DEVICE FOR SUPPLYING A MOBILE MULTI-MELT DEVICE WITH HEATING POWER AND / OR FOR TEMPERATURE MEASUREMENT

Description

[0001] The invention relates to a device and a method for detecting a temperature and / or a heating power of a multi-melting device. State of the art

[0002] DE 10 2017 212 528 A1 discloses a hot-melt gluing device with a hot-melt glue stick. The hot-melt gluing device comprises a hot-melt glue stick and an external, electrical heating station. The heating station is designed to heat the hot-melt glue stick using an inductive heater.

[0003] US 2015 / 078799 A1 discloses an induction heated heating module for a hot melt applicator pen, comprising a temperature measuring circuit.

[0004] EP 0 190 452 A1 discloses a bridge circuit for temperature monitoring of a hot melt adhesive application system. Disclosure of the invention

[0005] The object of the invention is to provide an improved device for detecting a temperature and / or a heating power of a heating section of the multi-melting device.

[0006] Furthermore, the object of the invention is to provide an improved method for detecting a temperature and / or a heating power of a heating section of the multi-melting device.

[0007] The objects of the invention are solved by the independent patent claims.

[0008] Further developments of the device and the method are specified in the dependent claims.

[0009] A device for detecting a temperature and / or a heating power of a

[0010] A multi-melting device is proposed, wherein the device has an electrical circuit designed to detect the temperature of the multi-melting device. The electrical circuit is designed to be inductively connected to another electrical circuit of the multi-melting device. In addition, the electrical circuit has a measuring circuit designed to measure a current and / or a voltage of the electrical circuit. Furthermore, an evaluation circuit is provided which is designed to determine the temperature of the multi-melting device depending on the measured voltage and / or depending on the measured current.The electrical circuit is designed to inductively supply the multi-melting device with heating power, wherein the electrical circuit has a rectifier and an inverter, wherein the rectifier supplies the inverter with power via two bus lines, wherein the inverter is designed to generate an alternating voltage for supplying a transmitting coil, wherein the evaluation circuit detects the voltage between the bus lines in order to estimate a heating power transmitted to the multi-melting device and / or a temperature of the multi-melting device.

[0011] Because the electrical circuit is designed to provide heating power for the multi-melting device, a compact design of the electrical circuit with low circuit complexity is achieved.

[0012] In one embodiment, the evaluation circuit is designed to determine the inductively transmitted heating power and / or the temperature of the multi-melting device depending on a time profile and / or a minimum value of the measured voltage.

[0013] The fact that the electrical circuit can be inductively coupled to another electrical circuit enables a simple connection between the device and the multi-melting device.

[0014] In an example not according to the invention, the electrical circuit has electrical contacts, which can be used to establish a direct connection to other electrical contacts of the additional electrical circuit of the multi-melting device. This creates a technically simple connection.

[0015] In one embodiment, the electrical circuit has at least one measuring resistor for measuring the voltage and / or current, wherein the electrical circuit is configured to change at least one measuring resistor of the electrical circuit. Thus, the measuring range of the circuit can be changed.

[0016] In one embodiment, the evaluation circuit is designed to estimate the transmitted heating power and / or the temperature of the multi-melting device depending on a change in the voltage between the bus lines, in particular depending on a temporal profile of the voltage, in particular depending on a minimum voltage.

[0017] In one embodiment, the inverter comprises a first series circuit with two switches, wherein the first series circuit has a second output line between the two switches, wherein the first series circuit has a third output line after the second switch, wherein the second output line is connected to a first terminal of a coil, wherein the third output line is connected to a second terminal of the coil via a capacitor.

[0018] In one embodiment, the inverter has a first series circuit with two switches, wherein the first series circuit has a third output line upstream of the first switch, wherein the first series circuit has a second output line between the two switches, wherein the first series circuit has a third output line downstream of the second switch, wherein the second output line is connected to a first terminal of a transmitting coil, wherein the first and the third output lines are connected to a second terminal of the transmitting coil, wherein a supply circuit is formed between the first and the second output lines, wherein the supply circuit has a second series circuit, wherein the second series circuit has a first capacitor and a first diode, wherein the second series circuit is connected to the first and the second output lines,wherein a first supply line is connected between the capacitor and the first diode, wherein the first supply line is connected to a first terminal of a second diode, wherein a parallel circuit with a Zener diode and a second capacitor is provided, wherein the parallel circuit is connected with a first terminal to a second terminal of the second diode, wherein the parallel circuit is connected with a second terminal to the first output line, wherein an electrical resistor is connected between the second terminal of the second diode and the third output line, wherein a DC voltage is provided between the second terminal of the second diode and the first output line.

[0019] A multi-melting device with a further electrical circuit and an inductive heating element for heating a melting material is proposed, wherein the further electrical circuit has at least one measuring resistor which can be connected inductively or via the contacts to an electrical circuit of a device according to the invention for inductively supplying a mobile multi-melting device with heating power and / or for detecting a temperature of the multi-melting device.

[0020] A method for detecting a temperature and / or a heating power of a multi-melting device according to the invention is proposed, wherein an electrical circuit is brought into operative connection with another electrical circuit of the multi-melting device, wherein a current and / or a voltage of the electrical circuit is detected, and wherein a temperature of the multi-melting device is determined depending on the measured voltage and / or depending on the measured current.

[0021] The electrical circuit inductively supplies the multi-melting device with heating power, wherein the electrical circuit has a rectifier, wherein the rectifier supplies an inverter with power via two bus lines, wherein the inverter is designed to generate an alternating voltage for supplying an electrical coil, wherein the voltage between the bus lines is detected in order to estimate the temperature of the multi-melting device and / or the heating power transferred to the multi-melting device depending on the voltage.

[0022] In one version, a temperature of the multi-melting device is determined depending on a phase shift between current and voltage.

[0023] In one embodiment, a measuring resistor of the electrical circuit is changed to set a different measuring range.

[0024] Embodiments of the device and the method are explained in more detail with reference to figures.

[0025] They show: Fig. 1 a perspective, partially sectioned view of a device for supplying the mobile multi-melter with heating power and / or for detecting a temperature of a heating section of the multi-melter, Fig. 2 a schematic representation of a partial section of an electrical circuit of the device, Fig. 3 a schematic representation of a measured current curve and a measured voltage curve, Fig. 4 a schematic representation of a partial cross-section of an embodiment of the device and a partial cross-section of an embodiment of the multi-melting device, Fig. 5 a schematic representation of a partial section of an electrical circuit of the device, Fig. 6 an electrical equivalent circuit diagram of an electrical circuit of the device for inductive heating of the multi-melting device, Fig. 7 a measurement diagram in which the measured voltage over time with and without an inductively heated multi-melting device, Fig. 8 a schematic representation of an electrical equivalent circuit diagram of a further embodiment of the electrical circuit of the device with a direct current source, and Fig. 9 a schematic representation of a diagram for operating the embodiment of the Fig. 8 . Description of the embodiments

[0026] Fig. 1 shows a schematic representation of a multi-melting device 100 with a heating station 200. The heating station 200 has a holder 202 into which, for example, a cordless, mobile multi-melting device 110 is plugged. The multi-melting device 110 can, for example, be designed in the form of a hot-melt glue stick and be equipped with a material stick 112 or in the form of an adhesive cartridge. The material stick 112 can, for example, be formed with a conventional hot-melt adhesive that has a solid consistency at room temperature and, upon reaching a processing temperature, for example in a range of 160°C to 200°C, changes from the solid state into a viscous, pasty, adhesive state. After reaching the processing temperature, the hot-melt adhesive or hot-melt plastic preferably remains processable for a period of 5 to 90 seconds, even without further heat input.Depending on the selected embodiment, the multi-melting device 110 may also comprise other types of materials, in particular plastics in the form of a material stick, which can be converted from a solid to a viscous paste-like state using an elevated temperature.

[0027] In addition, depending on the selected embodiment, the multi-melting device 110 can be provided with a material pin, for example, made of different types of hot melt adhesives, special waxes, or the like, each with different colors, levels of translucency, melting temperatures, strengths, etc. Furthermore, the materials of the material pins can comprise different solid particles and / or filler particles, such as glitter particles, microcrystals, metal foil particles, etc.

[0028] The heating station 200 has a non-contact, electrical induction heater 210. The induction heater 210 is designed to heat the multi-melting device 110 at least in part without contact. Compared to conventional resistance heating elements, the induction heater 210 enables short heating phases, targeted heating, and good control dynamics with significantly increased efficiency. Furthermore, different heating zones can be easily created using inhomogeneous magnetic fields, for example, for preheating and melting the material pin. The induction heater 210 also enables a compact, pin-like design for the multi-melting device 110, while its pin housing can nevertheless be well thermally insulated or encapsulated, in particular to eliminate the risk of burns for the user.The multi-melting device 110 has an at least substantially rod-shaped pin housing 114 and a hollow-cylindrical feed section 116 for the material pin 112. A holding section 118 for the user to grip is axially adjacent to the feed section 116. The holding section 118 can be received in a receiving shaft 122 of the holder 202 of the heating station 200, creating a narrow annular gap 120. The material stick 112 can be advanced axially, for example, by being pushed in by the user. Alternatively, a mechanical feed device can be provided, which can be actuated by at least one of the user's fingers in the area of ​​the respective holding sections of the multi-melting device 110.

[0029] A control device 270, which includes a control unit and an electrical circuit, is integrated into the heating station 200. The control device 270 can be connected wirelessly or via a contact socket to an external computing unit, such as a PC, a computer tablet, or a smartphone. The heating station 200 can be powered via a power cable or independently of the mains via batteries.

[0030] The inductive heater 210 comprises, for example, a first heating coil 220 for melting the end of the material pin, as well as a second heating coil 222 for preheating the material pin 112. Instead of two electrically separated heating coils 220, 222, only one heating coil can be provided. Furthermore, each heating coil can have different winding densities in certain sections to generate an inhomogeneous magnetic field. The first heating coil 220 interacts with a metallic heating nozzle 224, which is arranged at a front end in the multi-melting device 110, by means of an alternating magnetic field. The heating nozzle 224 has a substantially hollow conical shape, with an end-side, nozzle-like outlet opening 226 provided in the region of a cone tip. The second heating coil 222 is coupled to a metallic, hollow-cylindrical preheating sleeve 228 by means of an alternating magnetic field.With the help of the two heating coils 220, 222, eddy currents are induced in the heating nozzle 224 and the preheating sleeve 226, respectively, which, due to the ohmic losses occurring therein, lead to a desired, defined temperature increase in the heating nozzle 224 and the preheating sleeve 226. To generate the necessary alternating magnetic fields, the heating coils 220, 222 are supplied with a current with a suitable temporal profile, in particular frequency, amplitude, and curve shape, by means of the electrical control device 270. Depending on the selected embodiment, the heating nozzle 224 and the preheating sleeve 226 can be formed from a ferromagnetic material such as iron, steel, etc. In this embodiment, the temperature increase in the heating nozzle and the preheating sleeve is heated by the occurrence of hysteresis losses.

[0031] The heated multi-melting device 110 can be removed from the holder 202, and a user can precisely dose the molten or liquefied material of the material pin 112, which exits through the outlet opening 226 in the area of ​​the heating nozzle 224, and guide it to a workpiece to be processed. Instead of the illustrated pin shape, the multi-melting device 110 can also be designed in the form of a hot-melt gun and have a corresponding handle and actuating elements.

[0032] In addition, instead of the described heating nozzle 224 and preheating sleeve 228, the multi-melting device 110 can also have differently shaped inductively heatable heating elements with which the material pin 112 can be heated and in particular liquefied.

[0033] In an example not according to the invention, the electrical circuit 290 of the control device 270 comprises a measuring circuit 300 which is Fig. 2 is shown schematically. The measuring circuit 300 has an AC voltage source 310, a series circuit with a first resistor 320 and a second resistor 330. In addition, a third electrical resistor 340 is provided parallel to the second electrical resistor 330. Furthermore, the measuring circuit 200 has a first electrical contact 350, which is connected to the connecting line from the AC voltage source to the first electrical resistor 320. Furthermore, a second electrical contact 360 is formed at the second terminal of the fourth electrical resistor. In addition, a voltmeter 370 is connected between the second electrical contact 360 and the connecting line from the first electrical resistor 320 and the second electrical resistor 330.

[0034] In addition, schematically in Fig. 2 a further electrical circuit 380 is shown, which is arranged in the multi-melting device 110. For this purpose, the multi-melting device 110 has further first and second electrical contacts 390, 400. The further electrical circuit 380 has a temperature-dependent measuring resistor 410 and an electrical coil 415. In the illustrated embodiment, the further first electrical contact 390 is in direct contact with the first electrical contact 350. The further second electrical Kontakt 400 is in direct contact with the second electrical contact 360, as shown schematically in Fig. 4 is shown.

[0035] For optimal operation of the multi-melting device 110, it is advantageous to determine the temperature in the multi-melting device 110. The temperature can be determined by a voltage measurement using the voltmeter 370 with the aid of the measuring circuit 300 and the temperature-sensitive measuring resistor 410. A measuring bridge is used, wherein part of the measuring bridge consists of the measuring resistor 410 of the multi-melting device 110. The measuring resistor 410 is designed such that its ohmic resistance depends, for example, linearly on the temperature. Depending on the selected embodiment, the ohmic resistance of the measuring resistor 410 can also have a non-linear dependency, which can be stored, for example, as a characteristic map in a data memory of a control unit 420. The measuring resistor 410 is preferably arranged in the region of the heating nozzle 224 in the multi-melting device.

[0036] In addition, the control unit 420 is provided, which, for example, controls the AC voltage source 310 to provide a desired voltage and / or current. Furthermore, the control unit 420 is connected to the voltmeter 370. Furthermore, a current measuring device 430 is provided in the series circuit of the first and second resistors, which is also connected to the control unit 420.

[0037] The control unit 420 uses the AC voltage source 310 to specify a predetermined voltage waveform, for example, in the form of a sinusoidal voltage waveform. At the same time, the voltage is measured using the voltmeter 370, and the current is measured using the current measuring device 430. Depending on the temperature of the multi-melting device 110, different voltages are measured by the voltmeter. Furthermore, the resistance of the measuring resistor 410 influences a phase shift Φ between the measured voltage and the measured current. The control unit 420 has the data memory in which the corresponding temperatures of the multi-melting device 110 are stored for the measured voltages or the measured phase shift between current and voltage.

[0038] Fig. 3 shows a schematic diagram of the course of the measured voltage U and the course of the measured current I over a phase angle which is plotted along the X-axis.

[0039] Fig. 4 shows in a schematic representation a partial section of a non-inventive example of the arrangement of the Fig. 1 and 2with a multi-melting device 100 for supplying the mobile multi-melting device 110 with heating power and / or for detecting a temperature of a heating section of the multi-melting device and the multi-melting device. In this embodiment, the first electrical contact 350 is spring-loaded toward the multi-melting device 110 by means of a first mechanical spring 440. Furthermore, the second electrical contact 360 is also spring-loaded toward the multi-melting device 110 by means of a second mechanical spring 450. The multi-melting device 110 has the further first electrical contact 390, which bears directly against the first electrical contact 350. Furthermore, the multi-melting device 110 has the further second electrical contact 400, which bears against the second electrical contact 360.The spring loading of the electrical contacts achieves improved electrical contact between the heating station 200 and the multi-melting device 110.

[0040] Fig. 5 shows a schematic representation of a further embodiment of a measuring circuit 300, which is similar to the measuring circuit 300 of Fig. 2 In this embodiment, however, a series circuit of a third electrical resistor 510, a fourth electrical resistor 520, and a transmitting coil 530 are arranged parallel to the first and second electrical resistors 320, 330. The voltmeter 370 is connected between the connecting lines between the first electrical resistor and the second electrical resistor 320, 330 and between the connecting line between the third electrical resistor and the fourth electrical resistor 510, 520. In this embodiment, an inductive coupling is achieved between the measuring circuit 300 and the measuring resistor 410 of the multi-melting device 110. For this purpose, the multi-melting device 110 has a series circuit comprising the measuring resistor 410, a measuring coil 415, and a measuring capacitor 418, which form a resonant circuit. The inductive coupling is achieved via the transmitting coil 530 and the measuring coil 415.

[0041] The current measuring device 430 is arranged between the AC voltage source 310 and the parallel connection of the two series circuits. The voltage in the measuring path of the measuring circuit is achieved by the inductive coupling between the two coils 530, 415. In this embodiment, the voltage is also influenced depending on the temperature of the measuring resistor 410. The control unit 420 is connected to the AC voltage source 310, to the current measuring device 430, and to the voltmeter 370. Furthermore, the control unit 420 has a data memory in which reference values ​​for the temperature values ​​of the multi-melting device for the measured voltages, currents, and / or phase shifts between the measured voltages and currents are stored.Thus, the control unit 420 can use the stored reference values ​​to estimate the temperature of the multi-melter based on the measured voltages, currents and / or phase shifts between the voltages and currents.

[0042] In addition, the inductive coupling with the additional measuring circuit of the multi-melting device 110 results in a phase shift between the voltage and current in the heating station's measuring circuit, depending on the temperature of the measuring resistor 410. This arrangement allows the temperature of the multi-melting device 110 to be measured contactlessly.

[0043] Depending on the selected embodiment, the measuring circuit 300 can have a switch 540 that can connect three third electrical resistors 510, 511, 512 of different sizes to the second series circuit. The switch 540 can be switched by the control unit 420 or directly by an operator. The switch 540 can be designed as a rotary control 540. Thus, the operating range of the measuring circuit can be adjusted in steps. This allows different materials to be processed. The step-by-step adjustment can optionally also be performed continuously using a rotary control.

[0044] The inductive coupling also enables evaluation based on the shift in the system's resonant frequency. The system's resonant frequency shifts with temperature. The resonant frequency is measured. Furthermore, the control unit 420 has a data memory in which temperatures of the multi-melter are stored at resonant frequencies. Thus, the temperature of the multi-melter can be determined based on the resonant frequency. For example, the evaluation can be detected via a Bode diagram based on a change in sign from plus to minus in the slope of the amplitude spectrum.

[0045] Fig. 6 shows a schematic representation of an electrical equivalent circuit diagram for an electrical circuit 290 of an inductive heater of the heating station 200. From a second alternating voltage source 600, an alternating voltage v ac with a current i ac is fed via an EMC filter 610 to a parallel circuit of a first series circuit 620 with a first and a second diode 630, 640 and a second series circuit 650 with a third and a fourth diode 660, 670. The first and the second series circuit 620, 650 are connected to a first bus line 680 and a second bus line 690. The first and the second series circuit 620, 650 represent a bridge rectifier which transfers the alternating voltage of the alternating voltage source 600 into positive voltages on the first bus line 680. A first capacitor 700 is connected between the first and the second bus line 680, 690.Current ib flows on the first bus line 680, and voltage vb is present at the first capacitor 700. Current and voltage measuring devices are also provided to measure the current ib of the first bus line 680 and the voltage vb present at the first capacitor 700. The current and voltage measuring devices are not shown.

[0046] The first bus line 680 and the second bus line 690 are connected via a series circuit comprising a first switch 710 and a second switch 720. The first and second switches 710, 720 are switched by the control unit 420. The first and second switches 710, 720 are designed, for example, as field-effect transistors. The first and second switches 710, 720 are connected to one another via a connecting line 730. The connecting line 730 is connected via a first output line 780 to a second transmitting coil 740, which is schematically represented in the form of an ohmic resistor 750 and an inductive resistor 760. The current io flows on the first output line 780. A second terminal of the transmitting coil 740 is connected to the second bus line 790 via a further capacitor 770. A voltage vc is present across the further capacitor 770.The series circuit with the first and second switches 710, 720 provides an alternating voltage vo via the output line 780 and the second output line 790.

[0047] For high voltages between the first and second bus lines 780, 790, it is advantageous to select the first capacitor 700 with a low capacitance. However, in these systems, it is advantageous to determine the presence of an inductive load on the transmit coil 740 and to estimate the inductive heating power delivered by the transmit coil 740.

[0048] In Fig. 6 The current and voltage curves are shown schematically, where v ac is the voltage at the output of the alternating voltage source 600, i ac is the current at the output of the alternating voltage source 600, vb is the voltage at the first capacitor 700, ib is the current flow via the first bus line 680, io is the current flow via the first output line 780, vc is the voltage at the second capacitor 750 and vo is the voltage between the first and second output lines 780, 790.

[0049] The control unit 420 is designed to detect the bus voltage vb at the first capacitor 700 using the voltmeter (not shown). Depending on the measured bus voltage, the presence of an inductive load can be detected. In addition, the measured bus voltage can be used to estimate the heating power transmitted using the transmitting coil. Thus, based on the bus voltage and the duration during which heating power is transmitted inductively to the multi-melting device, the temperature of the multi-melting device can be estimated. For this purpose, corresponding experimentally determined values ​​are stored in a data memory of the control unit 420, which represent the presence of an inductive load, i.e., a multi-melting device, depending on a minimum bus voltage. In addition, values ​​for the transmitted inductive heating power are stored in the data memory as a function of the minimum bus voltage and the measured current on the first bus line.In addition, values ​​for the temperature of the multi-melting device are stored in the data memory depending on the minimum bus line and / or the current on the first bus line and / or the duration of the current supply to the transmitting coil.

[0050] Tests have shown that the bus voltage vb varies depending on the presence of an inductive load or depending on the transmitted transmission power of the transmitting coil 740, and thus depending on the transmitted heating power. The control unit 420 has a data memory in which reference values ​​for the bus voltages, the transmitted heating power, and the temperature of the multi-melting device are stored. Thus, the control unit 420 can estimate and determine the temperature of the multi-melting device based on the bus voltage and / or the current of the first bus line and / or the duration of the current supply to the transmitting coil 740.

[0051] Fig. 7 shows a schematic diagram for several measured bus voltages. The diagram plots the amplitude A of the bus voltage in volts over time. The measured bus voltage vb is shown as a dashed line and is designated U1 for the case where no inductive load, i.e., no multi-melting device 110, is provided near the heating station 200 to receive inductive heating power. It can be seen that the bus voltage repeatedly reaches the value of 0 V.

[0052] If, however, an inductive load is present, i.e., a multi-melting device 110 is arranged at the heating station 200, the bus voltage vb designated U2 does not drop to 0 V, but oscillates between values ​​of, for example, more than 100 V and the maximum voltage of 360 V, as shown by the second characteristic curve U2, which is shown as a solid line. Thus, in this case, 100 volts represents a minimum bus voltage Um, as shown in Fig. 7 The control unit 420 has a data memory in which reference values ​​for the transmitted heating power and the temperature of the multi-melter are stored for minimum bus voltages. Thus, the control unit 420 can estimate and determine the temperature of the multi-melter based on the bus voltage and / or the current of the first bus line and / or the duration of the energization of the transmitting coil 740.

[0053] In addition, a threshold value S of, for example, 100 V can be set. If the bus voltage does not fall below the threshold, the control unit 420 detects the presence of an inductive load or the presence of a multi-melt device in the vicinity of the transmitting coil. The bus voltage can be measured, for example, using an analog comparator or an HD converter. Furthermore, comparison curves or threshold values ​​for the measured bus voltage can be stored in the data memory of the control unit 420. Based on previously conducted tests, the heating power and / or temperature of the multi-melt device transmitted to the multi-melt device 110 are assigned to these threshold values. For example, the higher the maximum threshold below which the bus voltage does not fall, the greater the transmitted heating power.

[0054] In this way, the control unit 420 can estimate the transmitted heating power and thus the temperature prevailing in the multi-melting device 110 based on the measured bus voltage vb. The estimated value of the temperature of the multi-melting device 110 can be used to adjust the emitted inductive heating power such that the multi-melting device 110 has a predetermined temperature in the area of ​​the heating nozzle. For this purpose, corresponding experimentally determined values ​​are stored in the data memory of the control unit 420.

[0055] Fig. 8 shows a further embodiment of an electrical circuit 290 of the heating station 200. The electrical circuit essentially corresponds to the circuit of the Fig. 6 , however, a supply circuit 950 for a DC voltage is additionally provided. For this purpose, the circuit has a third output line 800, which is routed from the first bus line 680 via a third capacitor 810 to the second terminal of the transmitting coil 740.

[0056] Furthermore, a further series circuit 820 consisting of a third capacitor 830 and a fifth diode 840 is provided, wherein the fifth diode 840 and the fourth capacitor 830 are connected between the first and second output lines 780, 790. Furthermore, an additional series circuit 850 is provided, which has a seventh resistor 860 and a Zener diode 870. The additional series circuit 850 is arranged between the third output line 800 and the first output line 790. The connecting line between the fourth capacitor 830 and the fifth diode 840 is connected via a sixth diode 880 to the connecting line between the seventh resistor 860 and the Zener diode 870. Furthermore, a fifth capacitor 890 is connected between the connecting line between the seventh resistor 860 and the Zener diode 870 and the second output line 790.A DC voltage is provided at the fifth capacitor 890, for example, for operating parts of the electrical circuit, in particular for operating the control unit 420. The DC voltage can be in the range of, for example, 6 to 20 V and is set by the Zener diode 870. The fifth and sixth diodes 840, 880 are designed as fast diodes. The fourth capacitor 830 reduces the voltage change over time and the switching losses. The desired level of the DC voltage is set by the selection of the Zener diode 870. The fifth capacitor 890 stores the DC voltage provided by the Zener diode 870. Whenever the inverter in the form of the first and second switches 710, 720 is activated, the desired DC voltage is provided at the output of the fifth capacitor 890. The seventh resistor 860 provides a wake-up circuit for the electrical supply of the circuit.This ensures that the required voltage is provided before the inverter is activated. This is achieved by reverse-biasing the Zener diode.

[0057] Fig. 9 shows a diagram showing the temporal behavior of the voltage curves of the circuit of the Fig. 8 During a start-up phase 900, the AC voltage source 600 generates an AC voltage at a time T0. This provides a supply voltage Vs of, for example, 12 V to the fifth capacitor 890. Only after a predetermined start-up phase 900 has elapsed, at time T1, do the switches 710, 720 begin to switch during a normal operating phase 910. List of reference symbols

[0058] 100 Multi-melting device 110 Multi-melting unit 112 Material pin 114 Pin housing 116 Feed section 118 Holding section 120 Annular gap 122 Receiving shaft 200 Heating station 202 Holder 210 Induction heater 220 First heating coil 222 Second heating coil 224 Heating nozzle 226 Outlet opening 228 Preheating sleeve 270 Control device 290 Electrical circuit 300 Measuring circuit 310 Alternating voltage source 320 First electrical resistor 330 Second electrical resistor 340 Third electrical resistor 350 First electrical contact 360 Second electrical contact 370 Voltmeter 380 Further electrical circuit 390 Further first electrical contact 400 Further second electrical contact 410 Measuring resistor 415 Measuring coil 420 Control unit 430Current measuring device 440First spring 450Second spring 510Third electrical resistor 511Further third electrical resistor 512Further third electrical resistor 520Fourth electrical resistor 530Transmitting coil 540Rotary control 600SecondAC voltage source 610 EMC filter 620 First series circuit 630 First diode 640 Second diode 650 Second series circuit 660 Third diode 670 Fourth diode 680 First bus line 690 Second bus line 700 First capacitor 710 First switch 720 Second switch 730 Connecting line 740 Second transmitting coil 750 Ohmic resistor 760 Inductive resistor 770 Second capacitor 780 First output line 790 Second output line 800 Third output line 810 Third capacitor 820 Further series circuit 830 Fourth capacitor 840 Fifth diode 850 Additional series circuit 860 Seventh resistor 870 Zener diode 880 Sixth diode 890 Fifth capacitor 900 Start phase 910Operating phase 950Supply circuit

Claims

1. Apparatus for measuring a temperature and / or a heating power of a multi-purpose melting device (110), having an electrical circuit (290) which is designed to measure the temperature of the multi-purpose melting device (110), wherein the electrical circuit (290) is designed to be inductively connected to a further electrical circuit (380) of the multi-purpose melting device (110), having a measuring circuit (300) which is designed to measure a current and / or a voltage of the electrical circuit (290), and having an evaluation circuit (420) which is designed to determine the temperature of the multi-purpose melting device (110) on the basis of the measured voltage and / or on the basis of the measured current, wherein the electrical circuit (290) is designed to inductively supply heating power to the multi-purpose melting device (110), characterized in that the electrical circuit (290) has a rectifier (630, 640, 660, 670) and an inverter (710, 720), wherein the rectifier (630, 640, 660, 670) supplies power to the inverter (710, 720) via two bus lines (680, 690), wherein the inverter (710, 720) is designed to produce an AC voltage for supplying power to a transmitter coil (740), wherein the evaluation circuit (420) measures the voltage between the bus lines (680, 690) in order to estimate a heating power transmitted to the multi-purpose melting device (110) and / or a temperature of the multi-purpose melting device (110).

2. Apparatus according to Claim 1, characterized in that the evaluation circuit (420) is designed to determine the inductively transmitted heating power and / or the temperature of the multi-purpose melting device (110) on the basis of a time characteristic and / or of a minimum value of the measured voltage.

3. Apparatus according to either of the preceding claims, wherein the electrical circuit (290) has at least one measuring resistor (510) for measuring the voltage and / or the current, wherein the electrical circuit is designed to alter the at least one measuring resistor (510, 511, 512) of the electrical circuit.

4. Apparatus according to Claim 1, wherein the evaluation circuit (420) is designed to estimate the transmitted heating power and / or the temperature of the multi-purpose melting device (110) on the basis of a change in the voltage between the bus lines (680, 690), in particular on the basis of a time characteristic of the voltage, in particular on the basis of a minimum voltage.

5. Apparatus according to one of Claims 1 to 3, wherein the inverter (710, 720) has a first series circuit comprising two switches, wherein the first series circuit has a second output line (780) between the two switches, wherein the first series circuit has a third output line (790) downstream of the second switch, wherein the second output line is connected to a first terminal of a transmitter coil (740), wherein the third output line is connected to a second terminal of the transmitter coil (740) via a capacitor (770).

6. Apparatus according to one of Claims 1 to 3, wherein the inverter (710, 720) has a first series circuit comprising two switches (710, 720), wherein the first series circuit has a third output line (800) upstream of the first switch (710), wherein the first series circuit has a second output line (780) between the two switches, wherein the first series circuit has a first output line (780) downstream of the second switch (720), wherein the second output line (780) is connected to a first terminal of a transmitter coil (740), wherein the first and third output lines (800, 790) are connected to a second terminal of the transmitter coil (740), wherein a power-supply circuit (950) is formed between the first and the second output line, wherein the power-supply circuit (950) has a second series circuit, wherein the second series circuit has a first capacitor (830) and a first diode (840), wherein the second series circuit is connected to the first and second output lines (790, 780), wherein a first power-supply line is connected between the capacitor (830) and the first diode (840), wherein the first power-supply line is connected to a first terminal of a second diode (880), wherein a parallel circuit comprising a Zener diode (870) and a second capacitor (890) is provided, wherein a first terminal of the parallel circuit is connected to a second terminal of the second diode, wherein a second terminal of the parallel circuit is connected to the first output line (790), wherein an electrical resistor (860) is connected between the second terminal of the second diode and the third output line, wherein a DC voltage is provided between the second terminal of the second diode and the first output line (790).

7. Multi-purpose melting device (110) according to one of the preceding claims, having a further electrical circuit (380) and an inductive heating element (224) for heating a melting material, wherein the further electrical circuit (380) has at least one measuring resistor (410) which is able to be inductively connected to an electrical circuit (290) of an apparatus for inductively supplying heating power to a mobile multi-purpose melting device and / or for measuring a temperature of the multi-purpose melting device.

8. Method for measuring a temperature of a multi-purpose melting device according to one of the preceding claims, wherein an electrical circuit is brought into operative connection with a further electrical circuit of the multi-purpose melting device, wherein a current and / or a voltage of the electrical circuit is measured, and wherein a temperature of the multi-purpose melting device is determined on the basis of the measured voltage and / or of the measured current, wherein the electrical circuit inductively supplies heating power to the multi-purpose melting device, characterized in that the electrical circuit has a rectifier, wherein the rectifier supplies power to an inverter via two bus lines, wherein the inverter is designed to produce an AC voltage for supplying power to an electric coil, wherein the voltage between the bus lines is measured in order to estimate the temperature of the multi-purpose melting device and / or the heating power transmitted to the multi-purpose melting device, on the basis of the voltage.

9. Method according to Claim 8, wherein a temperature of the multi-purpose melting device is determined on the basis of a phase shift between current and voltage.

10. Method according to either of Claims 8 and 9, wherein a measuring resistor of the electrical circuit is altered to set a different measuring range.