runs on the regulating organ The square of the curve representing the force of attraction exerted by a magnet. Demented

an embodiment shown in the drawing explained in more detail. Corresponding parts are in the Figures are provided with the same reference numerals.

609 839/331

3 4

Fig. 1 shows the basic circuit diagram of a device bengewinde provided, made of soft iron according to the invention; cylindrical core is screwed into opening 21 '. Of the Individual part of an advantageous embodiment of the core 22 is provided with an axial bore. In Device according to the invention, and 5 of the other opening 21 of the yoke is the regulating member 3 shows schematically a further individual part; 15 displaceable, the one facing the core22 Fig. 4 shows characteristics to explain the invention end with a z. B. made of brass pin manure; . 23 is verseihen, the ver-Fig. 5 shows a simplified circuit of a push-in device. The end of the pin 23 works together according to the invention, which is particularly in ver io men with a leaf spring 16 and is also in their relatively low performance, e.g. B. up to 10 kW, free end stored. At the other end the sheet is used can be. spring attached to the mounting plate 19 by a In the circuit according to FIG. 1, the high frequency support bracket 24 is clamped. To have a smooth That is to say, to achieve a grid-controlled electron centering of the regulating organ with the help of a lattice-controlled electron tube oscillator with a triode 1 taken. At the other end of the regulating organ, there is also an anode circuit in one formed as a Colpitt circuit side in one attached to the mounting plate 19 Tube oscillator is mounted on a leaf spring 26 clamped to the oscillator frequency supporting bracket 25, Matching oscillation circle 2 with a circular In the support bracket 24 are between the clamping coil 3, the point of two condi-tions connected in series and the pressure point of the regulating element an announcer 4 and 4 'is bridged. One end of the 20 number of actuating anode circle standing in a direction transverse to the spring is arranged capacitively with the anode of the tube 1 screws 27, against which the spring is coupled; the one tapping point of the circular cone 16 when the control member 15 deflects to the right capacitor 4 'taken from feedback voltage sets in sequence. The ends of the set screws 27 is via a device 5, the effect of which dm. föl- lie on a curved line, and end through is described, the control grid of the tube 1 25-fold adjustment of the adjusting screws is he performed. The control grid of the tube 1 can also be achieved with the desired quadratic course of the curve, Via a leakage resistor 6 with the grounded cable which acts on the control element 15 spring method tied together. The anode of the tube 1 is over voltage (which, albeit to a small extent, also a choke 7 fed from a direct current source 9, is determined by the spring 26) according to the which is bridged by a smoothing capacitor 8. 30 represents the rash of the regulating body.

When the circuit oscillates, the movement of the control element 15 is

supply circuit 2 occurring circular current is limited for heating the directions by a stop 28, the

a workpiece 11 used, which is in a z. B. from with the left end of the control member 15 or one

a heating coil 10 formed load circuit on collar 30 cooperates on one at this is taken. The circle 2 is inductively attached to a pin 29 attached to the end of the control element.

Coupling coil 12 coupled, is brought to the output terminals.

13 the heating coil 10 is connected. The end of the pin 29 is on with a hinge In the circuit shown, the excitation of a lever 31 is attached, which is also articulated with Control grid is connected by means of an intermediate piece 32 in the feedback circuit, which is in a recorded device 5 stabilized. This one-40 fastened to the mounting plate 19 carrier 33 rotation consists of one in series with which Able. can be edited. The one made of conductive material resistance 6 between the control grid and cathode of the intermediate piece 32 is against the carrier 33 and the Tube 1 switched solenoid 14 with a movable lever 31 isolated. Both sides of the pivot point 34 are Baren control member 15 made of soft iron, the beder when energized with the intermediate part 32 made of conductive material Magnetic coil from the grid direct current against the 45 standing rods 35 and 36 articulated, the Action of a spring 16 is movable and by combining with various movable plates of the schema points the capacitors 17, 18 shown coupled to the control unit (see FIG. 1) Sators 17 and 18 changes the size of the feedback. are connected.

Now, according to the invention, the device is one with a view to a small control stroke designed in such a way that the used Federanoird- 5 ° favorable embodiment of the differential conformation has a force-displacement characteristic which is capacitors 17 and 18 in the form of capacitors lent completely coincides with that shown schematically in FIG. The differential cone the coil 14 and the regulating element, 15 existing capacitor consists of two sets of fixed and two Controller drive with approximately the maximum permissible sets of movable, parallel condensation excitation of the oscillator. Therefore, the 55 sator plates, with between every two of the same Regulating organ independent of its deflection and rate belonging to successive fixed plates for each load lying within the control range, load against each other in the opposite direction assume a position of equilibrium; this is bare plates are arranged.

but only stable if the grid direct current (and thus the two sets of immovably arranged plates the grid excitation) has the prescribed value. 60 are with 37, 37 ', 37 "or 38, 38', 38", the two Figures 2 and 2a show a side view or sets of movable plates of 40, 40 ', 40 "and 41, respectively. a plan view of a construction 41 ', 41 "which has been tried and tested in practice. The plates 37, 37', 37" are shown in FIG borrowed training of the schematically shown in Fig. 1 Fig. 1 (capacitor 18) with the tapping of the circle posed Device 5. This device contains capacitor 4 'connected to the feedback element Electromagnet with an on an assembly 65 voltage is removed. This is through the Plate 19 attached, completely closed yoke AC voltage generator 39 in Fig. 3 indicated. 20, in which a solenoid 14 is arranged. The immobile plates 38, 38 'and. 38 " The vertical legs of the yoke 20 are designated with the immovable plate of the 17 in FIG the axial direction of the magnet coil 14 and are grounded with the capacitor the openings 21 and 21 '. One connected to the screw 70 cathode of the oscillator tube 1.

The two sets of plates 40, 40 ', 40 "and 41, 41', 41 ″ are mechanically or electrically connected to the rotatable intermediate part 32 by rods 35 and 36, respectively. This intermediate part is electrically connected to the control grid of the tube 1.

In principle, the voltage divider 17, 18 can of course be more conventional as a differential reactance Design are trained, for. B. as a differential variable capacitor or as a differential inductance. It has has proven to be advantageous in practice to design the voltage divider in the feedback circuit to be capacitive, because when using inductors, especially at high operating frequencies (e.g. 1 MHz) unwanted phase rotations can occur in the feedback circuit, so that anode alternating voltage and current are not exactly in phase opposition, which is particularly the case when the generator is not fully loaded the anode loss becomes unfavorable and the tube draws more direct current power. Even can e.g. B. to regulate the feedback of the circular capacitor 4 (Fig. 1) designed as a variable capacitor (provided that the circuit detuning that occurs is harmless), the 15 is adjusted together with the spring 16, in which case the voltage divider 17, 18 is omitted, as in the following is shown with reference to FIG.

The mode of operation of the circuits described is explained in more detail with reference to the curves shown in FIG. The curve α represents the tensile force K _m exerted by the magnetic coil 14 on the control element 15 as a result of the (constant) grid traction current occurring with the maximum permissible excitation of the oscillator tube 1, corresponding to the deflection d of the control element. The distance d is indicated in FIG. 2 by the air gap between the core 22 and the end of the control element 15. The sensitivity of the electromagnet can be regulated by adjusting the core 22. In this curve, measured on a practical training course, the magnetic force is given in kg and the deflection d in mm for a grid direct current of 0.65 A. The construction of the springs 16 and 26 together with the setting of the adjusting screws 27 is chosen such that the curve which represents the spring tension K _v influencing the control element as a function of the deflection d of the control element runs as a square according to the characteristic curve shown in FIG , where the spring tension K _v in kg is plotted along the ordinate and the deflection of the control element is plotted below the axis of the same.

If, as shown in Fig. 2, by adjusting the adjusting screws 27, the spring tension curve ν is the mirror image of the curve α with respect to the d-axis, the control element will show such a deflection with every load that the differential capacitor coupled to the control element will cause the occurrence a grid direct current of 0.65 A.

In Fig. 5 is a simplified circuit of a device of the type shown in Fig. 1, which is shown by name at relatively low power, z. B. up to 10 kW can be used. Corresponding parts are provided with the same reference numerals in FIGS. 1 and 5.

The simplification consists essentially in the fact that the differential capacitor 17, 18 has been omitted and the magnitude of the feedback voltage that is applied to the end of the frequency-determining From circle 2 and fed to the control grid of the oscillator tube 1, by setting

development of one of the circuit capacitors, d. H. of the capacitor 4, is regulated; The setting of the capacitor 4 takes place by means of the cooperating with the spring 16 Control element 15 of the type described with reference to FIG. 1 and the curves according to FIG. 4 and way.

Claims (7)

PATENT CLAIMS: 1. High-frequency furnace with a grid-controlled electron tube os <ziil.ator, in which the Stabilizing the excitation of the control grid the size of the feedback automatically by means of a under spring tension control organ is regulated, the deflection of the field one of the Grid direct current excited magnet coil depends, characterized in that to achieve a astatic control is the curve which the magnetically exerted on the control organ Attraction due to the direct current of the grid with approximately the maximum permissible excitation of the oscillator corresponding to the deflection of the regulating organ, and the curve which the Represents the spring tension influencing the control element according to the deflection of the control element, are mirror images of each other with respect to the axis along which the deflection is plotted is, so that the regulating organ assume a position of equilibrium regardless of its deflection can. 2. High frequency furnace according to claim 1, characterized in that the spring is a square Has characteristic and consists of a leaf spring clamped on one side, the free End presses against the control element, and that between the pinch point and the contact point Adjusting screws are arranged on the regulating member along the spring, against which the spring is at Rashes of the regulating organ in sequence. 3. High-frequency furnace according to claim 2, characterized in that the control element for smooth Storage is supported by two leaf springs clamped on one side. 4. High frequency furnace according to claim 1 to 3, characterized in that the controller consists of a Solenoid with a completely closed yoke consists of two opposite legs has bores lying on the coil axis, as well as one with a non-magnetic one Pin equipped iron core, which is used as a control element in the remote from the spring arrangement Jochboihrung is slidably mounted and with a second, adjustably fastened in the other yoke bore and axially for receiving of the pin pierced iron core cooperates, the spring arrangement on the protruding End of the pin. 5. High frequency furnace according to claim 1 to 4, characterized in that the size of the f requenzbestknmenden The feedback voltage taken from the resonant circuit of the oscillator tube by changing a capacitor in the resonant circuit is regulated. 6. High frequency furnace according to claim 1 to 4, characterized in that for controlling the feedback a voltage divider designed as a differential reactance is used. 7. High frequency furnace according to claim 6, characterized in that a voltage divider Differential capacitor with two fixed and two parallel ones movable perpendicular to the plane of the plate Plate sets are used, with two from the control organ between two plates belonging to the same set moved in opposite directions and between these cherishes a record belonging to the other fixed set. Publications taken into consideration: Book by Leonhard, "The automatic regulation", Springer-Verlag, 1949, p. 31;
U.S. Patent No. 2,351,629. 1 sheet of drawings © 609 839/331 3.57