EP4264649A1

EP4264649A1 - Electronic switching device for demagnetizing ferromagnetic material

Info

Publication number: EP4264649A1
Application number: EP21834781.3A
Authority: EP
Inventors: Albert Maurer
Original assignee: Maurer Magnetic AG
Current assignee: Maurer Magnetic AG
Priority date: 2020-12-17
Filing date: 2021-12-08
Publication date: 2023-10-25
Also published as: US20230420171A1; CN116648763A; CH718185A1; WO2022128685A1

Abstract

The invention relates to an electronic circuit (10) for demagnetizing ferromagnetic material using a resonance oscillation having a prolonged decay time. The circuit comprises a voltage source (20) and a conductor loop (30) connected thereto, in which conductor loop a demagnetizing resonant circuit (40) is arranged for forming a decaying, alternating magnetic field. In addition, in the conductor loop (30), a resonant circuit battery switch (31) is arranged in series with the demagnetizing resonant circuit (40), and a recharge resonant circuit (50) for pulsed recharging of a charging current into the demagnetizing resonant circuit (40) is arranged in parallel with the demagnetizing resonant circuit (40) and with the resonant circuit battery switch (31). In addition, a recharge store (60) which is arranged in parallel with the voltage source (20), with the recharge resonant circuit (50) and with the demagnetizing resonant circuit (40), as well as a recharge switch (32) for interrupting a charging current from the recharge store (60) are located in the conductor loop (30). A battery switch (33) for interrupting the voltage source (20) is also provided. The circuit (10) can be operated by a controller (70) for controlling the voltage source (20) and all switches (31, 32, 33, 43, 53). The invention also relates to a method for operating such a circuit.

Description

ELECTRONIC SWITCHING DEVICE FOR DEMAGNETIZING FERROMAGNETIC MATERIAL

technical field

The invention relates to an electronic switching device for demagnetizing ferromagnetic material by means of resonance oscillation with a prolonged decay time. This includes a voltage source and a conductor loop connected to it, in which a demagnetizing oscillating circuit is arranged to form a decaying, alternating magnetic field in which ferromagnetic material can be demagnetized during a decay time. The switching device is operable with a controller for controlling the voltage source and all switches.

State of the art

Various devices are known for demagnetizing ferromagnetic bodies. As a rule, alternating magnetic fields with a degressive amplitude are used. These magnetic fields are generated with conductor coils, also called demagnetizing coils, through which an electric current flows according to the desired strength of the magnetic field. The degaussing coil and the body to be degaussed are generally in a mutually fixed position relative to one another during the degaussing process.

In order to ensure the complete penetration of the magnetic field of alternating polarity into the body to be demagnetized during this process in the shortest possible time and with the lowest possible energy consumption, the aim is to generate a sinusoidal current curve. The easiest way to achieve this is with an electric oscillating circuit working in resonance, as described at the outset.

The advantages of this circuit are the particularly simple structure, the reliable maintenance of a degressive amplitude for the demagnetizing current and the almost loss-free conversion of the energy fed into the demagnetizing process. Such demagnetization circuits, which are based on the free decay of an oscillating circuit, are described in US Pat. No. 4,599,673 and in EP 0021274, for example.

A crucial disadvantage of such degaussing circuits is that the amplitude for the degaussing current decreases too quickly, resulting in a lack of effectiveness of this circuit in the degaussing process. This degradation, which is defined by the decrement in current and voltage in the oscillating circuit, is specified in the design of the degaussing coil for physical and material reasons. It consists of the losses given by the copper resistance of the Degaussing coil, defined by its dimensions and structure as well as by the hysteresis and eddy current losses in the body to be degaussed.

EP 0597181 also deals with a method for demagnetizing magnetic materials in a decaying alternating magnetic field. A parallel resonant circuit comprising two coils and a capacitor, into which energy is fed synchronously to the magnetic interaction in order to lengthen the decay time. In order to achieve this, a complex circuit with a sine-wave converter, a square-wave generator and a monoflop is proposed in order to introduce energy clocked from a recharging capacitor into the capacitor of the parallel resonant circuit.

Presentation of the invention

It is now the object of the present invention to describe a device based on the electronic switching device mentioned at the beginning, which has a longer decay time, but also shows a practicable solution that can be implemented with a small number of circuit components and a comparatively simply constructed control .

In addition, it is desirable that the switching device according to the invention can be operated with a single power source and/or that it can do without components that include integrated circuits (IC).

The tasks are solved by an electronic switching device with the features of the first patent claim. According to the invention, a switching device described in the introduction also comprises

- an oscillating circuit charging switch in the conductor loop, in series with the degaussing oscillating circuit,

- a recharging resonant circuit in the conductor loop, arranged parallel to the demagnetizing resonant circuit and to the resonant circuit charging switch, for pulsed recharging of a charging current into the demagnetizing resonant circuit when the resonant circuit charging switch is closed,

- an afterloading memory, which is arranged parallel to the voltage source, to the afterloading oscillating circuit and to the demagnetizing oscillating circuit, to supply energy to the afterloading oscillating circuit during the decay time,

- a recharging switch in the conductor loop for interrupting a charging current from the voltage source and from the recharging memory to the recharging oscillating circuit and to the demagnetizing oscillating circuit, - A charging switch for interrupting the charge source to the recharging memory, to the recharging oscillating circuit and to the demagnetizing oscillating circuit, with recharging pulses being able to be brought from the recharging oscillating circuit into the demagnetizing oscillating circuit during operation by means of a controller by opening and closing the switches, for extension the cooldown time until the energy from the reload storage is used up.

With such a switching device, the demagnetizing oscillating circuit, the resonant circuit and the reloading memory can be charged at the beginning of the process by the voltage source, which is then decoupled by a switch. The resonant oscillation of the demagnetizing oscillating circuit is then set in motion and periodically, preferably after the zero crossing of the oscillating circuit voltage, one or more recharging pulses from the recharging oscillating circuit are introduced into the resonant oscillation. Finally, the afterloading resonant circuit is loaded again by the afterloading memory so that it is ready to deliver the next pulse. This is repeated until the reload memory is exhausted. Thanks to these surges of energy, the decay time of the resonance vibration increases.

With this device it is possible to manage with only one voltage source. It is important here that a second oscillating circuit is used as the recharging oscillating circuit. In this, which only performs one half-oscillation at a time, the charge can be swapped with a polarity switch so that it can emit reloading impulses in the positive and negative direction, although it is always charged the same way by the reloading store. Alternatively, a polarity reversing switch could also be arranged between the recharging memory and the resonant resonant circuit, which always charges the resonant resonant circuit in alternating directions.

No integrated circuits (IC) are used, which reduces the susceptibility to failure and increases the service life and thus the reliability of this circuit.

Further embodiments according to the invention are described in the dependent claims.

Brief description of the drawings

The invention is explained in more detail below with reference to the drawings. Show it

1 shows a schematic representation of an electronic circuit for generating a decaying resonant oscillation;

Fig. 2 is a representation of a decaying resonance vibration according to FIG. 1 in time

Course;

FIG. 3 shows a section of the oscillation from FIG. 2 under the influence of recharging pulses; Fig. 4 is a schematic representation of an inventive electronic circuit for

generating a prolonged decaying resonance mode;

5 shows the circuit according to claim 4 in a preferred embodiment.

Ways to carry out the invention

1 shows a schematic representation of an electronic circuit 10 according to the invention for demagnetizing ferromagnetic material.

The circuit 10 comprises a degaussing coil 41 and an oscillating circuit capacitor 42 which are connected via an oscillating circuit switch 43 to form a degaussing oscillating circuit 40 . At the beginning of the process, the resonant circuit switch 43 is open. The demagnetizing oscillating circuit 40 is connected via a conductor loop 30 to a power source 20 which can charge the oscillating circuit capacitor 42 . The charging process can be interrupted via an oscillating circuit charging switch 31 .

When this charging process with the oscillating circuit voltage A is completed, the oscillating circuit charging switch 31 is opened and the charging current is thus interrupted. After the oscillating circuit switch 43 is closed, a resonant oscillation is set in motion: the oscillating circuit capacitor 42 discharges via the degaussing coil 41. The current in the oscillating circuit corresponds to an oscillation with an exponentially decaying amplitude that runs out freely in the natural frequency. 2 shows the resonant oscillation in this demagnetizing oscillating circuit 40 in the form of the curves of oscillating circuit voltage A and demagnetizing current B over time t. After the amplitudes of the oscillating circuit voltage A and demagnetizing current B have decayed, the oscillating circuit switch 43 is opened again and the circuit 10 is available for a next demagnetizing cycle, which begins again when the oscillating circuit charging switch 31 is closed.

FIG. 3 shows a section of the decay process from FIG. 2 with an oscillating circuit voltage A and a demagnetizing current B, with recharging pulses C being introduced at regular time intervals with a recharging current shown above. The latter are bipolar current pulses that are fed in at the instant immediately after the zero crossing D of the resonant circuit voltage A. Due to the additional energy fed in, the decay is delayed, so the amplitudes of the resonant circuit voltage A and the demagnetizing current B drop more slowly. This principle is known, but it has been shown that the implementation of it is complicated in terms of circuitry.

Embodiments according to the invention are shown in general form in FIG. 4 and in a preferred version in FIG. In Fig. 5, the components 40, 50 and 60 are shown as examples in electronic parts. Optionally, only some of them can be configured in this form. 4 shows an electronic circuit 10 for degaussing ferromagnetic material by a resonance oscillation with a prolonged decay time. It comprises a voltage source 20 and a conductor loop 30 connected to it, in which a demagnetizing oscillating circuit 40 is connected to form a decaying, alternating magnetic field in which ferromagnetic material can be demagnetized during a decay time t. This demagnetizing oscillating circuit 40 can be constructed as described in FIG. This was shown in FIG. 5 as an example. However, other arrangements of demagnetizing oscillating circuits 40 are also known. Together with the oscillating circuit charging switch 31, which is arranged in series with the demagnetizing oscillating circuit 40 in the conductor loop 30, the demagnetizing method described in FIG. 1 can be carried out.

The electronic circuit 10 also includes a recharging oscillating circuit 50 in the conductor loop 30 which is arranged in parallel with the demagnetizing oscillating circuit 40 and the oscillating circuit charging switch 31 . It is used for the pulsed recharging of a charging current in the demagnetizing oscillating circuit 40 when the oscillating circuit charging switch 31 is closed for a short time. As described above for Fig. 1, energy stored in the recharging oscillating circuit 50 can be charged at regular time intervals as short recharging pulses C in the degaussing oscillating circuit 40 can be initiated. The term "short" refers to the much shorter time period t compared to a total period of resonant oscillation in the degaussing tank circuit 40 as illustrated in FIGS.

Preferably, the natural frequency of recharging oscillating circuit 50 is at least 10, preferably at least 100 times greater than the natural frequency of demagnetizing oscillating circuit 40.

Furthermore, the conductor loop 30 of the electronic circuit 10 includes a recharging memory 60 which is arranged in parallel with the voltage source 20, the recharging oscillating circuit 50 and the demagnetizing oscillating circuit 40. It is intended to supply energy to the resonant circuit 50 during the decay time t. In addition, a recharging switch 32 is arranged in the conductor loop 30 which, when it is open, interrupts the charging current from the voltage source 20 and from the recharging memory 60 to the recharging oscillating circuit 50 and to the demagnetizing oscillating circuit 40 .

Finally, the electronic circuit 10 in the conductor loop 30 includes a charging switch 33 which interrupts the connection from the charge source 20 to the recharging memory 60, the recharging oscillating circuit 50 and the demagnetizing oscillating circuit 40 when it is opened. Accordingly, the charging switch 33 decouples the charge source 20 from the rest of the electronic circuit 10.

During operation, a controller 70 controls all switches 31, 32, 33, 43, 53 and, by opening and closing the switches 31, 32, 53, can introduce recharging pulses C from the recharging oscillating circuit 50 into the demagnetizing oscillating circuit 40 in order to extend the decay time. until the energy from the reloading memory 60 is used up. A rectifier diode 34 is preferably arranged in the conductor loop 30 in series with the voltage source 20 and the charging switch 33 in such a way that during use they prevent feedback from the recharging memory 60, from the recharging oscillating circuit 50 and from the demagnetizing oscillating circuit 40 into the voltage source 20 can.

When the switches, charging switch 33, recharging switch 32 and oscillating circuit charging switch 31 are closed, the demagnetizing oscillating circuit 40, the recharging oscillating circuit 50 and the recharging memory 60 are charged. Then said switches 33, 32 and 31 are opened again.

In this state, the degaussing process can begin. No further energy is introduced from the voltage source 20 until the end of this process. The charging switch 33 remains open during this time, the voltage source 20 therefore remains decoupled from the rest of the circuit 10.

At this point in time, the reloading memory 60 contains all of the energy that can be reloaded until the resonance oscillation of the demagnetizing oscillating circuit 40 has decayed. It includes, for example, a storage capacitor 62, as shown in FIG. In this way it can be achieved that only a single voltage source 20 is needed. The capacitance of the storage capacitor 62 is preferably at least twice as large, preferably at least three times as large as that of the resonant circuit capacitor 42.

All switches 31, 32, 33 are controlled by controller 70, which preferably also controls voltage source 20. In addition, further switches can be controlled by this controller 70 . The controller 70 may be separate from the circuit 10 or part of it.

As already described in relation to FIG. 3, the oscillating circuit charging switch 31 is briefly opened after the resonant oscillation in the demagnetizing oscillating circuit 40 has begun and the oscillating circuit voltage A has passed through the zero point D. The recharging oscillating circuit 50 now delivers its recharging pulse C to the demagnetizing oscillating circuit 40 . The resonant circuit charging switch 31 is closed again.

The recharging resonant circuit 50 is now charged by opening the recharging switch 32 by a current flowing from the recharging memory 60 . When the recharge resonant circuit 50 is recharged, the recharge switch 32 is closed again. After the next zero crossing of the oscillating circuit voltage A in the demagnetizing oscillating circuit 40, the recharging oscillating circuit 50 is again ready to emit another recharging pulse C to it. The controller 70 opens the oscillating circuit charging switch 31 again briefly at the right point in time, much shorter than a quarter period of the resonance oscillation. This process is repeated until the energy in the reloading memory 60 is exhausted.

It must be ensured that the reloading pulses C each have the correct sign. This must change alternately. As shown in FIG. 5, resonant circuit 50 preferably includes a recharging coil 51 and a recharging capacitor 52 arranged in series therewith. In order to change the polarity, a polarity reversing switch 53 can preferably be arranged parallel to the recharging coil 51 and to the recharging capacitor 52, for reversing the polarity of the charge in the recharging capacitor 52 during a half-oscillation. After every second charge of the recharging capacitor 52, the reversing switch 53 is opened during a half-cycle so that the polarity in the recharging capacitor 52 changes.

Alternatively, a cross switch can also be provided between the recharging memory 60 and the recharging oscillating circuit 50 in order to charge the recharging capacitor 52 in the opposite direction with every second charge.

In the method according to the invention for generating a decaying electromagnetic field, an electronic circuit 10 described here is used to demagnetize ferromagnetic material during a decay time. First, the degaussing oscillating circuit 40, the recharging oscillating circuit 50 and the recharging memory 60 are charged by the voltage source 20, while the charging switch 33, the recharging switch 32 and the oscillating circuit charging switch 31 are closed.

Then said switches 31, 32, 33 are opened again. The resonant oscillation is started at its natural frequency and with a decaying amplitude, for example by the resonant circuit switch 43 being closed. A magnetic, periodic demagnetizing alternating field appears.

Next, by briefly closing and opening the oscillating circuit charging switch 31, a short, first recharging pulse C in the form of a recharging current is introduced from the recharging oscillating circuit 50 into the demagnetizing oscillating circuit 40.

The recharging resonant circuit 50 is then charged by the recharging memory 60 by briefly closing and opening the recharging switch 32 . The last two steps are repeated until the energy reserve in the reloading memory 60 is exhausted.

In a preferred method, each first recharging pulse C is followed by one or more further short recharging pulses C with the same sign and are transmitted to the demagnetizing oscillating circuit 40 . The total duration of the series of recharging pulses C is at most a quarter, preferably at most an eighth, of an oscillation period of the demagnetizing oscillating circuit 40. Each first recharging pulse C preferably flows into the resonant oscillation of the demagnetizing resonant circuit 40 directly after a zero crossing of the resonant circuit voltage A. Since the resonant circuit voltage A changes the sign as a result, the sign of each next first recharging pulse C must also be changed accordingly. In order to achieve this, the polarity of the charge in the recharging capacitor 52 is reversed. This can be achieved by reloading. -Resonant circuit 50 is provided with a reversing switch 53. When the recharging switch 32 is open and the resonant circuit charging switch 31 is open, the polarity reversal switch 53 is closed, resulting in a resonant oscillation of the capacitor 52 and the recharging coil 51 in the recharging resonant circuit 50, which is interrupted again after a half-oscillation by opening the polarity reversal switch 53. Each first recharging pulse C therefore preferably begins exactly half a period of the resonant oscillation of the demagnetizing oscillating circuit 40 later than the preceding first recharging pulse C.

At or before the start of the method, a ferromagnetic workpiece is brought into the effective range of the demagnetizing oscillating circuit 40 in order to demagnetize it. If necessary, the process described here can be repeated several times.

The circuit 10 described here and the method carried out with it allow simple and reliable demagnetization of ferromagnetic bodies. The circuit consists of simple components that allow for a safe, trouble-free process.

Reference List

10 electronic circuit; circuit

20 voltage source

30 conductor loop

31 resonant circuit charging switch

32 reload switch

33 charging switch

34 rectifier diode

40 degaussing resonant circuit

41 degaussing coil

42 vibration capacitor

43 resonant circuit switch

50 Reload Oscillating Circuit

51 reload spool

52 recharge capacitor

53 reversing switch

60 reload memory

62 storage capacitor

70 control

A resonant circuit voltage

B demagnetizing current

C reload pulse

D zero crossing, zero point t time

Claims

patent claims

English Electronic circuit (10) for degaussing ferromagnetic material by resonant oscillation with a prolonged decay time, comprising a) a voltage source (20) and a conductor loop (30) connected thereto, b) a degaussing oscillating circuit (40) in the Conductor loop (30) to form a decaying, alternating magnetic field in which ferromagnetic material can be demagnetized during a decay time (t), c) an oscillating circuit charging switch (31) in the conductor loop (30), in series with the demagnetizing oscillating circuit (40), d) a recharging oscillating circuit (50) in the conductor loop (30), arranged parallel to the demagnetizing oscillating circuit (40) and to the oscillating circuit charging switch (31), for pulsed recharging of a charging current into the demagnetizing oscillating circuit (40 ) with the resonant circuit charging switch (31) closed in each case, e) a recharging memory (60) which is parallel to the voltage source (20), to the recharging resonant circuit (50) and to En demagnetizing oscillating circuit (40), for supplying energy to the recharging oscillating circuit (50) during the decay time (t), f) a recharging switch (32) in the conductor loop (30) for interrupting a charging current from the voltage source (20) and from reloading store (60) to the reloading resonant circuit (50) and to the demagnetizing resonant circuit (40), g) a charging switch (33) for interrupting the charge source (20) to the reloading store (60), to the reloading resonant circuit (50 ) and to the demagnetizing oscillating circuit (40), wherein the voltage source (4) and all switches (31, 32, 33, 43, 53) can be controlled by a controller (70), and in operation by opening and closing the switch (31, 32, 33, 53) recharging pulses (C) from the recharging oscillating circuit (50) can be introduced into the demagnetizing oscillating circuit (40) to extend the decay time until the energy from the recharging storage (60) has been used up .

2. Circuit (10) according to claim 1, characterized in that the degaussing resonant circuit (40) comprises a degaussing coil (41) and a resonant circuit switch (43) in series therewith, and a resonant circuit capacitor (42) arranged parallel to these.

3. Circuit (10) according to claim 1 or 2, characterized in that the reloading memory (60) comprises a storage capacitor (62). Circuit (10) according to Claims 2 and 3, characterized in that the capacitance of the storage capacitor (62) is at least twice as large, preferably at least three times as large as that of the resonant circuit capacitor (42). Circuit (10) according to one of the preceding claims, characterized in that the natural frequency of the recharging oscillating circuit (50) is at least 10, preferably at least 100 times greater than the natural frequency of the demagnetizing oscillating circuit (40). Circuit (10) according to one of the preceding claims, characterized in that the after-charging resonant circuit (50) comprises an after-charging coil (51) and an after-charging capacitor (52) arranged in series therewith. Circuit (10) according to Claim 6, characterized in that a polarity reversing switch (53) is arranged in the recharging resonant circuit (50) parallel to the recharging coil (51) and to the recharging capacitor (52), for reversing the polarity of the charge in the recharging capacitor (52) in a Half-oscillation, with the recharging switch (32) and resonant circuit charging switch (31) open. Circuit (10) according to one of the preceding claims, characterized in that a rectifier diode (34) is arranged in the conductor loop (30) in series with the voltage source (20) and the charging switch (33) in such a way that during use it is fed back from the Can prevent reloading memory (60), from reloading resonant circuit (50) and from demagnetizing resonant circuit (40) in the voltage source (20). Circuit (10) according to one of the preceding claims, characterized in that the voltage source (20) is the only voltage source in the circuit (10). Method for generating a decaying electromagnetic field using an electronic circuit (10) according to one of the preceding claims, wherein ferromagnetic material can be demagnetized in this field during a decay time (t), with the following steps a) charging the demagnetizing oscillating circuit (40 ), the resonant circuit (50) and the recharge memory (60) by the voltage source (20), while the charging switch (33), the recharging switch (32) and the resonant circuit charging switch (31) are closed, b) opening of the charging switch (33), the recharging switch (32) and the oscillating circuit charging switch (31) and set in motion a resonant oscillation in the demagnetizing oscillating circuit (40), which adjusts itself with its natural frequency and with a decaying amplitude and a magnetic, periodic demagnetizing alternating field generated, c) Brief closing and opening of the oscillating circuit charging switch (31), as a result of which a first recharging pulse (C), which is short compared to the resonance oscillation, flows from the recharging oscillating circuit (50) into the demagnetizing oscillating circuit (40), d) Brief closing and opening the recharging switch (32) for charging the recharging resonant circuit (50) through the recharging memory (60), e) repeating steps c) and d) until the energy reserve in the recharging memory (60) is exhausted. Method according to Claim 10, characterized in that in step c) subsequent to the first recharging pulse, one or more further short recharging pulses (C) with the same sign are transmitted to the demagnetizing oscillating circuit (40), the total duration of these recharging pulses being at most a quarter, is preferably at most one eighth of an oscillation period of the resonant oscillation. Method according to Claim 10 or 11, characterized in that the first recharging pulse (C) flows into the resonant oscillation of the demagnetizing resonant circuit (40) immediately after the zero crossing of the resonant circuit voltage (A). Method according to one of Claims 10 to 12, characterized in that in step e) the sign of the first recharging pulse (C) changes with each repetition of step c). Method according to Claim 13 with reference back to Claim 7, characterized in that the polarity of the charge in the recharging capacitor (52) is reversed by the polarity reversal switch (53) being closed when the recharging switch (32) and the resonant circuit charging switch (31) are open, as a result of which a Resonant oscillation of the capacitor (52) and the recharging coil (51) in the recharging resonant circuit (50) sets, which is interrupted again after a half-cycle by opening the reversing switch (53). Method according to Claim 13 or 14, characterized in that each subsequent step c) begins exactly after half a period of the resonance oscillation. Method according to one of Claims 10 to 15, in which, at or before the start of the method, a ferromagnetic workpiece is brought into the effective range of the demagnetizing oscillating circuit (40) in order to demagnetize it. A method according to any one of claims 10 to 16, wherein the process is repeated a number of times. A method according to any one of claims 10 to 17 when dependent on claim 2, wherein the resonant oscillation is initiated by closing the resonant circuit switch (43).