DE102019135634A1 - DEVICES AND METHOD FOR FORMING ALIGNED MAGNETIC CORES - Google Patents

Abstract

The disclosure provides devices and methods for forming aligned magnetic cores. Magnetic cores and methods and apparatus for forming the same are disclosed. The magnetic core may include a magnetic body with magnetic grains and a magnetic flux path, the magnetic grains being oriented in a variety of different directional orientations to match the magnetic flux path. The grain orientation of the cores can be provided by devices including electrical circuitry and / or permanent magnets. The devices may be configured to generate magnetic fields that approach, mimic, or mimic a magnetic flux path in the magnetic core once solidified and in use. The magnetic fields can align the grains of the magnetic core when in an unconsolidated state so that the grains are aligned in a variety of directed orientations that approach, mimick, or correspond to a magnetic flux path in the magnetic core.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a partial continuation of U.S. Patent Serial No. 15 / 962,268, filed April 25, 2018, which is a division of U.S. Application Serial No. 14 / 535,807, filed November 7, 2014 , the disclosures of which are hereby incorporated in full by reference into the present document.

TECHNICAL AREA

The present disclosure relates to aligned magnetic cores and devices, and methods of making the same.

GENERAL PRIOR ART

Electrical machines convert energy through electromagnetic interactions, e.g. B. Electricity in electricity (transformer), electricity in mechanical power (motor) or mechanical power in electricity (generator). One factor that affects energy conversion is the magnetic core materials, which usually consist of layers of electrical steel (also called silicon steel). In addition to electrical machines, magnetic cores in inductors also play a role in their performance. A core loss (also called iron loss) in the magnetic core, however, occurs due to the AC magnetic field within the materials, especially during high-frequency operation. Core loss generally has three components: hysteresis loss, eddy current loss, and over-loss (or abnormal loss). The hysteresis loss is frequency independent, whereas both the eddy current loss and the excess loss are frequency dependent.

Since fuel consumption in electric vehicles (EV), such as hybrid electric vehicles (HEV), is an important factor, plug-in hybrid EV (PHEV) and battery EV (BEV) can reduce core loss and reduce induction (flux density ) in the magnetic cores (such as rotor and stator cores) of electrical machines and power electronics (such as inductor cores). Conventional nucleation techniques generally reduce losses by sacrificing other magnetic properties or improving magnetic properties such as flux density, but sacrificing power loss.

A common way to reduce core loss in a magnetic core is to reduce the sheet thickness of the electrical steel by mechanical rolling, including hot and cold rolling. Magnetic cores with thinner layers are characterized by a significantly lower eddy current loss and therefore by a lower core loss than thicker layers. Another way to reduce core loss is to reduce the chemical composition in electrical steels, e.g. B. to control the Si and Al content. Since Si and Al increase resistivity in electrical steels, they are generally controlled during manufacture to reduce eddy current loss. Mostly 2-3% Si is used in non-aligned electrical steel and about 6% in grain-oriented electrical steel. Although the core loss is significantly reduced by these two approaches, it can still be problematic, particularly in high frequency applications. Another approach to reducing core loss is to manufacture magnetic powders that are sintered into a core directly with or without an insulating coating on the magnetic particles. A similar approach is to mix magnetic powder with a binder and then press it into near-contour devices. However, the use of a binder can reduce the flux density and permeability of the core.

SUMMARY

In at least one embodiment, a magnetic core is provided which comprises a magnetic body with magnetic grains and a magnetic flux path, the magnetic grains being aligned in a large number of different directional orientations in order to match the magnetic flux path. Each orientation can be a primary orientation with respect to the magnetic body. In one embodiment, the magnetic body has an internal cavity. The plurality of directional orientations can extend around a circumference of the inner cavity.

In one embodiment, the magnetic core is an inductor core. In another embodiment, the magnetic core is a stator core with a plurality of stator teeth and a plurality of stator slots between the stator teeth. The plurality of directional orientations may include a plurality of arcuate orientations from one stator tooth to another stator tooth around a stator slot. In another embodiment, the magnetic core is a rotor core with a plurality of permanent magnets arranged therein. The plurality of directional orientations may include a plurality of orientations that extend between the permanent magnets and an outer periphery of the rotor core.

In at least one embodiment, a holder for aligning grains in a magnetic core is provided. The device may include one or more internal magnets configured to be located inside the core, the internal magnets configured to generate a magnetic field in the magnetic core and align the grains in a variety of directional orientations.

The internal magnets can be configured to generate a magnetic field in the magnetic core that mimics a magnetic flux path of the magnetic core. Each inner magnet can have a north side (N) and a south side (S). The device may include a plurality of inner magnets and a plurality of outer magnets configured to be external to the core, and each inner magnet may pair with an outer magnet. For each pair of magnets, either the north or south sides can face each other and adjacent pairs of magnets can be configured so that the north and south sides are opposite each other.

In one embodiment, the magnetic core is a stator core with a plurality of stator teeth and a plurality of stator slots between the stator teeth. The inner magnets can be configured to create a magnetic field in the stator core and to align the grains in a variety of arcuate orientations from one stator tooth to another stator tooth around a stator slot. The internal magnets can be configured to be at the tips of the stator teeth or in the stator slots. In another embodiment, the magnetic core is a rotor core and the inner magnets are rotor permanent magnets which remain in the rotor core after being brought together.

In at least one embodiment, a device for aligning grains in a magnetic core is provided. The device may include one or more inner wires configured to be located inside the core and conduct electrical current in a first direction, and one or more outer wires configured to be outside the core and conduct electrical current in a second direction opposite to the first direction. The inner and outer wires can be configured to generate a magnetic field in the magnetic core.

In one embodiment, the inner and outer wires are configured to generate a magnetic field in the magnetic core and to align the grains in a variety of directional orientations that mimic a magnetic flux path of the magnetic core. The device may include a plurality of inner wires and a plurality of outer wires, and each inner wire may pair with an outer wire.

Figure list

• 1 10 is a flowchart for a method of forming a sintered magnetic core according to an embodiment;
• 2nd 10 is a flowchart for a method of forming a bonded magnetic core in accordance with an embodiment;
• 3rd Fig. 3 is a schematic illustration of a rectangular inductor core with a flow direction along its circumference;
• 4th FIG. 4 is a schematic illustration of an apparatus for applying a magnetic field to a rectangular inductor core using one or more electrical circuits in accordance with an embodiment;
• 5 FIG. 4 is a schematic illustration of an apparatus for applying a magnetic field to a cylindrical inductor core using one or more electrical circuits in accordance with an embodiment;
• 6 FIG. 3 is a schematic illustration of an apparatus for applying a magnetic field to a rectangular inductor core using a plurality of permanent magnets according to an embodiment;
• 7 is a finite element analysis simulation of the magnetic field 6 ;
• 8th is a schematic representation of an apparatus for applying a magnetic field to a cylindrical inductor core using a plurality of permanent magnets according to an embodiment;
• 9 FIG. 14 is a schematic illustration of an apparatus for applying a magnetic field to a rectangular inductor core using a plurality of permanent magnets and iron cores according to an embodiment;
• 10 is a curve of the magnetization over the field strength in an aligned magnetic core compared to an isotropic magnetic core;
• 11 is a schematic representation of an apparatus for applying a Magnetic field to a stator core using one or more electrical circuits according to an embodiment;
• 12th FIG. 4 is a schematic illustration of another device for applying a magnetic field to a stator core using one or more electrical circuits according to an embodiment;
• 13 is a schematic representation of an apparatus for applying a magnetic field to a stator core using a plurality of permanent magnets according to an embodiment;
• 14 FIG. 4 is a schematic illustration of another device for applying a magnetic field to a stator core using a plurality of permanent magnets according to an embodiment;
• 15 is a schematic representation of an apparatus for applying a magnetic field to a rotor core using a plurality of permanent magnets according to an embodiment;

DETAILED DESCRIPTION

Detailed embodiments of the present invention are disclosed in the present specification as prescribed; however, it is to be understood that the disclosed embodiments are purely exemplary of the invention, which can be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be enlarged or reduced to show details of certain components. Accordingly, the specific structural and functional details disclosed in the present specification should not be interpreted as restrictive, but merely as a representative basis in order to teach the person skilled in the art the various uses of the present invention.

As described in the background, conventional magnetic core processing generally requires a choice between good magnetic properties and good loss behavior (i.e., low loss). The present disclosure provides methods and devices for forming magnetic cores that have both good magnetic properties and little loss or degradation of a property compared to conventional magnetic cores. In at least one embodiment, magnetic cores are formed with a grain orientation along a specified predetermined or preferred direction or path. The grain alignment can be provided by applying a specific magnetic field to the magnetic core during processing. The magnetic field can be complex and / or multidirectional (e.g. not in a single straight line). The direction / orbit of the magnetic field (and the corresponding grain orientation) can correspond to or approach the magnetic flux direction that will occur in the core during use. The degree of grain alignment in the magnetic cores made by this method can be high, but can also be moderate or low, depending on factors such as the magnetic powders, the magnetic field strength, the pressing conditions, binders and others. The degree of grain alignment can be adjusted based on the required or desired properties of the magnetic cores.

The magnetic cores can be formed using any suitable method, including sintering and bonding magnetic powder. The magnetic powder can contain any magnetic material that can be sintered or bonded to produce a powder core, such as ferrite particles. The magnetic field can be applied during the formation of the cores using any suitable method, including devices with electrical circuits with one or more current-carrying wires and / or permanent magnets. The properties of magnetic cores made from any suitable magnetic material can be improved, including electrical steels (e.g., by heat treatment under magnetic fields). The disclosed magnetic cores can be suitable for numerous applications in which improved directional permeability and flux density are advantageous. For example, the disclosed magnetic cores can be used in inductors, transformers, generators, stators, rotors, or other devices that prefer better properties in certain directions.

With reference to 1 For example, in at least one embodiment, a grain-oriented magnetic core can be formed by sintering magnetic powder. The procedure 10 To form the sintered core, the magnetic powder can be produced in step 12th include. The magnetic powder, such as ferrite, silicon iron or another magnetic powder, can be produced by any suitable method.

For example, the powder can be made by pulverization, evaporation, chemical synthesis, or other techniques. In at least one embodiment, the powders are made to have a small number of grains per particle (e.g., medium or average grains per particle). In one embodiment the particles comprise up to 20 grains and in other embodiments up to 10 grains. In another embodiment, the particles comprise up to 5 grains. In another embodiment, the particles comprise 1 to 3rd Grains. In another embodiment, the particles are single crystals (e.g. a single grain). The number of grains per Particles can apply to all or substantially all of the particles in the powder or can be an average. However, it is understood that processing tolerances can result in some powders having particles with a varying number of grains. A small number of grains per particle enables easier alignment of the particles during the subsequent alignment step (s). A single grain per particle can provide the simplest alignment. The particles can be of any suitable size or diameter. In one embodiment, the particles have a size of 1 nm to 10 mm or a size in any part thereof. To provide increased densification of the magnetic core, a powder with a range of particle sizes can be used. For example, the powder may contain particles that are smaller than microns, particles that are 1-10 µm in size, particles that are hundreds of µm in size, and particles that are 1-10 mm in size.

In step 14 the powder can be mixed with an insulating material or coated with it. The high resistance of the insulating material reduces eddy current losses in the magnetic core. In one embodiment, the magnetic powder can be mixed with an insulating material, which can be any suitable dielectric or material with a high resistance. Non-limiting examples of insulating materials can be silicon dioxide, ferrite, phosphate binder, Teflon (PTFE) binder and others. Alternatively, the magnetic powder can be coated with an insulating material, so that each particle has a core / shell configuration with the magnetic material as the core and the insulating material as the shell. The magnetic powder can be coated using any suitable method, such as chemical solution, vapor deposition, sputter coating, or others. The magnetic powder can also be oxidized by a controlled oxidation process to form an insulating layer on the particles. The above isolation methods can be used individually, or any combination thereof can be used to increase the resistance of the magnetic core.

In step 16 the magnetic powder can be solidified and aligned. Conventional pressing can lead to an uneven density in the pressed body, which in turn can lead to significant changes in shape after sintering. In one embodiment, a tapping or stirring process can be used during solidification to provide more uniform compacts and to reduce or eliminate shape changes after sintering. The tapping process may include air tapping, mechanical tapping, ultrasonic tapping, or other methods of tapping or stirring the powder. In addition, any combination of the tapping processes can be performed either sequentially or simultaneously. Air tapping can include applying air pressure to the powder and / or the mold by controlling pressure, air flow, speed and time. Mechanical tapping may include tapping the powder and / or the mold using physical contact and either manual or automatic methods. Ultrasonic tapping may include tapping / vibrating the powder and / or the mold using ultrasonic waves by controlling the ultrasonic power, frequency and time.

The alignment process involves applying a magnetic field to the powder while it is in the mold (e.g. not solidified) so that the grains of the powder are aligned along the magnetic field (e.g. along their easy axes). The magnetic field can be applied in the shape or path of the direction of flow in the magnetic core, thereby increasing the permeability and flux density in the direction of flow of the finished core. Additional description of the devices and methods for generating the magnetic field is included below in the disclosure. The magnetic field can be applied while a knock is being performed. The tapping / stirring generated during the tapping process allows the magnetic powder to rotate and align more easily, so that the easy axes are aligned with the magnetic field. If, as described above, the particles have a single or only a plurality of grains per particle, the alignment in the magnetic field is also further facilitated. To further facilitate and promote the rotation of the magnetic particles during the alignment process, a lubricant can be added to the powder during this step. Non-limiting examples of suitable lubricants can be surfactants, calcium stearate, polyethylene glycols, sorbitol, glycerol monostearate or others as well as mixtures thereof.

In step 18th an optional pressing process can be carried out. Any suitable pressing process can be used to increase the density of the magnetic core, such as uniaxial pressing. During the pressing step 18th a magnetic field can be applied to keep the particles in shape or to align them further. The magnetic field can be the same as that in step 16 was created. As a result of the knocking process in step 16 the compact resulting from the pressing may have a substantially uniform density.

In step 20 the magnetic powder can be sintered to solidify the powder and form a finished magnetic core. The sintering temperature can be any suitable temperature to solidify the powder, for example from 600 ° C to 1,500 ° C. The sintering time can be any suitable time to solidify the powder, for example 10 minutes to several hours. In general, higher temperatures require shorter sintering times and vice versa. During the sintering step 20 a magnetic field can be applied to keep the particles in shape or to align them further. The magnetic field can be the same as that in the steps 16 and or 18th was created. As a result of the knocking process in step 16 the compact resulting from the pressing may have a substantially uniform density. After sintering, a finished magnetic core is formed with aligned grains with increased permeability and flux density along the path of the aligned grains, which were formed using a predetermined, matched magnetic field, which occurs during the solidification step 16 and optionally the pressing step 18th and / or sintering step 20 was created.

Furthermore, in some embodiments, magnetic powder (or solid samples) can be heated while an external magnetic field is applied prior to sintering. In one or more embodiments in which a magnetic field is applied during the heating step, the magnetic field may be an external magnetic field. The powder can be tapped while the external magnetic field is applied, as in the tapping procedure from step 16 to further align the magnetic powder. In at least one embodiment, an electrical current is applied to the magnetic powder after it is aligned and dense to generate heat (ie, Joule heating). In at least one embodiment, the electrical current is about 5 to 150 A, in other embodiments, about 10 to 125 A, and in still other embodiments, about 15 to 100 A. In some embodiments, the electrical current heats a container to generate heat in the magnetic powder . The container can be used as a heating medium during the tempering step. The container can be any suitable conductive material, such as graphite, among others. In certain embodiments, at least the bottom of the container includes insulating materials, such as ceramic, among others. In other embodiments, the bottom and lid of the container are conductive while the side of the container is an insulating material. In another embodiment, the magnetic powder can be heated by placing the powder assembly in a coil that carries a high frequency electrical current (ie, induction heating). In at least one embodiment, the high frequency is about 5 to 500 kHz, in other embodiments about 10 to 450 kHz and in still other embodiments about 15 to 400 kHz. In certain embodiments, the current is approximately 5 to 150 A, in other embodiments approximately 10 to 125 A and in still other embodiments approximately 15 to 100 A. An alternating magnetic field creates an eddy current in the magnetic powder assembly due to the high frequency current in the coil, which in turn Heat is generated in the magnetic powder assembly. In some embodiments, to maintain magnetic powder alignment, a DC component can be added to the current in the coil.

The heat generated melts the rarely rich grain boundary phase, similar to a sintering furnace, to form the soft magnetic core. The external magnetic field can be applied until the magnetic powder temperature reaches the Curie temperature of the main phase of the magnetic powder to ensure that the magnetic particles are aligned after sintering. The Curie temperature may or may not be higher than the melting point of the boundary phase of the main phase of the magnetic powder. The powder assembly can be a soft ferrite, pure iron, iron silicon or other suitable soft magnetic core materials. However, as an example of materials with Curie temperatures with regard to melting points, rare earth examples are discussed in the present document (e.g. neodymium magnets, in which the Curie temperature of Nd ₂ Fe ₁₄ B is lower than the melting point of the less frequently rich phase) . In some embodiments, the Curie temperature is higher than the melting point of the boundary phase. For example, in SmCo magnets, the Curie temperature of SmCo is higher than the melting point of the rarely rich grain boundary phase. As such, in the SmCo magnet example, the external field is maintained at a temperature higher than the SmCo phase, about 800 ° C. After the magnetic powders have reached the Curie temperature of the main phase, the magnetic powders become paramagnetic and the self-demagnetizing force is eliminated. Therefore, the external magnetic field can be removed to reduce energy consumption. For example, the external magnetic field does not have to be applied during sintering as in other embodiments.

The sintering step 20 In some embodiments, after heating with an external magnetic field, it may be performed at a heating temperature that is higher than the melting point of the less frequently rich phase. The melting point can be, for example, about 500 to 900 ° C. The sintering step melts the rarely rich phase around the grain boundaries so that the powders stick together to form a solid compact. As the sintering temperature continues to increase, the density of the compact increases and the grains begin to grow. The grain size can be optimized by selecting the time and temperature during sintering to achieve the desired magnetic properties in the to achieve finished magnets. After sintering, the magnets are cooled and have an improved orientation because the magnetic powder can be heated while being exposed to an external magnetic field.

With reference to 2nd For example, in at least one embodiment, a grain-oriented magnetic core can be formed by bonding magnetic powder. The procedure 30th to form the bonded core can manufacture the magnetic powder in step 32 include. The magnetic powder can be used in a similar manner to that described above with reference to step 12th described, manufactured. In step 34 the magnetic powder can be mixed with a lubricant and / or an insulating material. The insulating material and the lubricant can be the same with reference to step 14 described be similar. Accordingly, the steps 32 and 34 not described again in detail.

To make a bonded core instead of a sintered core, a binder can be used to solidify and secure the magnetic powder (and any insulating material or lubricant that is present). Any suitable binder can be used, such as thermosets, thermoplastics, elastomers, inorganic ceramic binders, high temperature ceramic binders, or others. A non-limiting example of a thermoset that can be used as a binder is an epoxy, which can be phenol or novalac. A non-limiting example of a thermoplastic that can be used as a binder is a polyamide, such as polyphenylene sulfide (PPS). Non-limiting examples of elastomers that can be used as binders include nitrile rubber, polyethylene rubber and vinyl rubber.

In step 36 the magnetic powder can be aligned using a magnetic field. The mixture of magnetic powder and binder (plus any lubricant or insulating material) can be placed in a mold while the binder is in a liquid or uncured state (e.g., not solidified). While the binder is in the liquid or uncured state, a magnetic field can be applied to the mixture and / or the mold to align the magnetic particles in a preferred pattern or direction. Because the binder has not yet cured, the magnetic field makes it easier for the particles to align because they can rotate freely, which can allow the magnetic powder to align more easily with its light axes aligned / parallel to the magnetic field . As described above, the rotation can be further facilitated by using particles with one or a few grains. The magnetic field can be applied in the shape or path of the direction of flow in the magnetic core, thereby increasing the permeability and flux density in the direction of flow of the finished core. Additional description of the devices and methods for generating the magnetic field is included below in the disclosure. Although not required, a tapping process similar to that in step can be performed during the alignment process 16 described can be applied to the binder and powder mixture.

In step 38 an optional pressing process can be carried out. Any suitable pressing process can be used to increase the density of the magnetic core, such as compaction (e.g. uniaxial pressing), extrusion or injection molding. In one embodiment, the binder used can be a thermoset when compaction is performed. In another embodiment, the binder during extrusion can be an elastomer or a thermoplastic. In another embodiment, the binder during injection molding can be a thermoplastic. During the pressing step 38 a magnetic field can be applied to keep the particles in shape or to align them further. The magnetic field can be the same as that in step 36 was created.

In step 40 the mixture of magnetic powder and binder can be hardened. The curing time and temperature can vary depending on the type of binder used. Some binders may not require heat and may harden at room or ambient temperature. During the hardening step 40 a magnetic field can be applied to keep the particles in shape or to align them further. The magnetic field can be the same as that in the steps 36 and or 38 was created. After curing, a finished magnetic core is formed with aligned grains with increased permeability and flux density along the path of the aligned grains, which were formed using a predetermined, matched magnetic field, which is used during the alignment step 36 and optionally the pressing step 38 and / or sintering step 40 was created.

The magnetic field applied to either the sintered or bonded magnetic cores described above can provide a magnetic core suitable for any application in which anisotropic or directional magnetic properties are desired, such as permeability, induction / flux density, coercive force, core loss, or other. Non-limiting applications from the disclosed magnetic cores can benefit from inductors, transformers, generators and rotors and / or stators from electric motors (e.g. electric vehicle motors). To provide the anisotropic / directional properties described above, a predetermined specific magnetic field can be applied while the core is being formed which corresponds to the flow path in the finished core when used in a particular application. Accordingly, the applied magnetic field can be tailored to a particular magnetic core application, such as a stator or an inductor core. By creating, mimicking, or approximating a magnetic field with a shape or one or more paths that match, mimick, or approximate the flow path (s) in the final application, permeability, flux density, and other properties can be significantly improved without increasing power dissipation affect. In the case of magnetic cores with complex shapes or with complex flux paths, the magnetic field can also be complex, for example comprising a large number of clearly curved or non-linear directional orientations.

The magnetic field can be applied using any suitable method. In at least one embodiment, an alignment device may include one or more circuits, each containing one or more wires that carry electrical current to generate the magnetic field. By controlling the arrangement or configuration of the wire (s) and the level and / or the direction of the current, a specific, user-defined magnetic field can be generated, which in operation mimics or corresponds to the direction of flow in a magnetic core. The magnetic field can therefore align the magnetic grains in a variety of directional orientations to correspond to, mimic, or follow the magnetic flux direction. In the present context, directional orientations can refer to main orientations or to those that exist on a macroscale versus a microscale. Accordingly, small deviations in the alignment from one grain to another or between several grains are not considered to be the main orientations.

In at least another embodiment, an alignment device may include one or more magnets to provide the magnetic field during the alignment process. In one embodiment, the magnets are permanent magnets. By checking the arrangement, configuration, size, shape and / or strength of the magnet (s), a specific, user-defined magnetic field can be generated that mimics or corresponds to the direction of flow in a magnetic core during operation. While the figures and the following descriptions describe devices in which electrical circuits or magnets are used to generate the magnetic field, those skilled in the art will recognize that any combination of the two approaches can also be used. In addition, each magnetic field line or direction shown or described can also be a directional alignment of magnetic grains.

With reference to the 3-15 discloses several examples of devices for generating magnetic fields for aligning magnetic grains in non-solidified inductor, stator and rotor cores. These figures and their corresponding descriptions are exemplary and, as discussed above, the disclosed methods and apparatus can be used to generate any desired magnetic field for any flow path. With reference to the 3-4 , is an inductor core 50 shown with a hollow rectangular cross section with an inner cavity. The magnetic flux 52 in the inductor core runs along the circumference of the core during operation 50 as by the arrows 54 shown. While the arrows 54 are shown clockwise, the river can 52 also be counterclockwise. The permeability and flux density in the core 50 To improve, the grains / powder of the core can be oriented towards the flow. Alignment can be provided by applying a magnetic field to the body / powder during an alignment process and optionally during a pressing process and / or sintering or curing process, as described above. A magnetic field in the shape or direction of the flow path 52 to generate, one or more electrical circuits can be configured to generate the magnetic field. The electrical circuit (s) (not shown) may have one or more live wires 56 included inside or around the inductor core 50 arranged and configured to create a magnetic field 58 in the direction or shape of the river path 52 to create.

In an embodiment shown in FIG. 4, a magnetic field 58 in the shape of the river path 52 generated by one or more wires 60 inside the inductor core 50 arranged that carry current in one direction, and one or more wires 62 outside the inductor core 50 be arranged that carry current in the opposite direction. 4th shows four wires 60 inside the inductor core 50 , however, a single wire 60 within the core 50 (e.g. in the middle) to be placed around a similar magnetic field 58 (similar to in 5 , described below). While the 3rd and 4th a device for an inductor core 50 can show with a hollow rectangular shape, the inductor core have any suitable shape, including a ring, an annular body, a rod, or others. For example, shows 5 an inductor core 50 ' with a ring shape. Similar to the rectangular core 50 in the 3rd and 4th , shows the inductor core 50 ' a river path 52 ' on that around the perimeter of the core 50 ' runs. The river path 52 ' can be clockwise or counterclockwise. To a magnetic field 58 ' in the shape or direction of the river path 52 ' can generate one or more wires 60 within the core 50 ' be arranged that carry current in one direction, and one or more wires 62 outside the inductor core 50 ' be arranged that carry current in the opposite direction. Similar to 4th , can use multiple wires 60 within the core 50 Be arranged instead of a single wire 60 , as shown. The magnetic field 58 / 58 'can cause the unconsolidated grains to orientate in a variety of directions 64 orient that to the magnetic field 58 / 58 ' correspond, imitate it or follow it. As shown, at least two or more of the alignments 64 be different from each other. Regardless of the shape of the inductor core, an electrical circuit can be designed to generate a magnetic field that corresponds to or mimics the flow path of the inductor. Similarly, the inductor core 50 be replaced by a transformer core or other magnetic core with a flux path that would benefit from aligned grains / aligned powder.

With reference to the 6-10 are additional devices for generating a specific, customer-specific magnetic field 70 for an inductor core 50 shown that has a shape or direction that the flow 52 imitates or corresponds to this. The magnetic field 70 can be generated using a device that uses a variety of magnets 72 (e.g., permanent magnets) arranged in a predetermined configuration or pattern. Every magnet 72 can have a north (N) and a south (S) configuration, and the pattern of the magnets 72 can be a magnetic field 70 generate that the flow path 52 imitates, corresponds to or approaches this and accordingly aligns the grains along this. In the in 6 embodiment shown are four magnets 72 inside the inductor core 50 arranged and four magnets are outside the core 50 arranged. A magnet is on the inside and outside of each of the four sides of the core 50 arranged. The magnets 72 can be arranged in such a way that the N and S sides / sections of the magnet to the inductor core alternate inside and outside 50 demonstrate. In 6 are magnets with the inductor core 50 pointing / pointing N-side / section with 74 and magnets with to the inductor core 50 pointing / pointing S-side / section are with 76 designated. The magnets 72 can be arranged so that magnets 74 , whose N side faces the inductor, face each other, and magnets 76 , whose S-side faces the inductor, face each other. As in 6 shown, this configuration creates a magnetic field 70 with a shape that matches the circumference of the inductor core 50 follows. The magnetic field 70 can compared to the magnetic field 58 in 4th do not form a complete loop; however, the orientation of the granules / powder is similar. A finite element analysis simulation (FEA simulation) of the in 6 magnet arrangement shown is in 7 shown. The FEA simulation shows that the magnetic field 70 the scope of the core 50 follows, with slight interruptions at points where the magnets are located (e.g. forming an almost complete loop). The magnetic field 70 can cause the unconsolidated grains to have a variety of directional orientations 78 orient that to the magnetic field 70 correspond, imitate it or follow it. As shown, at least two or more of the alignments 78 be different from each other.

As above with reference to 5 described, the inductor or transformer core can have any suitable shape, such as a ring, an annular body or a rod. As in 8th shown, can also use a variety of magnets 72 be arranged to a desired magnetic field 70 ' to produce in other core forms. Similar to that with reference to 6 described arrangement, can be a variety of magnets 72 inside and outside the core 50 ' be arranged. The magnets 72 can be arranged in such a way that the N and S sides / sections of the magnet to the inductor core alternate inside and outside 50 demonstrate. The magnets 72 can be arranged so that magnets 74 , whose N side faces the inductor, face each other, and magnets 76 , whose S-side faces the inductor, face each other. As in 8th shown, this configuration creates a magnetic field 70 with a shape that matches the circumference of the inductor core 50 follows.

During the arrangement of the magnets 72 in the 6 and 8th four magnets inside and four magnets outside with a pair of magnets on each side, such configurations are only exemplary and are not intended to be limiting. The number and / or position of the magnets 72 can be adjusted to tailor the magnetic field to the desired shape / direction. For example, more magnets 72 can be used to provide a more uniform, complex and / or sophisticated magnetic field. In the in 9 Embodiment shown are eight pairs of magnets 72 in and around the core 50 With two pairs per side arranged around a magnetic field 70 " to provide. The field 70 " can have a shape similar to the magnetic field 70 have that by the arrangement of four pairs of magnets 72 is generated which in 6 are shown, however, the increased number of magnets 72 provide a more controlled and / or defined magnetic field.

In addition to adjusting the number and / or arrangement of the magnets 72 can have one or more iron cores 80 be included in the alignment device as in 9 shown. For example, an iron core 82 in the inner cavity of the inductor core 50 can be arranged and another iron core 84 outside the core 50 be arranged. The one or more iron cores can conduct the magnetic flux directions because of their much higher permeability than air. The one or more cores therefore improve the efficiency of the device and improve the magnetic alignment in the magnetic core.

With reference to 10 is a graphical representation of magnetization versus field strength in the direction parallel to grain orientation in an aligned core and in an isotropic core without grain orientation. The results clearly show that the permeability in the aligned core is significantly greater than the permeability in the non-aligned core. The values in 10 are an example and do not necessarily indicate the exact values that can be achieved using the disclosed methods and devices.

With reference to the 11-15 the disclosed methods and devices for generating a magnetic field in a magnetic core are also applicable to rotor and stator cores as well as to inductors, transformers, generators or other magnetic cores. An attachment for an external or external stator core 100 is in 11 shown, the core 100 Stator teeth 102 and stator slots or columns 104 contains. The magnetic flux in a stator core 100 during operation, generally includes multiple flow paths, the arches of a stator tooth 102 around a stator slot 104 to another stator tooth 102 form. Accordingly, a magnetic field can be used to increase the permeability and flux density along the flow paths 106 generated that mimics or approaches the flow paths and aligns the grains along them.

In one in 11 shown embodiment can the magnetic field 106 generated using a device that includes one or more electrical circuits. The electrical circuitry (not shown) can be one or more live wires 108 contain. One or more wires 110 can inside the stator slots 104 be arranged, and one or more wires 112 can be outside of the stator core opposite from a wire 110 inside a stator slot 104 be arranged. Accordingly, the device may include one or more pairs of wires, with one wire in each pair within the stator (e.g., in a slot 104 ) and one from each pair outside the stator core 100 lies. In one embodiment, a wire 114 conduct current in one direction in each pair while the other wire 116 carries current in the opposite direction in each pair. The pairs of wires can alternate their configuration so that adjacent slots 104 Have wires with alternating current directions, as in 11 shown. As a result of the alternating pairs of wires, a magnetic field can 106 generated so that arcs 118 of tooth 102 to tooth 102 around the slots 104 be formed around. This magnetic field mimics or approaches the flow paths in the stator during operation. The magnetic field 106 can cause the unconsolidated grains to have a variety of directional orientations 122 align the magnetic field 106 correspond, imitate it or follow it (e.g. arch shapes). As shown, at least two or more of the alignments 122 be different from each other.

While 11 With pairs of wires shown, one inside and one outside the stator core, in some embodiments wires are only inside or only outside the stator core 100 . For example, a device can only use wires 110 inside the stator slots 104 contain. As described above, these wires can change the current direction. While 11 shows that each stator slot 104 a wire 110 may not be in every slot in some embodiments 104 a wire may be arranged. Similar to the device for the inductor core 50 in 9 can be an iron core 120 in the device for the stator core 100 be included. A core 120 can be in the middle or in the inner cavity of the stator core 100 be included as in 11 shown. A core 120 can also use the stator 100 in addition to or instead of being located in the middle. Similar to the iron core in 9 , the iron core 120 help guide the magnetic flux to form the desired shape or pattern.

Another embodiment of an apparatus for providing alignment of a magnetic field 106 in a stator core 100 is in 12th shown. In this embodiment, one or more wires 110 ' adjacent to the stator slots 104 or the stator teeth 102 rather than inside the stator slots 104 be arranged. Arranging the wires 110 ' next to the slots 104 can be easier or more convenient with some devices. One or more wires 112 can face a wire outside the stator core 110 ' be arranged similarly as with reference to FIG 11 described. Also similar 11 , can be a wire 114 conduct current in one direction in each pair while the other wire 116 carries current in the opposite direction in each pair. The pairs of wires can alternate their configuration so that the wires 110 ' have changing current directions, as in 12th shown. As a result of the alternating pairs of wires, a magnetic field can 106 generated so that arcs 118 of tooth 102 to tooth 102 around the slots 104 be formed around. Similar to the device 11 In some embodiments, wires can only be inside or outside the stator core 100 may be present and / or not every stator tooth 102 or slot 104 a wire must be assigned.

As above with reference to the 6 , 8th and 9 described, the specific, customer-specific magnetic field can also be used using a variety of magnets 130 (e.g. permanent magnets) can be provided. The magnets 130 can be arranged in a device to the magnetic field 132 to generate a shape or pattern similar to that of the magnetic field 106 in the 11 and 12th can have. In one in 13 Embodiment shown can be a variety of magnets 130 at the tips or ends 134 every stator tooth 102 be arranged. Every magnet 130 can have an N and an S side or an N and an S section, and the magnets 130 can be arranged to have alternating N and S sections that define the stator teeth 102 are facing as in 13 shown. In other words, magnets with an N side facing the stator tooth 102 is facing with 136 , and magnets with an S-side facing the stator tooth can be marked with 138 be designated. Every magnet 136 can have a magnet on each side 138 and vice versa. As described above, an iron core 140 in the middle or in the inner cavity of the stator core 100 be arranged to carry the magnetic field 132 to support. Although not shown, the device may also include magnets located on the outside of the stator core, similar to the previously described embodiments of the inductor.

In another embodiment, the in 14 is shown, a device can be a variety of magnets 130 included in the stator slots 104 are arranged. For example, in each stator slot 104 a magnet 130 be arranged. The magnets 130 can be aligned so that the N and S sides are each one side 150 of the stator tooth 102 are facing. With some magnets 152 can face the N side clockwise and can face the S side counterclockwise while using other magnets 154 the S-side can point clockwise and the N-side counterclockwise. In one embodiment, adjacent teeth 102 have the opposite magnet configuration (e.g. 152 or 154 ) to an alternating pattern of magnets 152 and 154 to form as in 14 shown. In other words, any magnet can 152 a magnet on each side 154 and vice versa. This pattern or these magnets can create the magnetic field 132 generate as in 14 shown. As described above, an iron core 160 in the middle of the stator core 100 be arranged to carry the magnetic field 132 to support. Although not shown, the device may also include magnets located on the outside of the stator core, similar to the previously described embodiments of the inductor. The magnetic field 132 can cause the unconsolidated grains to have a variety of directional orientations 142 align the magnetic field 132 correspond, imitate it or follow it (e.g. arch shapes). As shown, at least two or more of the alignments 142 be different from each other.

With reference to 15 is a device for aligning the grains / powder of a rotor core 200 shown. The orientation of the rotor core 200 can be performed using either electrical circuitry or magnets according to the methods described above. In the in 15 The embodiment shown can be a magnetic field 202 using magnets 204 (e.g. permanent magnets). The magnets 204 can in pairs 206 grouped, which can generally form a V-shape or an angle (e.g. an obtuse angle). The magnets 204 can each have an N side and an S side or an N section and an S section. In one embodiment, each pair of magnets 206 be configured so that both magnets 204 the same side faces out (either N or S). Pairs of magnets 206 with the N side facing out can be used as 208 are referred to as couples 206 , with the S-side facing outwards, as 210 can be designated. In one embodiment, the pairs can alternate so that each pair 208 a pair on each side 210 and vice versa, as in 15 shown. While 15 four pairs of magnets 206 , two pairs of 208 and two pairs of 210 shows, the device can be any suitable number of pairs 206 from Magnets 204 contain. The magnetic field 202 can cause the unconsolidated grains to have a variety of directional orientations 212 orient that to the magnetic field 202 correspond, imitate it or follow it. As shown, at least two or more of the alignments 212 be different from each other.

In at least one embodiment, the magnets used in the device 204 be the same permanent magnets that are in their final form in the rotor core 200 are installed (e.g. in a permanent magnet motor). Accordingly, the permanent magnets that are used in the rotor also serve to align the grains / powder during the process for producing the rotor core (e.g. alignment and, if appropriate, compression and / or sintering / hardening). The permanent magnets can be embedded in the powder core during the manufacturing process and can remain in the core after finishing to form the final rotor core. Similar to the devices described above, the rotor alignment device may include an iron core 214 included the rotor core 200 surrounds (partially or completely) to guide the magnetic field 202 to support.

The non-limiting examples of in the 3-15 Devices described have been described in connection with sintered or bonded magnets. By using the devices for applying the disclosed magnetic fields while the magnetic powders are not yet fully solidified, the alignment of the grains can be simplified and made more efficient / effective. However, the disclosed devices can also be used to align solidified or fully formed magnets, such as those made from electrical steel (e.g., electrical steel sheets). In order to align the magnetic grains more effectively, the magnetic core or cores can be heated, for example to a temperature of 400 ° C to 900 ° C. Heating can be accomplished using any suitable method and the heating equipment can be added to any of the devices disclosed. Accordingly, the disclosed advantages of magnetic grain alignment described above can be implemented in magnetic cores that are not formed from magnetic powders or that have already been solidified.

Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms of the invention. Rather, the terms used in the description are descriptive rather than restrictive, and it is understood that various changes can be made without departing from the spirit and scope of the invention. Furthermore, the features of different implementing embodiments can be combined with one another to form further embodiments of the invention.

According to the present invention, a method of forming an aligned permanent magnet includes mixing or coating a rare earth magnet powder with an electrically insulating material; solidifying the powder to form a solidified powder; applying a magnetic field to the solidified powder to align its grains and form an aligned powder; and sintering the aligned powder to form the aligned permanent magnet.

According to one embodiment, the above invention is also characterized by pressing the aligned powder.

According to one embodiment, the solidification comprises a tapping process.

According to one embodiment, the above invention is also characterized by heating the solidified powder during application.

According to one embodiment, the heating comprises inductive heating.

In one embodiment, heating is performed until a main phase Curie temperature is reached.

According to one embodiment, the main phase Curie temperature is lower than a main phase melting point.

According to one embodiment, the solidified powder is housed in a conductive container, which also includes applying current to the conductive container.

In one embodiment, heating includes placing the solidified powder in a coil that carries electrical current to create an alternating magnetic field with an eddy current to generate heat.

According to the present invention, a method of forming an aligned permanent magnet includes solidifying a rare earth magnet powder to form a solidified powder; applying a magnetic field to the solidified powder to align its grains; during application, heating the solidified powder to a main phase Curie temperature of the rare earth magnet powder to form an aligned powder; and sintering the aligned powder to form the aligned permanent magnet.

According to one embodiment, the solidification comprises a tapping process.

According to one embodiment, the main phase Curie temperature is lower than a main phase melting point.

According to one embodiment, the above invention is also characterized by producing the rare earth magnet powder by mixing or coating a rare earth magnet material with an electrically insulating material.

According to one embodiment, the above invention is also characterized by placing the rare earth magnet powder in a coil configured to carry a high frequency electrical current of 5 to 500 kHz.

According to one embodiment, the heating comprises generating an eddy current from an alternating magnetic field from the coil.

According to one embodiment, the rare earth magnet powder is accommodated in a container with at least one conductive surface.

According to one embodiment, at least a part of the container comprises an insulating material.

According to the present invention, a method of forming an aligned permanent magnet includes solidifying a rare earth magnet powder to form a solidified powder; applying a magnetic field to the solidified powder to align its grains; applying an electric current to heat the solidified powder to a main phase Curie temperature in the presence of the magnetic field; and after application, sintering the solidified powder to form the aligned permanent magnet.

According to one embodiment, the heating comprises placing the rare earth magnet powder in a conductive container so that the electrical current inductively heats the conductive container.

According to one embodiment, the heating comprises placing the rare earth magnetic powder in a coil and generating an alternating magnetic field from the electric current with an eddy current to generate heat.

Claims (15)

A method of forming an aligned permanent magnet comprising: Mixing or coating a rare earth magnet powder with an electrically insulating material; Solidifying the powder to form a solidified powder; Applying a magnetic field to the solidified powder to align its grains and form an aligned powder; and Sintering the aligned powder to form the aligned permanent magnet. Procedure according to Claim 1 , also comprising pressing the aligned powder. Procedure according to Claim 1 , wherein the solidification comprises a tapping process. Procedure according to Claim 1 , further comprising heating the solidified powder during application. Procedure according to Claim 4 , wherein the heating comprises inductive heating. Procedure according to Claim 4 , wherein the heating is carried out until a main phase Curie temperature is reached. Procedure according to Claim 6 , wherein the main phase Curie temperature is lower than a main phase melting point. Procedure according to Claim 4 wherein the solidified powder is housed in a conductive container, which further comprises applying current to the conductive container. Procedure according to Claim 4 , wherein the heating comprises placing the solidified powder in a coil that carries electric current to generate an alternating magnetic field with an eddy current to generate heat A method of forming an aligned permanent magnet, comprising: solidifying the rare earth magnet powder to form a solidified powder; Applying a magnetic field to the solidified powder to align its grains; during application, heating the solidified powder to a main phase Curie temperature of the rare earth magnet powder to form an aligned powder; and sintering the aligned powder to form the aligned permanent magnet. Procedure according to Claim 10 , wherein the solidification comprises a tapping process. Procedure according to Claim 10 , wherein the main phase Curie temperature is lower than a main phase melting point. Procedure according to Claim 10 , further comprising producing the rare earth magnet powder by mixing or coating a rare earth magnet material with an electrically insulating material. Procedure according to Claim 10 , further comprising placing the rare earth magnet powder in a coil configured to carry a high frequency electrical current of 5 to 500 kHz Procedure according to Claim 14 wherein the heating comprises generating an eddy current from an alternating magnetic field from the coil.

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