Bonded neodymium-iron-boron magnet ring structure with demagnetization resistance and magnetizing method of bonded neodymium-iron-boron magnet ring structure

Abstract

The invention relates to a bonded neodymium iron boron magnet ring structure with demagnetization resistance and a magnetizing method thereof, and belongs to the field of permanent magnet motors, the outer diameter of the magnet ring structure is circular, the inner diameter of the magnet ring structure is a changing curve, the thickness of the inner diameter at the position of a main magnetic pole is reduced, and the thickness of the inner diameter at the transition position between the main magnetic poles is increased; and the magnetic ring structure is made of a bonded neodymium iron boron material. According to the magnetic ring structure, the functional inner diameter is adopted, the demagnetization resistance of the magnetic ring under the overload condition can be improved, irreversible magnetic flux loss is reduced, and the demagnetization problem is solved. On the basis of the same outer diameter and the same height, it can be guaranteed that the consumption of the bonded neodymium-iron-boron magnet is almost equal to that of a common magnetic ring, and cost is saved.

Description

Technical Field

[0001] The present invention relates to a bonded NdFeB magnetic ring structure with anti-demagnetization capability and a magnetizing method thereof, and in particular to a bonded NdFeB annular magnet structure with anti-demagnetization capability and a matching multi-pole magnetizing method thereof, belonging to the technical field of permanent magnet motors. Background Art

[0002] Permanent magnet motors use permanent magnet materials as excitation sources. These materials have a high magnetic energy product and can provide a stable magnetic field, thereby improving the efficiency and power density of the motor. At present, the magnetic materials used in permanent magnet motors have developed to the third generation of neodymium iron boron materials. Neodymium iron boron permanent magnet materials are widely used in various power electronic products due to their excellent performance.

[0003] As a kind of third generation magnetic material, bonded NdFeB permanent magnet is made by mixing NdFeB powder with a binder and then molding. Bonded NdFeB magnet combines the magnetic properties of high-performance NdFeB materials with the flexibility of the bonding molding process. It can manufacture magnets with complex shapes through injection molding, compression molding and extrusion molding. It has the characteristics of complex shape molding, multi-pole magnetization, high precision and good mechanical properties. Among them, the magnetic ring is a typical structure of bonded NdFeB, which is particularly suitable for high-speed micro motors in the fields of electronic products, automotive industry, medical equipment and industrial automation.

[0004] Some problems have also been exposed in the application of bonded NdFeB. First, the coercive force and remanence of bonded NdFeB are lower than those of sintered NdFeB. Therefore, under the same conditions, bonded NdFeB is more prone to irreversible loss of magnetic properties, that is, demagnetization failure. The compact structural size of high-speed micro motors causes a significant temperature rise during operation. The combined effect of temperature and current can easily lead to irreversible demagnetization failure of bonded permanent magnets, thereby reducing the reliability and life of the motor.

[0005] There is currently no good solution to the above problems. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a bonded NdFeB magnetic ring structure with anti-demagnetization capability and a magnetizing method thereof, so as to overcome the problem in the prior art that the permanent magnet has insufficient magnetic property stability and is prone to demagnetization failure.

[0007] The present invention adopts the following technical solution:

[0008] A bonded NdFeB magnetic ring structure with anti-demagnetization capability, wherein the outer diameter of the magnetic ring structure is circular, and the inner diameter of the magnetic ring structure is a changing curve, wherein the inner diameter thickness at the main magnetic pole position decreases, and the inner diameter thickness at the transition position between the main magnetic poles increases;

[0009] The magnetic ring structure adopts bonded NdFeB material.

[0010] Preferably, the inner diameter of the magnetic ring structure adopts a parameterized inner diameter, and its inner diameter function satisfies: R=R2+H1cos(nθ);

[0011] Wherein, R is the inner diameter function; R2 is the circular inner diameter of the common magnetic ring; H1 is the adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the common magnetic ring; n is the number of magnetic poles, which is an even number; θ represents the angle.

[0012] In the functionalized inner diameter, the position where the magnetic ring thickness decreases is the main magnetic pole position, and the position where the magnetic ring thickness increases is the transition position between the main magnetic poles. Increasing the magnetic ring thickness in the transition zone increases the internal magnetic resistance of the permanent magnet, so that when a reverse magnetic field is applied to the permanent magnet at this position, the internal magnetic field distribution is more uniform and local demagnetization is less likely to occur.

[0013] Preferably, according to the present invention, the finite element results show that no obvious demagnetization failure will occur at the main magnetic pole position. Therefore, in the functionalized inner diameter, the thickness of the transition position is increased and the thickness of the main magnetic pole is reduced. This ensures that the amount of magnetic material used in the entire magnetic ring is consistent and reduces costs.

[0014] The inner diameter of the magnetic ring structure of the present invention adopts a functional shape to increase the anti-demagnetization ability of the easily demagnetized position and reduce the irreversible loss of magnetic flux when the motor is overloaded. The matching magnetizing fixture can position and multi-pole magnetize the anti-demagnetization magnetic ring.

[0015] Preferably, in practical applications, if the value of H1 is too small, the anti-demagnetization effect is not obvious, and if H1 is too large, the surface magnetic waveform of the magnetic ring will be distorted. The optimal value of the adjustment parameter H1 is determined by finite element simulation. The demagnetization area of ​​the permanent magnet should be controlled within a very small range to ensure the performance and stability of the motor. The optimal value of H1 is based on the new demagnetization area of ​​the permanent magnet not exceeding 2% to 5% of its surface area.

[0016] Preferably, during production, NdFeB powder is mixed with a binder to form a uniform mixture, which is then formed by injection molding, pressing or extrusion. The magnetic ring structure of the present invention can be rapidly produced in batches by designing a mold with a corresponding structure.

[0017] Preferably, the binder is, for example, epoxy resin or phenolic resin.

[0018] A magnetizing method based on the bonded NdFeB magnetic ring structure with anti-demagnetization ability, magnetizing is completed by means of a magnetizing fixture, the magnetizing fixture includes a positioning base, a magnetizing core, a winding and an upper cover, the magnetizing core is made of a silicon steel sheet lamination process, the winding is made of enameled copper wire, and the positioning base and the upper cover are made of non-magnetic materials such as nylon or aluminum alloy;

[0019] The magnetic ring structure is placed on the magnetizing core and fixed, and a magnetizing power supply is used to pass an instantaneous pulse current into the winding for magnetization. After power is cut off, the magnetic ring structure is taken out to complete the magnetization.

[0020] The multi-pole magnetizing fixture matched with the magnetic ring can perform multi-pole magnetization on the magnetic ring in radial direction. After the magnetization is completed, n magnetic poles are alternately distributed on the outer surface of the magnetic ring, and the number of magnetic poles is an even number.

[0021] Preferably, the positioning base is a circular structure, with n positioning columns A arranged around one side, and a magnetic ring positioning column B arranged in the center, and the outer contour of the magnetic ring positioning column B is the same as the inner diameter of the magnetic ring structure;

[0022] The magnetized core is a circular structure with n positioning holes arranged around it for passing the positioning column A of the positioning base, and a through hole arranged in the center for passing the magnetic ring positioning column B of the positioning base; the magnetized core is evenly provided with n winding holes around the through hole for installing the winding, and a magnetized tooth portion is formed between two adjacent winding holes. During magnetization, the magnetized tooth portion corresponds to the main magnetic pole position of the magnetic ring structure.

[0023] Preferably, the upper cover is a circular structure with n limiting holes provided thereon, and the positioning column A of the positioning base passes through the positioning hole of the magnetic core and the limiting hole of the upper cover in sequence to complete the assembly of the positioning base, the magnetic core and the upper cover.

[0024] The functionalized magnetic ring structure of the present invention requires accurate control of the magnetization position, so a positioning base of a magnetic steel is provided on the multi-pole magnetization fixture to ensure that the magnetic ring with a functionalized inner diameter can be kept fixed in the magnetization fixture according to the position, so that the main magnetic pole position of the magnetic ring is aligned with the magnetization position of the magnetization fixture, ensuring that the main magnetization position during the magnetization process is located in the middle of the magnetic pole.

[0025] For any details not provided in the present invention, please refer to the prior art.

[0026] The beneficial effects of the present invention are:

[0027] 1. The magnetic ring structure of the present invention adopts a functional inner diameter, which can improve the anti-demagnetization ability of the magnetic ring under overload conditions, reduce irreversible magnetic flux loss, and solve the demagnetization problem.

[0028] 2. The magnetic ring structure of the present invention is different from the traditional method of increasing thickness to weaken demagnetization. On the basis of the same outer diameter and the same height, the present invention can ensure that the amount of bonded NdFeB magnets consumed is almost the same as that of ordinary magnetic rings, saving costs.

[0029] 3. The multi-pole magnetizing fixture of the present invention can locate the magnetizing position of the magnetic ring to ensure that the magnetizing position matches the functionalized inner diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0031] Figure 1 A three-dimensional diagram of the bonded NdFeB magnetic ring structure with anti-demagnetization capability of the present invention;

[0032] Figure 2 It is a front view of the bonded NdFeB magnetic ring structure with anti-demagnetization capability of the present invention;

[0033] Figure 3 A schematic diagram of magnetization of a bonded NdFeB magnetic ring structure with anti-demagnetization capability of the present invention;

[0034] Figure 4 Schematic diagram of the size of the bonded NdFeB magnetic ring structure with anti-demagnetization capability of the present invention, (a) is a schematic diagram of R1 and R1, and (b) is a schematic diagram of H1;

[0035] Figure 5 It is a schematic diagram of the assembly of the magnetizing fixture of the present invention;

[0036] Figure 6 It is a schematic diagram of a magnetized core of the present invention;

[0037] Figure 7 It is a schematic diagram of the positioning base of the present invention;

[0038] Figure 8 It is a schematic diagram of the installation of the magnetizing fixture of the present invention;

[0039] Fig. 9 A winding diagram of the present invention;

[0040] Fig.10 This is the demagnetization rate distribution cloud diagram of an ordinary magnetic ring before and after demagnetization;

[0041] Fig.11 The demagnetization rate distribution cloud diagram of the magnetic ring structure of the present invention before and after demagnetization;

[0042] In the figure, 1-magnetic ring structure, 2-magnetic core, 3-winding, 4-positioning base, 5-upper cover, 11-inner diameter cut-off part, 12-inner diameter thickened part, 21-positioning hole, 22-magnetized tooth part, 41-positioning column A, 42-magnetic ring positioning column B, 231, 232, 233 and 234-winding holes. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the implementation of this specification, but are not limited to this. Anything not fully described in the present invention shall be based on the conventional technology in the art.

[0044] Example 1

[0045] A bonded NdFeB magnetic ring structure with anti-demagnetization capability, wherein the outer diameter of the magnetic ring structure 1 is circular, and the inner diameter of the magnetic ring structure is a changing curve, wherein the inner diameter thickness at the main magnetic pole position decreases, and the inner diameter thickness at the transition position between the main magnetic poles increases;

[0046] The magnetic ring structure 1 is made of bonded NdFeB material.

[0047] The inner diameter of the magnetic ring structure 1 adopts a parameterized inner diameter, and its inner diameter function satisfies: R=R2+H1cos(nθ);

[0048] Wherein, R is the inner diameter function; R2 is the circular inner diameter of the common magnetic ring; H1 is the adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the common magnetic ring; θ represents the angle; n is the number of magnetic poles, which is an even number. In this embodiment, n=4. Figure 1 As shown; Figure 4 The figure shows the schematic diagram of the magnetic pole positions of the 4-pole magnetic ring of this embodiment, wherein position 11 is the portion of the functionalized inner diameter cut off, which is the main magnetic pole position, and position 12 is the portion of the functionalized inner diameter thickened, which is the transition zone position between two adjacent magnetic poles.

[0049] In the functionalized inner diameter, the position where the magnetic ring thickness decreases is the main magnetic pole position, and the position where the magnetic ring thickness increases is the transition position between the main magnetic poles. Increasing the magnetic ring thickness in the transition zone increases the internal magnetic resistance of the permanent magnet, so that when a reverse magnetic field is applied to the permanent magnet at this position, the internal magnetic field distribution is more uniform and local demagnetization is less likely to occur.

[0050] Preferably, according to the present invention, the finite element results show that no obvious demagnetization failure will occur at the main magnetic pole position. Therefore, in the functionalized inner diameter, the thickness of the transition position is increased and the thickness of the main magnetic pole is reduced. This ensures that the amount of magnetic material used in the entire magnetic ring is consistent and reduces costs.

[0051] The inner diameter of the magnetic ring structure of the present invention adopts a functional shape to increase the anti-demagnetization ability of the easily demagnetized position and reduce the irreversible loss of magnetic flux when the motor is overloaded. The matching magnetizing fixture can position and multi-pole magnetize the anti-demagnetization magnetic ring.

[0052] like Figure 5As shown, R1 is the circular outer diameter of the ordinary magnetic ring, R2 is the circular inner diameter of the ordinary magnetic ring, H1 is the adjustment parameter, H2 is the thickness of the main magnetic pole, and H1+H2=R1-R2.

[0053] In practical applications, if the value of H1 is too small, the anti-demagnetization effect is not obvious. If H1 is too large, the surface magnetic waveform of the magnetic ring will be distorted. The parameter H1 is adjusted to determine the optimal value through finite element simulation. The demagnetization area of ​​the permanent magnet should be controlled as much as possible within a very small range to ensure the performance and stability of the motor. The optimal value of H1 is based on the new demagnetization area of ​​the permanent magnet not exceeding 2% to 5% of its surface area. In this embodiment, R1=13mm, inner diameter R2=9mm, according to the parameterized inner diameter function R=R2+H1cos(nθ) of the present invention, it can be known that the inner diameter R=9+H1cos(4θ), where 0≤H1≤4, H1=1mm is selected through finite element analysis, at which time the demagnetization area reaches the minimum value and there is no obvious trend of continued change with the increase of H1, and the surface magnetic waveform does not undergo obvious distortion.

[0054] Example 2

[0055] A bonded NdFeB magnetic ring structure with anti-demagnetization ability is as described in Example 1, except that during the production, NdFeB powder is mixed with a binder such as epoxy resin, phenolic resin, etc. to form a uniform mixture, which is then formed by injection molding, pressing or extrusion. The magnetic ring structure of the present invention can be rapidly produced in batches by designing a mold with a corresponding structure.

[0056] Example 3

[0057] A magnetizing method for a bonded NdFeB magnetic ring structure with anti-demagnetization capability based on Example 1, wherein magnetizing is completed by means of a magnetizing fixture, wherein the magnetizing fixture comprises a positioning base 4, a magnetizing core 2, a winding 3 and an upper cover 5, wherein the magnetizing core 2 is made by a silicon steel sheet lamination process, the winding 3 is made of enameled copper wire, and the positioning base 4 and the upper cover 5 are made of non-magnetic materials such as nylon or aluminum alloy;

[0058] The magnetic ring structure 1 is placed on the magnetizing core 2 and fixed to prevent the magnetic field interaction from rotating during magnetization. A magnetizing power supply is used to pass an instantaneous pulse current through the winding for magnetization. After power is cut off, the magnetic ring structure is removed to complete the magnetization.

[0059] The multi-pole magnetizing fixture matched with the magnetic ring can perform multi-pole magnetization on the magnetic ring in radial direction. After the magnetization is completed, 4 magnetic poles are alternately distributed on the outer surface of the magnetic ring, and the number of magnetic poles is an even number.

[0060] like Figure 7 As shown, the positioning base 4 is a circular structure, with four positioning columns A41 arranged around one side, and a magnetic ring positioning column B42 arranged in the center, and the outer contour of the magnetic ring positioning column B42 is the same as the inner diameter shape of the magnetic ring structure 1;

[0061] like Figure 6 The magnetic core 2 is a circular structure, with four positioning holes 21 arranged around it for passing the positioning column A41 of the positioning base, and a through hole arranged in the center for passing the magnetic ring positioning column B 42 of the positioning base; the magnetic core 2 is evenly provided with four winding holes 231, 232, 233 and 234 around the through hole for installing the winding, such as Fig. 9 The figure shows the winding method of the 4-pole magnetic core. The winding is single-phase, and the two terminals are respectively connected to the positive and negative poles of the pulse power supply. When winding, the winding directions of adjacent teeth are opposite, which can ensure that the magnetic poles are alternately distributed as N poles and S poles.

[0062] A magnetizing tooth portion 22 is formed between two adjacent winding holes. During magnetization, the magnetizing tooth portion 22 corresponds to the position of the main magnetic pole of the magnetic ring structure.

[0063] like Figure 5 As shown, the upper cover 5 is a circular structure with four limiting holes arranged thereon. The positioning column A41 of the positioning base passes through the positioning holes of the magnetic core and the limiting holes of the upper cover in sequence to complete the assembly of the positioning base, the magnetic core and the upper cover.

[0064] The functionalized magnetic ring structure of the present invention requires accurate control of the magnetization position, so a positioning base of a magnetic steel is provided on the multi-pole magnetization fixture to ensure that the magnetic ring with a functionalized inner diameter can be kept fixed in the magnetization fixture according to the position, so that the main magnetic pole position of the magnetic ring is aligned with the magnetization position of the magnetization fixture, ensuring that the main magnetization position during the magnetization process is located in the middle of the magnetic pole.

[0065] The demagnetization results of the bonded NdFeB magnetic ring structure with anti-demagnetization capability of the present invention and the ordinary magnetic ring are analyzed. Fig.10 This is the demagnetization rate distribution cloud diagram of a common 4-pole magnetic ring after the motor is overloaded. Fig.11 The demagnetization ratio distribution cloud diagram of the 4-pole anti-demagnetization magnetic ring of the present invention. A demagnetization ratio of 0 means that no irreversible demagnetization has occurred at this location, and a demagnetization ratio of 100 means that this location has been completely demagnetized. Fig.10 It can be observed that under normal circumstances, there are four locations with smaller demagnetization areas in the magnetic ring (the red areas in the figure). These four locations are located in the transition zone between the main magnetic poles. In a multi-pole magnetic ring, there must be a magnetic pole transition area between the magnetic poles, which is unavoidable. Fig.10 and Fig.11 It can be found from the area of ​​the demagnetized part that the newly added demagnetization area of ​​the bonded NdFeB magnetic ring structure with anti-demagnetization ability after overload is significantly lower than that of the ordinary magnetic ring, and the present invention has obvious anti-demagnetization advantages.

[0066] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bonded NdFeB magnetic ring structure with anti-demagnetization capability, characterized in that: The outer diameter of the magnetic ring structure is a circle, and the inner diameter of the magnetic ring structure is a changing curve, wherein the inner diameter thickness at the main magnetic pole position decreases, and the inner diameter thickness at the transition position between the main magnetic poles increases; The magnetic ring structure adopts bonded NdFeB material.

2. The bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 1, characterized in that: The inner diameter function of the magnetic ring structure satisfies: R = R2 + H1cos (nθ); Wherein, R is the inner diameter function; R2 is the circular inner diameter of the common magnetic ring; H1 is the adjustment parameter, 0≤H1≤(R1-R2), R1 is the circular outer diameter of the common magnetic ring; n is the number of magnetic poles, which is an even number; θ represents the angle.

3. The bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 2, characterized in that: The optimal value of the adjustment parameter H1 is determined by finite element simulation. The optimal value of H1 is based on the new demagnetization area of ​​the permanent magnet not exceeding 2% to 5% of its surface area.

4. The bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 3, characterized in that: During production, NdFeB powder is mixed with a binder to form a uniform mixture, which is then formed by injection molding, pressing or extrusion; Preferably, the binder is, for example, epoxy resin or phenolic resin.

5. A magnetizing method for the bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 4, characterized in that: The magnetization is completed with the help of a magnetization fixture, which includes a positioning base, a magnetization core, a winding and an upper cover. The magnetization core is made of silicon steel sheet lamination process, the winding is made of enameled copper wire, and the positioning base and the upper cover are made of non-magnetic conductive materials; The magnetic ring structure is placed on the magnetizing core and fixed, and a magnetizing power supply is used to pass an instantaneous pulse current into the winding for magnetization. After power is cut off, the magnetic ring structure is taken out to complete the magnetization.

6. The magnetizing method of the bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 5, characterized in that: The positioning base is a circular structure, with n positioning posts A arranged around one side and a magnetic ring positioning post B arranged in the center, and the outer contour of the magnetic ring positioning post B is the same as the inner diameter of the magnetic ring structure; The magnetized core is a circular structure with n positioning holes arranged around it for passing the positioning column A of the positioning base, and a through hole arranged in the center for passing the magnetic ring positioning column B of the positioning base; the magnetized core is evenly provided with n winding holes around the through hole for installing the winding, and a magnetized tooth portion is formed between two adjacent winding holes. During magnetization, the magnetized tooth portion corresponds to the main magnetic pole position of the magnetic ring structure.

7. The magnetizing method of the bonded NdFeB magnetic ring structure with anti-demagnetization capability according to claim 6, characterized in that: The upper cover is a circular structure with n limiting holes arranged thereon. The positioning column A of the positioning base passes through the positioning holes of the magnetic core and the limiting holes of the upper cover in sequence to complete the assembly of the positioning base, the magnetic core and the upper cover.

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