DE3152008C1 - Elongated magnetic switching core - Google Patents

Abstract

In an elongated magnetic switching core which can be switched suddenly from one magnetic state into another magnetic state by the application of an external magnetic field, a composite body having at least two parts consisting in each case of different materials is used, at least one of which can be magnetised. The composite body may be constructed as a wire-shaped single-core body or as a multi-core or multi-layer body.

Description

The invention relates to an elongated magnetic switch core, which induces an impulse in a coil surrounding it, if the external magnetic Field exceeds or falls below certain field strength values. How this works Switching core is based on the von Preisach 1929 (F. Preisach: Ann. Phys., Lpz. 3 (1929) pp. 737 to 799) on very long, thin Permalloy wires under tensile stress observed magnetic reversal in a single large Barkhausen jump due to the movement of a 180 ° hole wall. This effect was used by Sixtus and Tonks in one Series of fundamental works in the years 1931 to 1933 examined in detail and described. (See e.g. K. J. Sixtus: In »Problems of technical Magnetization Curve ", edited by R. Becker, Berlin: Springer 1938).

With the tensile stress, uniaxial anisotropy became in the permalloy wire generated, which ensured that for energetic reasons only 1800 Bloch walls appear could. The great length of the wire with a small diameter has the consequence that demagnetizing fields that interfere with the magnetic reversal process due to the small Scatter factor are negligibly small.

The sudden reversal of magnetization due to the rapid movement a 1800-Bloch wall is used in the switching core described in US-PS 3820090 been. This switch core consists, as in US-PS 3892 118 (see also DE-OS 21 43326 and DE-OS 28 19 305) is made from a ferromagnetic wire an iron-cobalt-vanadium alloy, which is complicated to manufacture Pulling and twisting treatment goes through, with the inner and the outer part of the wire assume different magnetic properties despite the same composition. The outer part goes into a permanent magnetic state with increased coercive field strength over, while the inner part takes on soft magnetic properties. It should A tensile stress build up in the inner part of the wire, which becomes uniaxial Anisotropy in the soft magnetic material leads to In a magnetic field parallel to Wire axis, which is made up of an external field of a certain size and that of the permanent magnetic field If the field is composed of the outer part of the wire, the magnetization works of the soft magnetic inner part in a single Barkhausen jump an 1800 Bloch wall is formed between the inner and the outer part of the wire, if one starts from the magnetically saturated state of the wire.

If the polarity of the switch panel is then reversed, then with a very specific one The same size of the soft magnetic inner part of the wire suddenly again magnetized and the 1800 Bloch wall driven out of the material. Disadvantageous affects the switching core described above, which also z. B. in "Electronics" 1980 Issue 7, pages 43 to 47 and 50 as a magnetic sensor to indicate presence of a magnetic field is described by the emission of pulses, from that one essentially only has wire-shaped bodies available and is based on chemically homogeneous material is restricted to a certain alloy system. These wires also need a are subjected to extremely complex and cumbersome pulling and twisting treatment, being of a defined, fine grain structure to ensure the required Ductility has to be assumed, at the end of which a combination of hard magnetic outer Part and soft magnetic inner part.

There are already magnetic toroidal cores from one chemical and magnetic uniform material, such as B. made of ferrite, has been proposed as switching cores.

Furthermore, magnetic toroidal cores are known in which the radial inside parts switch for smaller fields than the outside ones. Of the However, the switching mechanism described can only be generated with toroidal cores, not- on the other hand, in the case of switching skills with an elongated shape, which has a completely different geometry own.

It is therefore an object of the present invention to provide a magnetic To create switching core that does not have the disadvantages mentioned and the related the design and the switching processes expanded and optimized application possibilities offers.

The task is accomplished by an elongated magnetic switch core solved with at least two areas touching each other, the areas of each consist of materials with different compositions, of which at least one is magnetizable, i.e. ferromagnetic, with the areas undetachable are joined together in a common composite body.

This composite body, which is produced by joining processes such as casting, extrusion, Forging, drawing, plating, shrinking and / or gluing from various material components is produced, opens up a far greater possibility in terms of shape of the magnetic switch core. The composite body can, for. B. as a wire-shaped single core body be designed, the one material as a wire core and the other material as a coaxial jacket, or z. B. as a wire-shaped core with two coaxial Coats consist of different materials.

Furthermore, the switch core can also be designed as a multi-core body be, with a bundle of wires in a sheath made of a material component Finally, it is made of at least two different materials the wires enclosed by a jacket can have a different cross-section have and a central wire core with a larger diameter made of a material and surrounding wires with a smaller diameter made of a different material exist.

However, you are not tied to the wire shape.

According to a further embodiment of the invention are namely also “Sandwich-like”, flat multi-layer body with at least two layers possible, which consist of at least two different materials. So can the axial one required for the sudden switching of the magnetic switch core preferred magnetic direction of the soft magnetic material in contrast to that hitherto known from the prior art switching core with a variety of different Methods are obtained.

So z. B. a soft magnetic textured material can be used, whereby with non-vanishing crystal anisotropy a very specific direction of magnetization Is also favored by a subsequently introduced anisotropy, e.g. by a magnetic field annealing below the Curie temperature can be determined by the material Emboss a preferred magnetic direction as you wish.

Furthermore, the different magnetostriction depending on the material can be used to produce a certain preferred magnetic direction.

So z. B. an internal stress state by pulling the composite body realize, which is characterized by a strong compressive stress component Bei Present negative magnetostriction of the soft magnetic material in the longitudinal direction a preferred magnetic direction is then established in this.

By installing an additional non-magnetic material component, which has a so-called shape memory capacity (e.g. an alloy of 50 atom% Nickel and titanium, which are described in DE-AS 1288 363 and DE-PS 15 58 715, for example will), can a certain state of stress through heat treatment can be set. Depending on the sign of the magnetostriction, it can pass Train resp.

Compressive stresses the desired axial magnetic preferential direction to adjust. In addition, this state of stress is due to the effect of temperature controllable, which opens up the possibility of the actual function of the magnetic Switch core on or off at a certain temperature.

Different coefficients of thermal expansion can also be used utilize the individual material components to create suitable stress states and thus realizing preferred directions.

Namely, the magnetically softer component has z. B. a smaller one linear thermal expansion coefficient than the other component (s) and if a corresponding final heat treatment is carried out, then remains after cooling the soft magnetic component under compressive stress, which is negative Magnetostriction in the longitudinal direction to a preferred axial magnetic direction the soft magnetic component leads. With positive magnetostriction in the longitudinal direction would have to achieve the same effect, a soft magnetic material with a larger linear thermal expansion coefficients can be selected. The non-magnetic respectively.

non-magnetizable areas made of an alloy with shape memory (so-called memory alloy) or made of an alloy with to the magnetizable resp. magnetic alloy of the neighboring area with different thermal expansion coefficients are therefore used to identify certain voltage states and thus magnetic Set preferred directions in the neighboring areas.

However, it is also possible to use switching cores, the areas made of at least two magnetizable materials with different coercive field strengths own. This results in expanded possibilities with regard to the combination different materials, with which the properties of the magnetic switch core changed in many ways and thus adapted to the respective application can be. With such magnetic switching cores several Circuits take place.

Such magnetic multiple switching cores are suitable, for. B. for acquisition several different threshold values of external magnetic fields and so for detection of discrete field strength ranges.

Leave the cross-sectional ratios of the individual material components with single-core bodies as well as multi-core or multi-layer bodies in the Adjust principle as desired. In a preferred embodiment of a composite body a magnetically soft and a magnetically harder component become theirs Aspect ratio, however, adjusted so that it corresponds to the ratio of remanence the magnetically harder and saturation polarization of the magnetically softer component corresponds with opposing magnetization of both components an approximately equally large magnetic flux and thus largely free from stray fields State with closed magnetic field.

According to a development of the invention, the switch core receives a soft magnetic material with a preferred axial direction or it is an additional one Area made of a material with shape memory or a larger linear one thermal expansion coefficient with positive magnetostriction or a smaller one thermal expansion coefficient with negative magnetostriction in the longitudinal direction intended. Switching cores are advantageously used that have a readily deformable Permanent magnet alloy such as nickel on the one hand and an alloy on the other hand that essentially contains 45 to 55% Co, 30 to 50% Fe and 4 to 14% (Cr + V) according to one A further embodiment of the invention also includes switching cores with areas an austenitic alloy, which becomes magnetizable through deformation, is used, why z. B. on the one hand nickel and on the other hand an alloy of 16 to 19% Cr, 8 to 12% Ni, 2% Mn, 2% Si, 0.1% C and other alloy components such as e.g. B. Mo, Ti or Nb and preferably offer Fe as the remainder. According to another embodiment According to the invention, the areas with a soft magnetic material have an alloy with high electrical resistance, e.g. B. from a cobalt-nickel alloy.

The switching cores are advantageously made by joining processes such as z. B. casting, extrusion, forging, drawing, plating, shrinking and / or Gluing is inextricably joined together to form a common composite body, resulting in multi-level Heat treatments or during cold drawing at 800 to 12000C intermediate anneals and subsequent final heatings at 400 to 6000 C with a duration of 5 minutes for the intermediate glow and 10 minutes for the final glow.

Several embodiments of the elongated magnetic switch cores according to the invention are shown in FIGS. 1 to 10 and corresponding hysteresis loops in Fig. FIGS. 11 and 12 show FIG. 1 and 2 each have a cross section by a single core body, FIG. 3 to 7 cross-sections through multi-core bodies of different types Arrangement, FIGS. 8 to 10 cross sections through multilayer bodies constructed like a sandwich, Figure 11 shows a typical hysteresis loop from a single switching magnetic Switch core according to the invention and FIG. 12 shows a typical hysteresis loop of one multi-switching magnetic switch core according to the invention.

Which arrangement should be chosen expediently depends on various Points of view, z. B.

the different deformability of the different materials, which are selected for switching effects in certain fields, and availability of the various components in different semi-finished products (wire, rod, Pipe, sheet metal, etc.).

In the F i g. 1 and 2 are possible rotationally symmetrical arrangements shown by single-core bodies, as in Fig.l, the magnetically softer Material as core 1 and the magnetically harder material as jacket 2 or vice versa the magnetically softer than cladding 2 and the magnetically harder than core 1, such as in Fig. 2, can be used.

The in F i g. 3 shown cross section of a multi-shell, concentric Arrangement with 3 different materials 3, 4 and 5 represents a magnetic switch core represents, with which two circuits triggered one after the other at different field strengths can be.

The multi-core body assemblies shown in Figs. 4 to 6 have the advantage that the Aspect ratios of the two wire-shaped components 6 and 7 or 9, 10 and 11 can be changed in a simple manner can without changing the dimensions of the initial state, what an 'economical Manufacturing is of particular interest. One only needs given the total number of the wires a corresponding number of wires from the individual components 6 and 7 or 9, 10 and 11 to be used. The bundle of the individual wires is turned into a matching jacket 8 inserted This jacket can be a protective tube to fix the Be bundles or also exercise a magnetic function. The existing Gaps close when the multicore body by extrusion, forging and / or Drawing is reshaped, with simultaneous cold welding of the individual components takes place so that they can no longer shift against each other. Even With this arrangement of the core wires, multiple circuits are possible. This is based probably on the non-rotationally symmetrical structure of the switch core, which is too local different field strengths in the soft magnetic component.

Even with multi-core bodies, with a suitable structure, FIG. 6, with z. B. 3 magnetizable materials 9, 10 and 11, a double circuit - similar to with the wire according to Fig. 3 - possible. In addition, 3 and more circuits can also be used can be achieved with a corresponding number of magnetizable components.

The multicore body shown in FIG. 7 made of the materials 12 and 13 and the jacket 8 is a "combination" of that shown in FIG. 3 on the one hand and the FIGS. 4 to 6, on the other hand, show arrangements. The in the F i g. 8 to 10 The illustrated sandwich-like multilayer bodies are possible cases of more geometrical shape Arrangements when using sheet metal.

8 shows the cross section of a two-layer body made of two components 14 and 15, FIG. 9 that of a three-layer body with two or three different materials 16, 17 and 18, db. the materials 16 and 18 can be the same or different. A multilayer composite of the type shown in FIG. 10 with the components 19, 20, 21, 22 and 23 is shown, is well suited to other materials, e.g. B. those with Shape memory (memory alloys) z. B. NiTi to be installed. Hereinafter the invention is to be explained in more detail on the basis of exemplary embodiments.

Example 1 In an exemplary embodiment with an arrangement of the components According to FIG. 1, a nickel core 1 and a jacket 2 made of an alloy which essentially consisted of 51% Co, 8% V, 4% Cr, 0.5% Mn, 0.3% Si, remainder Fe, It was worked from a tube made from the above-mentioned iron-cobalt-vanadium.Chrome alloy the dimension 10 x I mm (i.e. 10 mm outer diameter, 1 mm wall thickness) assumed, into which a nickel rod with a diameter of 8 mm was drawn. This composite body was drawn to a diameter of 0.25 mm, with only one annealing of 5 minutes duration at 10000C with a diameter of 2 mm was switched on. It was finally annealed at 5000C for 10 minutes. Then a 100 mm long sample the hysteresis loop shown in Fig. lot with slow field change, d. H.

quasi-static, measured. The measuring coil had a length of 50 mm and carried 5000 turns. From Fig. 11 it can be seen that when driving through symmetrically of the hysteresis loop (points a to X a) polarization jumps / 1ffi1 or AJ2 from around 0.1 T occur with a jump field strength of around 1.5 kA / m. With asymmetrical Run through the hysteresis loop depending on the position of the reversal point (c - -. d) Polarization jumps Af3 Af4 up to -445T with jump field strengths up to about 2.5 kA / m on. At 50 Hz operation were using a coil with 4000 turns Voltage pulses with amplitudes of up to 3 V and typical half-widths of 20 ps measured.

Example 2 In a further exemplary embodiment with an arrangement the components according to FIG. I was worked with the same materials and from the same dimensions assumed as in Example 1. The composite body was at 2 mm diameter annealed for 5 minutes at 10000C and then to a diameter cold drawn from 0.5 mm. On a 100 mm long. A sample of this wire was taken from a dynamic measurement with 50 Hz received a pulse of 25 V The measuring coil had a Length of 50 mm and carried 4000 turns. From this example it can be seen that for the magnetic switch core according to the invention neither a specific wire diameter a final annealing is absolutely necessary.

Example 3 An iron-cobalt-vanadium-chromium alloy tube the dimensions 55 x 5 mm and a length of 120 mm was at one end with a 5mm thick plate (material St37) closed. A nickel cylinder was placed in this pot fitted so that a structure as in Fig. 1 was again. The composite was Formed at 12000C by means of an extrusion press into a rod with a diameter of 20 mm After cleaning the rod and removing the end pieces, it was adjusted to a diameter of 0.25 mm cold-drawn, with only two anneals lasting 5 minutes 10000C were switched on for diameters of 8 and 2 mm, and 10 minutes for Annealed 500 ° C. The magnetic and momentum measurements were similar to those in Example 1.

Example 4 For the production of a device according to FIG. 5 built magnetic 13 wires 6 made of Ni and 6 wires 7 from the one mentioned in Example 1 were used as the switching core Alloy with diameters of 2 mm used.

These were in a protective tube 8 made of a copper-nickel alloy with 70% copper of the dimensions 12 x 1 mm inserted. This composite was with the inclusion of an annealing treatment at a diameter of 2 mm to a diameter 0.25 mm drawn and then annealed at 5000 C. The magnetic properties shows Fig. ins On the symmetrical loop (points a to g, a) step 4 twice Polarization jumps Aji to Af8 of about 0.1 T each with jump field strengths between 1.5 and 3.5 kA / m on In asymmetrical operation, depending on the position of the Reversal point (c, d or e) on the returning part of the curve one, two or more Polarization jumps 419 to all5 with jump heights of up to 0.25 T.

Example 5 In a further exemplary embodiment with an arrangement the components according to FIG. 1 was made with a nickel core 1 and a cladding 2 made of V2A. Dimensions and processing correspond to those of example 1, whereby only the tempering treatment at 5000C was omitted. The magnetic measurements showed, similarly to Example 1 (FIG. 11), two polarization jumps with symmetrical excitation JJI and Af2 of around 0.1 T at around 1.5 kA / m and polarization jumps in the case of asymmetrical excitation on the returning part up to 0.5 T with jump field strengths between 1.5 and 2 came. Thereby voltage pulses with an amplitude up to 1.5 V and a typical Half width of 20 ns obtained.

Example 6 A tube made of nickel measuring 55 x 12 mm and one Length of 120 mm was fixed at one end with a 5 mm thick plate (material St 37) locked.

A cylinder made of an iron-cobalt-vanadium # chromium alloy was placed in this pot fitted so that again a structure as in FIG. 1 was created. The further processing was carried out according to Example 2. In the case of symmetrical and asymmetrical modes of operation, Polarization jumps of around 0.1 T with jump field strengths of 0.5 to 1.0 kA / m are obtained.

Instead of the permanent magnet materials used in the exemplary embodiments On the basis of iron-cobalt-vanadium-chromium, other malleable materials can also be successfully used Magnetic materials are used, z. B.

Chromium-iron-cobalt or iron-molybdenum-nickel alloys. With chrome-iron-cobalt alloys in the composition range 20 to 35% Cr, 4 to 20% Co, the remainder Fe can be passed through Variation of the composition and the heat treatment the magnetic values (remanence and coercive field strength) within wide limits. This is the possibility given, the jump field strength of the elongated magnetic switching cores to the respective Adapt application cases in a targeted manner.

Instead of the soft magnetic component in the exemplary embodiments Nickel used can be other soft magnetic materials with axial magnetic Preferred direction can be used, e.g. texture materials made of Fe-Ni, Fe-Co, Bi-Co or Fe-Ni-Co alloys.

Claims (22)

Claims: 1. Elongated magnetic switch core, the has at least two mutually contacting areas, and the one in an outer one Magnetic field abruptly when exceeding or falling below a certain field strength reverses its direction of magnetization, characterized in that the areas each consist of materials with different compositions of which at least one is magnetizable and the non-detachable to a common composite body are joined together. 2. Switching core according to claim 1, characterized in that it forms a wire-shaped single-core body that has one material as the wire core (1) and the other material as a coaxial jacket (2) (Figs. 1 and 2). 3. Switching core according to claim 2, characterized in that it a wire core (5) and two coaxial jackets (3, 4) each made of different Having materials (Fig. 3). 4. Switching core according to claim 1, characterized in that it has a Forms multi-core body, which consists of a bundle of wires (6, 7, 9 to 11) from at least consists of two different materials in a common jacket (8) (F i 4 to 6). 5. switch core according to claim 4, characterized in that this has a wire core (13) with a larger diameter made of a material which of several wires (12) with a smaller diameter made of a different material and the jacket (8) is surrounded (Fig. 7). 6't # ch <## tkern according to claim 1, characterized in that this forms a flat multi-layer body with at least two layers made up of at least two different materials (14 to 23) exist (Fig. 8 to 10). 7. switch core according to claims 1 to 6, characterized in that the areas of at least two magnetizable materials with different coercive field strengths exhibit. 8. switch core according to claim 7, characterized in that the product from the cross-section and the saturation polarization of the magnetically softer material roughly equal to the product of the cross section and the remanence of the magnetically harder one Material is 9. Switching core according to one of claims 1 to 8, characterized in that that this contains a soft magnetic material with a preferred axial direction 10. Switching core according to claim 9, characterized in that for generating the axial Preference device an additional area made of a material with shape memory (»Memory alloy«) is provided 11. Switching core according to claim 9, characterized in that that the soft magnetic material has a positive magnetostriction in the longitudinal direction and a greater coefficient of linear thermal expansion than the heavier or non-magnetizable materials. 12. Switching core according to claim 9, characterized in that the soft magnetic Material has a negative magnetostriction in the longitudinal direction and a smaller linear one thermal expansion coefficient than the more difficult or non-magnetizable Has materials. 13. Switching core according to claim 7, characterized in that this contains an easily deformable permanent magnet alloy. 14. Switching core according to claim 13, characterized in that it consists on the one hand of nickel and on the other hand of an alloy which essentially Contains 45 to 55% Co, 30 to 50% Fe and 4 to 14% (Cr + V). 15. Switching core according to claim 7, characterized in that it contains an austenitic alloy, which becomes magnetizable by deformation 16. Switching core according to one of Claims 1 to 13 or 15, characterized in that This, as a soft magnetic material, is an alloy with high electrical resistance contains. 17. Switching core according to claims 1 to 13 or 15, characterized in that that this contains a cobalt-nickel alloy as a soft magnetic material 18. Switching core according to claim 15, characterized in that it consists on the one hand Nickel and, on the other hand, an alloy consisting essentially of 16 to 19% Cr, 8 to 12% Ni, 2% Mn, 2% Si, 0.1% C and other alloy components such as z. B. Mo, Ti or Nb, and the remainder Fe. 19. A method for producing a switch core according to one of the claims 1 to 18, characterized in that the different forming the switching core Materials by joining processes, such as B. by casting, extrusion, forging, Pulling, plating, shrinking and / or gluing, inextricably linked to one another Composite bodies are joined together. 20. The method according to claim 19, characterized in that the by Composite bodies created by joining processes are subjected to a multi-stage heat treatment will. 21. The method according to claim 20, characterized in that the composite body intermediate annealing during cold drawing at 800 to 12000C and then a final annealing at 400 to 6000C. 22. The method according to claim 21, characterized in that the composite body an intermediate anneal of approx. 5 minutes and a final anneal of approx. 10 Minutes duration.