EP2932733A1

EP2932733A1 - Magnet system for a loudspeaker, magnetizing device, method for producing a magnet system and loudspeaker

Info

Publication number: EP2932733A1
Application number: EP13708670.8A
Authority: EP
Inventors: Norman Gerkinsmeyer
Original assignee: Blaupunkt Technology GmbH
Current assignee: Blaupunkt Technology GmbH; GERKINSMEYER, NORMAN
Priority date: 2012-12-12
Filing date: 2013-02-15
Publication date: 2015-10-21
Anticipated expiration: 2033-02-15
Also published as: US20170332173A1; EP2932733B1; WO2014090346A1

Abstract

The invention relates to a magnet system with at least one permanent magnet unit, in particular for use in a loudspeaker, wherein the permanent magnet unit consists of an interconnected combination of at least a first permanent magnet (5) having a first magnetic remanence and a second permanent magnet (4) having a second magnetic remanence, the second magnetic remanence being substantially higher, preferably at least twice as high as the first magnetic remanence.

Description

description

Magnetic system for a loudspeaker, magnetization device, method for producing a magnet system and loudspeaker

The invention relates to a magnet system for a

Speaker, a magnetization device for such a magnet system, a method for producing a

Magnetic system and a speaker with such a

Magnet system.

Magnetic systems with a predominantly annular air gap are generally known in the field of electromagnetic / dynamic sound transducers, actuators and exciters, but are also found in other types of electromagnetically driven systems with an air gap, such as an air gap. Motors, generators and drives in the area of land, water and air, use. Basically, the challenge arises again and again the existing systems in compliance with the

To reduce the efficiency. Magnetic systems increasingly rely on particularly powerful permanent-magnetic materials, for example in the field of rare earths. However, this creates the

Problem that such magnet systems with so-called

Super magnets with extremely high magnetic remanence become very expensive. It is an object of the invention to realize a particularly small-sized magnet system, the smallest possible amounts of materials with particularly high magnetic

Remanence needed. This task is characterized by the characteristics of the independent

Claims solved. Advantageous developments of the invention are the subject of the subordinate claims.

CONFIRMATION COPY The inventor has recognized that a magnet system constructed of a skillful combination of conventional ferrite material and a rare earth magnet achieves nearly the same performance with the same size as that constructed by a purely rare earth magnet Magnetic system can reach. Basically, this inventive consideration applies ^' for the combined

Use of expensive and very powerful

Permanent magnets with inexpensive conventional

Permanent magnets of lower power.

Conventionally, magnetic systems with only one

Magnetic type equipped. So either NdFeB = Neodymium Iron Boron, or Barium Ferrite, Sm ₂ Co = Samarium Cobalt, Strontium Ferrite, AINiCo Magnetic Materials are used by themselves depending on application, specifications and budget.

If the existing system should then be too weak, usually magnetic material is subsequently used, mounted, glued or grouped. However, the additional magnets are to be used only with considerable effort, that is, both the existing and the additionally used magnets are usually already magnetized and must be repulsively mounted or glued opposite polarity.

As a rule, the overall system increases in height (when viewed horizontally, see, for example, Figures 1 & 3), in weight, in the cost and is, compared to

Multimagnets according to the invention, substantially ineffective.

The inventive multi-magnet is at comparable or higher field strength of a ferrite magnet with Y35 material smaller by more than 30% but only slightly more expensive if the inventive manner of construction, and the

technical condition of magnetization or device according to the invention is taken into account. Thus, the specific properties of the various magnetic materials can be specifically combined with the multimagnete according to the invention. An example:

Ferrite magnets have a much higher

Temperature resistance but also volume requirements as e.g.

NdFeB magnets. NdFeB magnets, in turn, have a much stronger field with significantly lower mass than ferrite magnets, but are thermally significantly less resilient. It is suggested that the higher mass of ferrite than

To use heat sink or cooling medium for the example used NdFeB magnet. Combined results in an ideal magnet system in the ratio mass or volume to field strength. However, the reverse is true for volume or mass for the price. NdFeB is e.g.

meanwhile much more expensive while ferrite magnets are quite cheap and price stable. The situation is similar for AINiCo and Sn ^ Co which according to the invention instead of NdFeB

can use. With Sm ₂ Co or AINiCo even high temperature stable multimagnetes according to the invention could be

produce .

However, there are other points that speak for the use of the multi-magnet of the invention, such as e.g. a much better course or better distribution of

Field lines and he is less price fluctuation sensitive.

Especially in times of artificial scarcity

Commodities and their price manipulation by speculation in the world markets, the prices in the commodity sector for rare earths, cobalt, strontium, barium, boron, etc. increased more than 10-fold in the last 2 years.

Another improvement is the use of so-called short-circuit rings, which are preferably arranged above and below the plane of the pole plates, or of additional caps or rings which surround or enclose the pole plate. In both cases come non-magnetic but most electrically very conductive materials, such as copper, brass, aluminum, etc., are used.

It is recommended to use the two shorting rings in systems with larger amplitudes or movements, while the "cap" or the "ring" is more likely to be used on systems with low amplitudes

Amplitudes or movements should be used.

The mode of action of both types of rings is basically the same. It should be prevented that the static magnetic field in the air gap of the multi-magnet according to the invention by the alternating field of the traversed with AC voltage

Voice coil is irritated or modulated, as this can lead to considerable audible and measurable distortions when used in speakers.

In other words, the alternating field of the voice coil induces a current in the rings, thereby reducing the inductance of the voice coil. The so

accompanying increase in impedance towards higher frequencies is almost eliminated and thus the modulation of the magnetic field in the air gap is almost prevented.

Thus, the multi-magnet system according to the invention represents the alternative to existing permanent magnet systems with not only annular air gap.

According to the principles of the above described

Invention, the inventor proposes the variants of the invention described below as particularly favorable embodiments:

AA) magnet system with at least one permanent magnet unit, in particular for use in a loudspeaker, wherein the permanent magnet unit of an interconnected

Combination of at least one first permanent magnet with a first magnetic remanence and a second Permanent magnet with a second magnetic remanence, wherein the second magnetic remanence is much larger, preferably at least twice as large as the first magnetic remanence.

AB) magnet system according to the embodiment AA), wherein the first permanent magnet is formed as a ferrite magnet and / or the second permanent magnet is formed as a rare earth magnet.

AC) magnet system according to one of the embodiments AA) or AB), wherein both permanent magnets each ring-shaped rotationally symmetrical and are arranged coaxially about a common axis of symmetry.

AD) magnet system according to one of the embodiments AA) to AC), wherein both permanent magnets are connected on one side via a conclusion.

AE) magnet system according to one of the embodiments AA) to AD), wherein the magnetization of both permanent magnets is formed in the opposite direction with respect to the common axis of symmetry.

AF) magnet system according to one of the embodiments AC) to AE), wherein the magnetization of both permanent magnets simultaneously and with respect to the common axis of symmetry counteracted takes place in the assembled state of the magnet system.

BA) magnet system, in particular according to

Embodiment variant AA), wherein it has at least:

a first permanent magnet having a first magnetic remanence and a first pole plate connected thereto,

a second permanent magnet having a second magnetic remanence substantially higher, preferably at least twice as high, as the first remanence of the first permanent magnet, and a second pole plate connected thereto a conclusion between the first permanent magnet and the second permanent magnet,

- And an air gap to form a high

Magnetic flux between the first pole plate and the second pole plate.

BB) magnet system according to the embodiment BA), wherein the magnet system is rotationally symmetrical.

BC) magnet system according to one of the embodiments BA) to BB), wherein the first permanent magnet is a ferrite magnet

BD) magnet system according to one of the embodiments BA) to BC), wherein the second permanent magnet is a rare earth magnet.

BE) magnet system according to one of the embodiments BA) to BD), wherein the return has an L-shaped cross-section, each leg of the L with one of the

Permanent magnet is connected, so that a ring-shaped

Air gap between the first permanent magnet and the second permanent magnet including a leg of the L is formed.

BF) magnet system according to one of the embodiments BA) to BE), wherein the pole plates are arranged concentrically to one another and each on a permanent magnet, so that the air gap is formed between them.

BG) magnet system according to one of the embodiments BA) to BF), wherein the mass of the second permanent magnet between 50% and 5%, preferably between 30% and 5%, preferably between 20% and 5%, preferably between 10% and 5%, having the mass of the first permanent magnet.

BH) magnet system according to one of the embodiments BA) to BG), wherein the second permanent magnet is a magnet type from the following list: neodymium-iron-boron, barium ferrite, samarium cobalt, strontium ferrite, aluminum-nickel-cobalt. BI) magnet system according to one of the embodiments BA) to BH), wherein the magnet system has a central opening.

BJ) magnet system according to one of the embodiments BA) to BI), wherein on at least one pole plate at least one short-circuit ring is arranged with a non-magnetic and electrically conductive material.

BK) magnet system according to one of the embodiments BA) to BJ), wherein at least one pole plate by a,

preferably inside open, short-circuit cap or

Short circuit blank, at least partially covered.

BL) magnet system according to the embodiment BK), wherein the short-circuit cap also covers the second permanent magnet at least partially towards the air gap.

CA) magnetization device for a magnet system, in particular for use in a loudspeaker, in particular according to one of the variants AA) to BL), comprising:

a first magnet coil having a first yoke which penetrates the first magnet coil with one limb and has a second open limb with two ends which form a first air gap,

a second magnet coil having a second yoke which penetrates the second magnet coil with one limb and forms an annular air gap through two ends which run in parallel to one another in an annular manner,

- Wherein the annular-shaped ends of the second yoke each having a coaxial opening, in which engage the ends of the first yoke, so that a common

Air gap arises in the one opposite

magnetizing magnet system can be used.

CB) magnetizing device according to

Variant CA), wherein the first and second

Solenoid such with at least one Connected current / voltage supply that with a simultaneous activation of the magnetic coils in the common air gap, an opposite magnetic field is generated, which is reversely aligned in the gap of the first yoke, as in the gap of the second yoke.

D) Method for producing a magnet system,

in particular according to one of the variants AA) to AF) or BA) to BL) and in particular using a magnetizing device according to one of the

Variants CA) to CB), the following

Manufacturing steps are carried out:

- Assembly of a magnet system of a first and a second not yet premagnetized each

rotationally symmetrical permanent magnet, wherein the permanent magnets are arranged with respect to their axis of symmetry coaxially with each other on different diameters and separated by an air gap

- Insert the magnet system in one

Magnetizing device, which can generate a magnetic field for each permanent magnet at the same time, wherein both magnetic fields are aligned axially in opposite directions,

- Simultaneous axial opposite magnetization of

Permanent magnets by briefly switching on the

Magnetizing device,

- Remove the magnet system with axially opposite directions

magnetized permanent magnet.

E) Method for producing a magnet system,

in particular according to one of the embodiments AA) to AF) and using a magnetization device which generates an axially in the same direction (= not in opposite directions) aligned magnetic field inside, wherein the following manufacturing steps are carried out:

rotationally symmetric permanent magnet, wherein the permanent magnets with respect to their axis of symmetry coaxially with each other different diameters and are separated by an air gap,

- Insert the magnet system in the

Magnetizing device,

simultaneous magnetization of the two permanent magnets in a first axial orientation,

simultaneous impingement of the two permanent magnets by a magnetic field having an opposite direction in the axial direction with a field strength which does not reverse magnetize the first magnet but reversely magnetizes the second magnet to its first magnetization,

- Remove the magnet system with axially magnetized permanent magnet. FA) Method for producing a magnet system,

rotationally symmetric permanent magnets, wherein the permanent magnets are arranged with respect to their axis of symmetry coaxially with each other at different diameters and by an air gap separated from each other,

- Insert the magnet system in the

Magnetizing device,

shielding the first magnet by inserting an electrically conductive shield at least in the air gap,

simultaneous impingement of the two permanent magnets by an opposing magnetic field in the axial direction with time-varying field strength by momentarily switching on a magnetic coil of the magnetization device, wherein the magnetic field strength in the second unshielded magnet is lower than in the first magnet, - Remove the magnet system with axially magnetized permanent magnet.

FB) method according to the above embodiment FA), wherein after the first magnetization and before the second magnetization of the first magnet by inserting an electrically conductive ring in the air gap or a

electrically conductive cap, which at least partially extends into the air gap, is shielded.

FC) method according to the above embodiment FA), wherein after the first magnetization and before the second magnetization of the first magnet an electrically conductive, split ring in the axial direction is used in the air gap and by supplying a current surge during the second magnetization, the external magnetic field is attenuated ,

G) Method for producing a magnet system,

rotationally symmetric permanent magnet, wherein the first

Permanent magnet has a saturation field strength which is smaller than the maximum field strength, from which irreversible losses of the magnetization of the second permanent magnet arise,

- Insert the magnet system in the

Magnetizing device,

simultaneous magnetization of the two permanent magnets in a first axial orientation with a field strength that is greater than the saturation field strength of the second permanent magnet,

- Subsequently, simultaneous application of the two

Permanent magnet by an opposing magnetic field in the axial direction with a field strength greater than that Saturation field strength and smaller than the maximum field strength, from which irreversible losses of the magnetization of the second permanent magnet arise,

- Remove the magnet system with axially magnetized permanent magnet.

HA) magnet system, in particular according to

Embodiment variant AA), wherein it has at least:

a first permanent magnet having a first magnetic remanence,

- One, directly connected to the first permanent magnet second permanent magnet, with a second magnetic

Remanence, which is much higher, preferably at least twice as high as the first remanence of the first

Permanent magnets,

a first pole plate directly connected to the second permanent magnet,

- a conclusion of the first permanent magnet

connected is,

- And an air gap to form a high

Magnetic flux between the conclusion and the first

Pole plate.

HB) magnet system according to the embodiment HA), wherein the magnet system is rotationally symmetrical.

Magnet system according to one of the embodiments HA) HB), wherein the first permanent magnet is a ferrite magnet.

HD) magnet system according to one of the embodiments HA) to HC), wherein the second permanent magnet is a rare earth magnet.

HE) magnet system according to one of the embodiments HA) to HD), wherein the mass of the second permanent magnet between 50% and 5%, preferably between 30% and 5%, preferably between 20% and 5%, preferably between 10% and 5%, having the mass of the first permanent magnet. HF) magnet system according to one of the embodiments HA) to HE), wherein the magnet system has a central opening

HG) magnet system according to one of the embodiments HA) to HF), wherein on the pole plate at least one

Shorting ring is arranged with a non-magnetic and electrically conductive material.

HH) magnet system according to one of the embodiments HA) to HG), wherein the pole plate is at least partially covered by a, preferably inside open, shorting cap or short circuit blank.

HI) magnet system according to the embodiment HH), wherein the short-circuit cap and the second permanent magnet

at least partially covered towards the air gap.

I) Method for the production of a magnet system,

in particular according to one of the embodiments AA) to AF) or HA) to HI), and in particular using a magnetization device according to one of

Variants CA) to CB), the following

Manufacturing steps are carried out:

- Assembling a magnet system of a first and a second not yet premagnetized rotationally symmetric permanent magnet and one, in cross-section L-shaped

formed conclusion, wherein the permanent magnets are arranged coaxially and one above the other and are directly connected to each other and between the back yoke and the permanent magnet an air gap is formed,

- Insert the magnet system in one

Magnetizing device which can simultaneously generate a magnetic field for the permanent magnets on the one hand and the inference on the other hand, both

Magnetic fields are axially aligned in opposite directions and a magnetic field acts on the permanent magnets and a magnetic field acts on a leg of the return path, simultaneous axial magnetization of the permanent magnets by momentarily switching on the opposing magnetic fields of the magnetization device,

- remove the magnet system with magnetized

Permanent magnets.

J) magnet system, produced by a method described here, in particular by a method according to one of the embodiments D) - G).

K) loudspeaker with one of the magnetic systems described herein, wherein the magnetic system

preferably according to one of those described here

Magnetization method was magnetized and produced.

Particularly favorable has instead of the simultaneous counter-rotating magnetization in a single

Magnetization process, the two-phase magnetization proved, in which in a first step the

Multimagnet system with two concentrically arranged on different diameters ring magnets, separated by an air gap, first in a common direction

be magnetized. Subsequently, a reverse magnetization of both ring magnets is carried out such that both

Ring magnets are exposed to the reverse magnetic field, but only one magnet is reversed.

This can be done, for example, that for the magnets each such materials are chosen that they have a substantially different coercivity and the second opposite magnetization with a

Field strength is performed, which reverses the one magnet, the other magnet but not re-magnetized.

As an alternative or supportive to the first embodiment of the magnetization, the magnetic field can be shielded by a magnet during the second counter-rotating magnetization be reduced in the range of one magnet so that no pole reversal takes place while the other magnet is reversed. The shielding can be done by a conductive material in the air gap, which is induced in a pulse-like remagnetization, a counteracting ring current, or it can be active during the remagnetization

counteracting current pulse are generated in the air gap, which also unfolds an opposite effect. The multi-magnet according to the invention will be explained here by way of example on an annular gap magnet for sound transducers.

In the following, the invention is based on preferred

Embodiments of an annular gap magnet for

Sound transducer with the help of figures described in more detail, with only the necessary features for understanding the invention features are shown.

In detail show:

1: Multimagnet system with two concentric

arranged ring magnets of different remanence;

2 shows a multi-magnet system from FIG. 1 in plan view;

3: magnetizing device for simultaneous

opposite magnetization in section;

FIG. 4: magnetization device from FIG. 3 in FIG

Top view;

FIG. 5: stray field magnetizer with magnet system according to FIG

1 in section;

FIG. 6: stray field magnetizer with magnet system according to FIG

1 with additional shielding in section; FIG. 7: stray field magnetizer with magnet system according to FIG

1 with active shielding in section;

FIG. 8: stray field magnetizer from FIG. 7 in section A-A; FIG. 9: magnet system according to FIG. 1 during the

Magnetization according to step II, shielding the inner magnet; FIG. 10: Illustration of the magnetization against external. FIG

Magnetic field strength;

FIG. 11: Time field strength course during the steps. FIG

I and II of magnetization with passive shielding;

FIG. 12: Time field strength course during the steps. FIG

I and II of magnetization with active

Shielding;

FIG 13: variant of the multi-magnet with

Short-circuit ring;

FIG. 14 shows a variant embodiment of the multimagnet with FIG

Copper cap;

FIG. 15: Size comparison of a magnet system according to the prior art

Technology and a multi-magnet according to the invention; FIGS. 16-18: size comparison of the magnet systems in relation to the achievable field strength in the air gap;

FIG. 19: Multimagnet as pot magnet system with cup-like

Conclusion;

FIG. 20: stray field magnetizer with magnet system according to FIG

19;

FIG. 21: Multimagnet as pot magnet in the design with two short-circuiting rings; FIG.

FIG. 22: Multimagnet as pot magnet in the version with

Short circuit cap.

FIG. 1 shows an example of the invention

Multimagnets as a ring magnet system, with its outer

Polplatte 1 which sits on the ferrite magnet 5 and

preferably, but not necessarily, has a slightly smaller inner diameter than the ferrite magnet. Of the

Air gap 2 is now given by the inner diameter of the outer pole plate 1 relative to the outer diameter of the inner pole plate 3, based on the example

used NdFeB magnet 4, which in turn is on the so-called T-yoke or yoke with yoke 6, which also has an optional center hole 7, on the one hand the ventilation on the other hand serve the better management of the field line course in the air gap 2 of the system can. It has proved to be particularly favorable, but not mandatory, to perform the inner pole plate 3 slightly more projecting and higher than the outer pole plate 1. Furthermore, it has proven to be particularly advantageous, the outer diameter of the inner pole plate 3 is greater than the underlying diameter of the example

NdFeB magnets 4 and the so-called T-yoke or yoke 6 to be executed. The preferably

executed phases at the edge of the pole plate 1 or depressions of the center or through hole serve on the one hand the

Improvement of the field line course and on the other hand a prevention of the noise development by displaced or

flowing through gaseous media, e.g. Air.

Should the magnet volume and especially the diameter (also applies to the variants of FIGS. 11 & 12) in the core and

Air gap 2 and thus also the used NdFeB magnet 4 with its pole plate 3 by design to be too small, it may be advantageous to apply no center hole 7 with phases. A reduction in the form of the phase, as in the center hole 7, may under certain circumstances make sense, since an improvement in the field line course is accompanied by a reduction in the pole plate 3 and 6 conclusion.

Through various attempts in the course of development has been found that it may be cheaper, depending on the size and requirement of the system, to position the position of the example used NdFeB magnet 4 in the example sketched area also centrally or further down. In this case, the inner pole plate 3 would be correspondingly higher or, under certain conditions, completely eliminated.

FIG. 2 shows, in plan view, the cross-sectional view of the multi-magnet according to the invention for FIGS. 1, 3, 5, 6, 7, 9, 12, 13, 16 and 17 for better understanding. In particular, the concentric or coaxial arrangement of the two magnets of different coercivity 4 and 5 of the multi-magnet 19 is illustrated. FIG. 3 shows an example of the invention

Magnetizing device of the multi-magnet 19 according to the invention according to FIG. equipped with NdFeB in the middle. This device consists of a

Exciting coil 15 which can magnetize via a yoke 16, the central region and a ring-shaped executed yoke 17 and its exciting coil 18, the outer region of the multi-magnet 19 according to the invention.

By the inventive technology or the

multimagnetes according to the invention now succeed that the

Magnets of the multi-magnet 19 according to the invention, although they are made of completely different material and normally each would have to be magnetized by itself, can be magnetized together. It is proposed that the coil 15 via its yoke 16, the inner region opposite pole with greater than 2000 kA / m over the outer

Area, is magnetized with the ring-shaped yoke 17 and its exciting coil 18 with greater than 800 kA / m. With this magnetizing device according to the invention, it is also possible to use the multi-magnet according to the invention from FIG. 17 as a pot magnet system, which, e.g. equipped with NdFeB and ferrite in the middle, magnetize. In this case, only the excitation coil 15 with the yoke 16 for the middle

Range, greater than 2000 kA / m are used.

Since the yoke 16 and the yoke 17, the inventive

Multimagnetsystem 19 only covers above and below and not completely surrounds, it is possible, the magnetization device according to the invention in a band-like

Integrate production line. In this case, the band passes through the magnetizing device according to the invention in the region of the multi-magnet system 19 according to the invention, which comprises this positively engages securely and is also able to magnetize normal magnetic systems, since the coils 15 and 18 can also be operated separately and independently.

FIG. 4 shows the magnetizing device according to the invention in plan view. Here, the same reference numerals as in Figure 3 are used. As an alternative to simultaneously oppositely magnetizing the magnet system of FIG. 1 or one of the magnet systems of FIGS. 12 and 13, such a magnet may be used

Magnet system according to the invention also in succession magnetize with a simple magnetizing coil in opposite directions. This procedure is described in more detail in FIGS. 5 to 10.

FIG. 5 shows the magnet system 19 from FIG. 1 in a magnetizing coil 20. Hereby, in a first step, the entire magnet system 19 with the two

concentrically arranged on different diameters magnet 4 and 5 in a common N-S direction

magnetized. In this case, the higher coercive magnet 4 is fully magnetized by an axial field arrangement, the low coercive magnet 5 is partially or fully magnetized in the same direction. The magnetization direction of the magnetization device and the magnets is described by the designation N and S. Alternatively, the axial field can also be realized by a yoke similar to FIG. 3, or by the central or stray field of an axial field coil according to FIG. In addition, the magnetizing coil can also have an inference.

FIG. 6 describes the second step of FIG

Magnetization, wherein the magnet 5 is magnetized in the opposite direction. For that will be the Magnetizing coil 20 operated with respect to the Figure 5 inverted field direction. However, the already magnetized magnet 4 must not be re-magnetized. On the one hand, this can be done by using a correspondingly high-coercivity magnet material for the magnet 4. So that this one has such a higher resistance to one

Re-magnetization has as the magnet 5. In this case, a field is applied, although the magnet 5 ummagnetisiert, but does not change the magnetization of the magnet 4 due to its higher coercivity.

Alternatively, a shield 31 of a highly electrically conductive material (e.g., copper) may be introduced into the air gap of the

Magnet system between the magnets 4 and 5 are immersed. This shield 31 may be formed as a cap, but at least as a ring.

By the short-term energization of the coil 20 eddy currents are generated in the ring, which displace the inverse field for the magnet 4 and reinforce the field for magnetization reversal of the magnet 5. In this way, the

Magnetization direction of the magnet 5 inverted, while the magnetization of the magnet 4 is maintained.

As can be seen from the registered magnetization alignments N and S, the magnetization of the

Magnets 4 and 5 opposite after the second step. Another variant of the second step of

magnetization according to the invention is shown in Figures 7 and 8. Here instead of the passive

Magnetic field weakening through a conductive ring in the

Air gap of the multimagnet or a corresponding

conductive cap an actively energized in the axial direction with the gap 32 split ring 31 inserted into the air gap between the magnets 4 and 5 and when turning on the external inverted magnetic field through the magnetizing coil 20 so energized that a magnetic field counteracting the external magnetic field of the magnetizing device is formed. This internal magnetic field then causes a reduction of the field strength of the external magnetic field and prevents the magnetic reversal of the magnet 4, while it promotes the magnetic reversal of the magnet 5.

FIG. 7 shows the magnetizing coil 20 with the multi-magnet arranged therein in an axial section, while FIG. 8 shows the section A-A through the coil 20.

As shown in Figure 8, at the moment of

Magnetic reversal of the magnet 5 by applying voltage to the split ring 31 generates a current in the air gap, which in turn generates a magnetic field - represented by outside the

Ringes 31 emerging from the art surface six arrows and the inside of the ring 31 six in the drawing surface entering arrows - generated, which promotes the re-magnetization of the outer magnet 5, but counteracts the remagnetization of lying within the ring 31 magnet 4.

In the above described reversal magnetization in the second

Step with an oppositely directed, actively generated magnetic field, the current pulse through the ring must be synchronized in time with the current through the outer coil. It is possible depending on the size of the magnet system to transform the ring current through a current transformer high or switch in series with the outer coil. To illustrate the in the magnet system 19 during the

Ummagnetisierung of the outer magnet 5, that is, during the second step, the present magnetic field is again shown in Figure 9, the multi-magnet 19 in section, wherein additionally the magnetic field directions and the magnetic field lines are shown. It can be seen that the external magnetic field in the magnet 4 is weakened and the external magnetic field in the magnet 5 is amplified by the inserted ring 31 and the ring current generated there. Accordingly becomes the magnet 5 is reversely aligned while the magnet 4 has its initial impressed in the first step

Maintains magnetization direction. This is still in the figure 10 for two

different materials - corresponding to the magnets 4 and 5 - the magnetization M in relation to an external Magnetisierfeidstärke H applied in the form of a hysteresis loop. For example, the magnet 4 the

consistent course, where up to one

Field strength H greater H4 magnetization in the magnet 4 remains, then after a permanent weakening begins until the polarity reversal. Accordingly, the course of the magnetization M is dotted for a

Material of the magnet 5 shown. In this way, in principle, two magnets of different coercivity can be reversely polarized side by side with the same applied magnetic fields. If Hs5 <H4, no shielding for the magnet 4 in the second step is needed.

According to the invention, the selection of the magnetic materials with respect to the ratio Hs5 to H4 is extended by additionally shielding the magnet 4 which is not to be reversed against the magnetizing magnetic field, passive or active.

Such a process is illustrated in FIGS. 11 and 12 by plotting the acting field strength H over the time axis t.

FIG. 11 shows the steps I and II of the magnetization by a magnetization device according to FIGS. 5 and 6 with passive shielding. In step I, the two magnets 4 and 5 are exposed to an approximately equal field strength curve HI and magnetized next to each other in the same N-S direction magnetized. It will be between the first

Step I and the second step II of the invention Magnetizing a shield or a shield cap placed in the air gap between the magnets 4 and 5. It now follows the step II, in which an opposing

Magnetic field with the curve Hlla in the magnetizing coil erzugt. This field also acts on the unprotected magnet 5 and polts this, since it is larger than his

Saturation field strength Hs5 is completely around. At the same time, however, the magnet 4, which lies inside the shield, is acted upon only by a field strength curve according to Hllb, since the ring current generated in the shield counteracts the external magnetic field in the form of HIIc. The so produced

Field strength curve of the magnetic field HIIb = HIIa-HIIc remains below the limit of H. Accordingly, the magnet 4 is not weakened and both magnets get in already

assembled state their oppositely directed fully saturated magnetization.

FIG. 12 shows the inventive steps I and II of the magnetization by a magnetizing device according to FIGS. 5 and 7 or 8 with active

Shielding. In step I, the two magnets 4 and 5 are exposed to an approximately equal field intensity HI and mounted side by side in the same N-S direction

magnetized. Then, between the first step I and the second step II of the magnetization according to the invention, an actively energizable ring is placed in the air gap between the magnets 4 and 5, as shown in FIGS. 7 and 8. It now follows the step II, in which an opposing magnetic field with the curve Hlla in the

Magnetizing device is generated. This field acts on the unprotected magnet 5 and poles it completely because it is larger than Hs5. At the same time, however, voltage is applied to the ring 31 and a ring current in

Air gap generated, the one opposing

Field strength course generated according to HIIc and within the

Magnets 4 leads to a field strength Hllb. Since the magnetic field generated within the shield remains below the limit of H4, there is no weakening of the magnet 4 and both magnets get in the already assembled

State their oppositely directed fully saturated magnetization, as shown in FIG. Further embodiments of a multi-magnet according to the invention are shown in FIGS. 13 and 14. FIG. 13 shows the multi-magnet according to the invention in the embodiment with two short-circuiting rings 22 - above and in the outer edge of the inner pole plate 3 - and 23 - below the outer pole plate 1 -. The shorting rings 22 and 23 are preferably made of aluminum, copper or brass. But it is also possible that the short-circuit ring 22 is above the outer

Polplatte 1, and thus the same or similar inner and outer diameter as the short-circuit ring 23 has.

FIG. 14 shows the multi-magnet according to the invention in the embodiment with the so-called copper cap 24, which can optionally consist of aluminum, copper or brass. In this example, it encloses the yoke of the yoke 6 or T-yoke, with the optional NdFeB magnet 4 and its inner pole plate 3. Preferably, the copper cap in this case also has a hole corresponding to the through hole 7 with phases. But it is also conceivable to perform the copper cap 24 as a ring, which merely encloses the inner pole plate 3 or slightly covered over the height down and up.

FIG. 15 shows the possible size savings of

according to the invention with respect to a multi-magnet system

conventional ferrite magnet system. The reference numeral 13 designates a magnetic system equipped exclusively with ferrite magnets, while the reference numeral 14 (hatched area) the same magnet system, but with the

represents combination according to the invention of different types of magnets in cross section. In FIGS. 16 to 18, a size comparison of FIG

Magnet systems in relation to the achievable field strength shown in the air gap.

FIG. 16 shows a standard ferrite magnet with its field strength profile measured across the thickness in the annular air gap 30.

FIG. 17 shows an optimized invention which has already been reduced by a quarter in height or thickness

Multimagneten according to Figure 1, for example with a NdFeB magnet 4 and thinner ferrite magnet 5, with inner

Polplatte 3 and outer pole plate 1 and his

Field strength course, in about the thickness in the annular

Air gap 2 measured. In this case, one recognizes a significantly higher and above all more linear course than in the curve in FIG. 16.

FIG. 18 shows a highly optimized multimagnet according to the invention according to FIG. 1, by way of example with an even thinner NdFeB magnet 4 and ferrite magnet 5, with inner pole plate 3 and outer pole plate 1 and its

Field strength course, in about the thickness in the annular

Air gap 2 measured. The aim here was to produce the same strong field as in FIG. 8. It can be seen that the course is still much more linear and slightly higher than in the standard magnet in Figure 8. This is achieved, although only half of the volume and mass of magnetic material is used.

According to the basic idea of the invention, according to which a reduction of the magnet system, in particular for a loudspeaker, by a permanent magnet unit consists of a combination of at least a first permanent magnet with a first magnetic remanence and a second permanent magnet with a second one

magnetic remanence is achieved, wherein the second magnetic remanence is much larger, preferably At least twice as large as the first magnetic remanence, another variant of a magnetic system according to the invention is shown in the following figures 19-22. FIG. 19 shows an example of the invention

The air gap 9 is now given by the inner diameter of the pot-shaped yoke 12 with respect to the outer diameter of the pole plate 10, which is based on the example used NdFeB magnet 11, which in turn on the ferrite magnet 29th located, which also has an optional central bore 8, on the one hand the

Ventilation on the other hand, the better management of

Field line course in the air gap 9 of the system can serve. It has proved to be particularly favorable, the

Pole plate 10 slightly protruding and / or higher than the height of the pot-shaped yoke 12th

If the magnet volume and above all the diameter in the core and air gap 9 and therefore also the NdFeB magnet 11 used with its pole plate 10 are too small due to the design, it may be advantageous not to use a central bore 8 with phases. A reduction in the form of the phase as in the center hole 8 may under some circumstances still make sense, as well as with a reduction in the pole plate 10 and pot-shaped conclusion 12 an improvement of

Feldlinienverlaufes goes along.

Furthermore, it has proven to be particularly advantageous to make the outer diameter of the pole plate 10 greater than the diameter of the underlying, for example, used NdFeB magnet 11 and the ferrite magnet 29. The preferably executed phases at the edges of

cup-shaped conclusion 12 or subsidence of the center or through hole serve on the one hand to improve the

Field line course and on the other hand, a prevention of noise by displacing or flowing through gaseous media, such as air. Depending on the size and requirement of the system, it may also be more favorable to turn the position of the NdFeB magnet 11 and ferrite magnet 29 used, for example, in the area sketched by way of example, to position centrally or both magnets further down. In this case, the pole plate 10 would be correspondingly higher or lower

certain conditions can be completely eliminated. FIG. 20 shows a magnetizing device, as already shown in FIGS. 5 to 8, in one

Execution as a stray field magnetizing coil 20, with which also the magnet system according to the invention according to FIG. 19 can be magnetized, which is optionally connected e.g. equipped with NdFeB and ferrite in the middle, and is designed as a pot magnet system. It should be for magnetization

Stray field greater than 2000 kA / m are used.

FIG. 21 shows a multimagnet according to the invention as a pot magnet in the embodiment with two short-circuit rings 25 -including and in the outer edge of the pole plate 10 -and 26- below the NdFeB magnet 11 used by way of example. The shorting rings 25 and 26 are preferably made of aluminum, copper or brass. But it is also possible that the short-circuit ring 25 can be located above or on the edge of the pot or yoke 12.

FIG. 22 shows the multi-magnet according to the invention as a pot magnet system in the embodiment with the so-called

Copper cap 27 made of aluminum, copper or

Brass can exist. In this example, it encloses the ferrite magnet 29, the optional NdFeB magnet 11, and its pole plate 10. Preferably, in this case too, the copper cap has a hole corresponding to that of FIG

Through hole 8 with phases. It is also possible here to carry out the copper cap 27 as a ring which merely encloses the pole plate 10 or covers it slightly above and below the height. If the magnet volume and above all the diameter in the core and air gap 9 and therefore also the NdFeB magnet 11 used with its pole plate 10 are too small due to the design, it may be advantageous not to use a central bore 8 with phases. A reduction in the form of the phase as in the center hole 8 may under some circumstances still make sense, as well as with a reduction in the pole plate 10 and pot-shaped conclusion 12 an improvement of

Feldlinienverlaufes goes along.

Overall, the invention thus proposes a magnet system with at least one permanent magnet unit, in particular for use in a loudspeaker, wherein the

Permanent magnet unit of an interconnected

Combination of at least one first permanent magnet with a first magnetic remanence and a second

Permanent magnet with a second magnetic remanence and the second magnetic remanence is much larger, preferably at least twice as large as the first magnetic remanence.

Furthermore, the invention relates to a magnetization ^¬ device for such a magnet system, which can be operated by means of two simultaneously by separate coils

Yoke systems can build two parallel and oppositely oriented magnetic fields, wherein the first magnetic field concentrically surrounds the second magnetic field like a thick cylinder jacket an inner cylinder.

Moreover, the invention relates to a method for producing and magnetizing the o.g. Magnet system with the o.g.

Magnetizing device and a speaker with a magnet system according to the invention.

Although the invention in detail by the preferred

Example has been illustrated and described in more detail, the invention is not by the disclosed examples and other variations can be deduced therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

I outer pole plate

2 air gap

3 inner pole plate

4 NdFeB magnet

5 ferrite magnet

6 conclusion

7 Center hole / center hole / through hole

8 center hole / center hole / through hole

9 air gap

10 pole plate

II NdFeB magnet

12 conclusion

13 magnet system according to the prior art

14 magnet system according to the invention

15 coil

16 yoke

17 yoke

18 coil

19 multi-magnet

20 stray magnetic field coil

22 short circuit ring

23 short-circuit ring

24 copper cap

25 short-circuit ring

26 short-circuit ring

27 copper cap

28 multi-magnet

29 ferrite magnet

30 air gap

31 shield / ring / cap

32 gap

I first step of magnetization

11 second step of the magnetization H magnetic field strength

H4, H5 maximum field strength from which the magnets 4 and 5 irreversible losses of magnetization arise

Hs4, Hs5 Saturation field strength of magnets 4 and 5 from which full magnetization occurs

HI course of the magnetic field strength in step I

Hlla course of the magnetic field strength in step II in a first magnet

Hllb course of the magnetic field strength in step II in a second magnet

HIIc course of the magnetic field strength in step II by induced ring current

M magnetization

Claims

claims

1. magnet system with at least one permanent magnet unit, in particular for use in a loudspeaker, characterized in that the

Permanent magnet unit of an interconnected combination of at least one first permanent magnet (5) with a first magnetic remanence and a second permanent magnet (4) with a second

magnetic remanence, the second magnetic remanence being much larger,

preferably at least twice as large as the first magnetic remanence.

2. magnet system, in particular according to the preceding claim 1, characterized in that it comprises at least:

2.1. a first permanent magnet (5) with a first

magnetic remanence and a first pole plate (1) connected thereto,

2.2. a second permanent magnet (4), with a second

magnetic remanence, which is much higher

preferably at least twice as high as the first remanence of the first permanent magnet (5), and a second pole plate (3) connected thereto,

2.3. a conclusion (6) between the first permanent magnet

(5) and the second permanent magnet (4),

2.4. and an air gap (2) for forming a high

Magnetic flux between the first pole plate (1) and the second pole plate (3).

3. magnetization device for a magnet system,

in particular for use in a loudspeaker, in particular according to one of the preceding claims 1 to 2, comprising:

3.1. a first magnet coil (15) having a first yoke (16) with one limb, the first magnet coil (15) penetrates and a second open leg having two ends forming a first air gap, a second magnetic coil (18) having a second yoke

(17), which with one leg the second magnetic coil

(18) penetrates and through an annular annular parallel to each other formed ends

Air gap forms,

wherein the annularly shaped ends of the second yoke (17) each have a coaxial opening, in which engage the ends of the first yoke (16), so that a common air gap is formed, in which a counter magnetizing magnet system can be used.

Method for producing a magnet system,

in particular according to one of the preceding

Claims 1 to 2 and in particular under

Use of a magnetizing device according to claim 3, characterized in that the following manufacturing steps are carried out: assembling a magnet system comprising first and second non-premagnetized respectively rotationally symmetric permanent magnets (5, 4), the permanent magnets (5, 4) with respect to their Symmetry axis coaxial with each other on different diameters and by an air gap (2) are arranged separately from each other

insert the magnet system into one

Magnetizing device, which can simultaneously generate a magnetic field for each permanent magnet (5, 4), wherein both magnetic fields axially

are oriented in opposite directions,

simultaneous axially opposing magnetization of the permanent magnets (5, 4) by briefly switching on the magnetization device,

take the magnetic system with axially opposite magnetized permanent magnet (5, 4).

5. A method for producing a magnet system, in particular according to one of the preceding

Claims 1 or 2 and by using a magnetizing device, which generates in the interior of a axia in the same direction (= not in opposite directions) aligned magnetic field, characterized

ge chneld that the following

Manufacturing steps are carried out:

5.1. Assembling a magnet system comprising a first and a second not yet premagnetized respectively rotationally symmetric permanent magnet (5, 4), wherein the permanent magnets (5, 4) with respect to their axis of symmetry coaxial with each other on different diameters and by an air gap (2) are arranged separately and

5.2. insert the magnet system into the

Magnetizing device,

.3. simultaneous magnetization of the two permanent magnets (4, 5) in a first axial orientation,

.4. Simultaneous loading of the two permanent magnets (4, 5) by an opposing magnetic field in the axial direction with a field strength, which does not reverse magnetize the first magnet (4), but the second magnet (5) opposite to its first

Magnetization re-magnetized,

.5. take the magnet system with axially magnetized permanent magnet (4, 5).

Method for producing a magnet system,

in particular according to one of the preceding

ge chneld that the following

Manufacturing steps are carried out:

.1. Assembly of a magnet system of a first and a second not yet premagnetized respectively rotationally symmetrical permanent magnet (5, 4), wherein the

Permanent magnets (5, 4) are arranged with respect to their axis of symmetry coaxially with each other on different diameters and through an air gap (2) separated from each other and are,

insert the magnet system into the

Magnetizing device,

simultaneous magnetization of the two permanent magnets (4, 5) in a first axial orientation,

shielding the first magnet (4) by inserting an electrically conductive shield (24) at least in the air gap (9),

Simultaneous loading of the two permanent magnets (4, 5) by an opposing magnetic field in the axial direction with changing field strength by momentarily switching on a magnetic coil of the magnetization device, wherein the magnetic field strength in the second, unshielded magnet (5) is lower than in the first magnet (4 )

take the magnet system with axially magnetized permanent magnet (4, 5).

Method according to the preceding claim 6, characterized in that after the first magnetization and before the second

Magnetization of the first magnet (4) by inserting an electrically conductive ring (24) in the air gap (9) or an electrically conductive cap which extends at least partially into the air gap (9) is shielded.

Magnetization of the first magnet (4) an electrically conductive, split in the axial direction ring (24) in the air gap (9) is used and by supplying a Power surge during the second magnetization, the external magnetic field is attenuated.

9. Method for producing a magnet system,

in particular according to one of the preceding

Claims 1 or 2 and using a magnetizing device, which generates an axially in the same direction (= not in opposite directions) aligned magnetic field inside

characterized in that the following

Manufacturing steps are carried out:

9.1. Assembly of a magnet system comprising a first and a second not yet magnetized respectively rotationally symmetric permanent magnet (5, 4), wherein the first permanent magnet (5) has a saturation field strength (Hs5) which is smaller than the maximum field strength (H4), starting from the irreversible losses the magnetization of the second permanent magnet (4) arise,

9.2. insert the magnet system into the

Magnetizing device,

9.3. simultaneous magnetization of the two permanent magnets

(4, 5) in a first axial orientation with a field strength that is greater than the saturation field strength (Hs4) of the second permanent magnet (4),

9.4. subsequently simultaneous loading of the two permanent magnets (4, 5) by an opposing magnetic field in the axial direction with a field strength which is greater than the saturation field strength (Hs5) and less than the maximum field strength (H4), from the irreversible losses of the magnetization of the second permanent magnet ( 4) arise,

9.5. take the magnet system with axially magnetized permanent magnet (4, 5).

10. magnet system, in particular according to the preceding

Claim 1, characterized in that it comprises at least:

10.1. a first permanent magnet (29) having a first magnetic remanence,

10.2. a second permanent magnet (11) directly connected to the first permanent magnet (29), having a second magnetic remanence which is substantially higher, preferably at least twice as high as the first remanence of the first permanent magnet (29),

10.3. a first pole plate (10) directly connected to the

second permanent magnet (11) is connected,

10.4. a conclusion (12) of the first permanent magnet

(29) is connected,

10.5. and an air gap (9) for forming a high

Magnetic flux between the return path (12) and the first pole plate (10).

11. Method for producing a magnet system,

in particular according to one of the preceding

Claims 1 or 10 and in particular under

Use of a magnetizing device according to claim 3, characterized in that the following manufacturing steps are carried out:

11.1. Assembly of a magnet system of a first and a second not yet premagnetized

rotationally symmetrical permanent magnet (29, 11) and one, in cross-section L-shaped

Conclusion (12), wherein the permanent magnets (29, 11) arranged coaxially and one above the other and are directly connected to each other and between the return path (12) and the permanent magnets (29, 11) an air gap (9) is formed,

11.2. insert the magnet system into one

Magnetizing device, which at the same time for the permanent magnets (29, 11) on the one hand and the inference (12) on the other hand can generate a magnetic field, both magnetic fields are aligned axially in opposite directions and a magnetic field on the permanent magnets (29, 11) and a magnetic field acts on a Thighs of the

Inference (12) works,

11.3. simultaneous axial magnetization of the permanent magnets (29, 11) by briefly switching on the

opposing magnetic fields of

Magnetizing device,

11.4. remove the magnet system with magnetized

Permanent magnets (29, 11).

Magnetic system produced by a method according to one of the claims 4 to 8 or 10.

Loudspeaker with a magnet system according to one of claims 1 or 2 or 9.

14. loudspeaker with a magnet system, produced according to claim 11.