Split type ferrite magnetic core and preparation method thereof

Abstract

The split type ferrite magnetic core comprises an E-shaped magnetic core body and an I-shaped magnetic core body arranged on the opening side of the E-shaped magnetic core body, the E-shaped magnetic core body comprises two U-shaped magnetic core bodies, middle columns of the two U-shaped magnetic core bodies are oppositely arranged, and a splicing seam is arranged at the joint of the middle columns of the two U-shaped magnetic core bodies; the invention further discloses a preparation method of the split type ferrite magnetic core. The structure is composed of the E-shaped magnetic core and the I-shaped magnetic core arranged on the opening side of the E-shaped magnetic core, the E-shaped magnetic core comprises the two U-shaped magnetic cores with the middle columns oppositely arranged, the splicing seam is arranged at the joint of the middle columns of the two U-shaped magnetic cores, and by the adoption of the structure, the eddy-current loss at the positions of the middle columns of the magnetic cores can be greatly reduced, so that the temperature rise during working of the transformer is reduced; due to the fact that the joint of the middle columns of the two U-shaped magnetic cores is provided with the splicing seam, when the temperature changes sharply, stress caused by uneven size stretching can be greatly reduced, and therefore it is guaranteed that when an automobile runs in atrocious weather, a transformer of the automobile cannot break down.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic cores, and in particular relates to a split ferrite magnetic core and a preparation method thereof. Background Art

[0002] As automotive electronic power systems are rapidly developing towards high current, high density, bidirectional and all-in-one integration, the demand for large-sized manganese-zinc power ferrites is increasing, and the core size is also getting larger and larger due to the power requirements of the devices.

[0003] Manganese-zinc power ferrite cores are generally prepared by dry powder molding + high-temperature sintering. Large-sized cores are prone to cracking on the surface of the core or microcracks inside the core due to factors such as difficulty in debinding, stress caused by uneven heating, and structural stress of the core itself during sintering.

[0004] The magnetic cores used in vehicles need to be verified for reliability, such as thermal shock verification at -40 to 125°C (-40 to 150°C is required in special cases), and no cracking after 1,000 cycles. Large-sized magnetic cores are very easy to crack under thermal shock because they have the characteristics of high hardness, low elasticity, and high sintering stress (even microcracks inside the core).

[0005] Therefore, there is an urgent need for a split ferrite core that can reduce the eddy current loss of the transformer, carry more power, and improve the reliability of the transformer working in harsh environments. Summary of the invention

[0006] The purpose of the present invention is to provide a split ferrite core to solve the problems raised in the above background technology. The split ferrite core provided by the present invention has the characteristics of reducing the eddy current loss of the transformer, carrying more power and improving the reliability of the transformer working in harsh environments.

[0007] Another object of the present invention is to provide a method for preparing a split ferrite core.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a split ferrite core, comprising an E-type core and an I-type core arranged on the opening side of the E-type core, wherein the E-type core comprises a U-shaped core with two middle columns arranged opposite to each other, and a splicing seam is provided at the connection between the middle columns of the two U-shaped cores.

[0009] Furthermore, the middle columns of the two U-shaped magnetic cores are bonded by epoxy resin or flexible adhesive.

[0010] In order to adjust the size of the joint seam, an air gap is further provided between the middle columns of the two U-shaped magnetic cores.

[0011] In order to ensure the horizontality of the outer side surface of the center column by cooperating with the support surface and the support fixture when grinding the outer side surface of the center column, further, a support surface is provided on the inner side surface of the center column.

[0012] In the present invention, the method for preparing the split ferrite core further comprises the following steps:

[0013] (i) using a powder forming process to prepare U-shaped magnetic core blanks and I-shaped magnetic core blanks;

[0014] (2) sintering the U-shaped magnetic core blank and the I-shaped magnetic core blank in a nitrogen protection kiln respectively;

[0015] (3) grinding the bottom surface and top surface of the U-shaped magnetic core blank;

[0016] (iv) grinding the outer side surface of the center column of the U-shaped magnetic core blank so that the perpendicularity between the outer side surface of the center column of the U-shaped magnetic core blank and the bottom surface of the magnetic core is ≤0.1 mm, thereby obtaining a U-shaped magnetic core;

[0017] (5) grinding the upper and lower surfaces of the I-type magnetic core blank to obtain an I-type magnetic core;

[0018] (6) splicing the outer side surfaces of the middle columns of the two U-shaped magnetic cores with epoxy resin or flexible glue and curing them to obtain an E-shaped magnetic core;

[0019] (VII) When assembling the transformer, put the coil on the middle column of the E-type magnetic core, and pair the E-type magnetic core with the I-type magnetic core to form a closed magnetic circuit.

[0020] In the present invention, in step (a), the density of the U-shaped magnetic core blank and the I-shaped magnetic core blank are both 3.05±0.10 g / cm 3 , the density difference between each position of the blank is ≤0.08g / cm 3 .

[0021] In the present invention, in step (ii), the sintering temperature is: 1300±30°C, the holding time is: 120±60 minutes, and the oxygen content is 1-6%.

[0022] Furthermore, in the present invention, in step (ii), the deformation amount ΔA of the U-shaped magnetic core blank after sintering is ≤0.5 mm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention is composed of an E-type magnetic core and an I-type magnetic core arranged at the opening side of the E-type magnetic core, and the E-type magnetic core includes two U-type magnetic cores with two middle columns arranged opposite to each other, and a splicing seam is provided at the connection between the middle columns of the two U-type magnetic cores. By adopting this structure, the eddy current loss at the position of the middle column of the magnetic core can be greatly reduced, thereby reducing the temperature rise of the transformer during operation;

[0025] 2. The present invention has a joint seam at the connection of the middle columns of the two U-shaped magnetic cores. When the temperature changes sharply, the stress caused by uneven dimensional expansion and contraction can be greatly reduced, thereby ensuring that the transformer will not fail when the car is driving in bad weather;

[0026] 3. An air gap sheet may be provided between the middle columns of the two U-shaped magnetic cores of the present invention, and the size of the joint seam may be adjusted by using air gap sheets of different thicknesses;

[0027] 4. A support surface is provided on the inner side of the center column of the present invention. When the outer side of the center column is ground, the support surface cooperates with the support jig to ensure the horizontality of the outer side of the center column;

[0028] 5. When preparing the magnetic core, the present invention grinds the top surface of the U-shaped magnetic core blank and the upper and lower surfaces of the I-shaped magnetic core blank respectively, so that there is no gap between the matching surfaces of the I-shaped magnetic core and the E-shaped magnetic core. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention;

[0030] Figure 2 It is a structural schematic diagram of a U-shaped magnetic core of the present invention;

[0031] In the figure: 1, I-type magnetic core; 2, E-type magnetic core; 3, joint seam; 4, U-type magnetic core; 41, middle column; 42, supporting surface. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] See also Figure 1-2 The present invention provides the following technical solution: a split ferrite core, comprising an E-type core 2 and an I-type core 1 arranged on the opening side of the E-type core 2, wherein the E-type core 2 comprises a U-type core 4 with two middle columns 41 arranged opposite to each other, and a joint seam 3 is provided at the connection between the middle columns 41 of the two U-type cores 4.

[0035] By adopting the above technical scheme, the present invention is composed of an E-type magnetic core 2 and an I-type magnetic core 1 arranged on the open side of the E-type magnetic core 2, and the E-type magnetic core 2 includes two U-type magnetic cores 4 with two middle columns 41 arranged opposite to each other, and a splicing seam 3 is provided at the connection between the middle columns 41 of the two U-type magnetic cores 4. By adopting this structure, the eddy current loss at the position of the middle column of the magnetic core can be greatly reduced, thereby reducing the temperature rise of the transformer when it is working; because the splicing seam 3 is provided at the connection between the middle columns 41 of the two U-type magnetic cores 4, the present invention can greatly reduce the stress caused by uneven dimensional expansion and contraction when the temperature changes sharply, thereby ensuring that the transformer of the car will not fail when it is driving in severe weather.

[0036] Specifically, the middle columns 41 of the two U-shaped magnetic cores 4 are bonded together by epoxy resin or flexible adhesive. In this embodiment, epoxy resin is preferably used for bonding.

[0037] Example 2

[0038] The present embodiment is different from the first embodiment in that, specifically, an air gap is provided between the middle columns 41 of the two U-shaped magnetic cores 4 .

[0039] By adopting the above technical solution, the size of the joint seam 3 can be adjusted by using air gap sheets of different thicknesses.

[0040] Example 3

[0041] The present embodiment is different from the first embodiment in that: specifically, a support surface 42 is provided on the inner side surface of the center column 41 .

[0042] By adopting the above technical solution, when grinding the outer side surface of the center column 41 , the horizontality of the outer side surface of the center column 41 is ensured by the cooperation between the support surface 42 and the support fixture.

[0043] Example 4

[0044] Furthermore, the method for preparing a split ferrite core according to the present invention comprises the following steps:

[0045] (i) using a powder forming process to prepare U-shaped magnetic core blanks and I-shaped magnetic core blanks;

[0046] (2) sintering the U-shaped magnetic core blank and the I-shaped magnetic core blank in a nitrogen protection kiln respectively;

[0047] (3) grinding the bottom surface and the top surface of the U-shaped magnetic core blank, using the bottom surface of the U-shaped magnetic core blank as a reference surface, and grinding it to ensure the horizontality of the reference surface;

[0048] (iv) grinding the outer side surface of the center column 41 of the U-shaped magnetic core blank so that the perpendicularity between the outer side surface of the center column 41 of the U-shaped magnetic core blank and the bottom surface of the magnetic core is ≤0.1 mm, thereby obtaining a U-shaped magnetic core 4;

[0049] (V) grinding the upper and lower surfaces of the I-type magnetic core blank so that there is no gap between the mating surfaces of the I-type magnetic core 1 and the E-type magnetic core 2, thereby obtaining the I-type magnetic core 1;

[0050] (VI) splicing the outer side surfaces of the middle columns 41 of the two U-shaped magnetic cores 4 with epoxy resin or flexible glue and curing them to obtain an E-shaped magnetic core 2;

[0051] (VII) When assembling the transformer, the coil is put on the middle column of the E-type magnetic core 2, and the E-type magnetic core 2 is matched with the I-type magnetic core 1 to form a closed magnetic circuit.

[0052] Furthermore, in step (i), the density of the U-shaped magnetic core blank and the I-shaped magnetic core blank is 3.05±0.10 g / cm 3 , the density difference between each position of the blank is ≤0.08g / cm 3 .

[0053] Furthermore, in step (ii), the sintering temperature is: 1300±30°C, the holding time is: 120±60 minutes, and the oxygen content is 1-6%.

[0054] Furthermore, in step (ii), the deformation amount ΔA of the U-shaped magnetic core blank after sintering is ≤0.5 mm.

[0055] In summary, the present invention is composed of an E-type magnetic core 2 and an I-type magnetic core 1 arranged at the opening side of the E-type magnetic core 2, and the E-type magnetic core 2 includes two U-type magnetic cores 4 with two middle columns 41 arranged opposite to each other, and a joint seam 3 is provided at the connection between the middle columns 41 of the two U-type magnetic cores 4. By adopting this structure, the eddy current loss at the position of the middle column of the magnetic core can be greatly reduced, thereby reducing the temperature rise of the transformer when it is working; because the joint seam 3 is provided at the connection between the middle columns 41 of the two U-type magnetic cores 4, the present invention can greatly reduce the stress caused by uneven dimensional expansion and contraction when the temperature changes sharply, thereby ensuring that when the car is driving in bad weather, The transformer will not fail; an air gap sheet can be arranged between the middle columns 41 of the two U-shaped magnetic cores 4 of the present invention, and the size of the joint seam 3 can be adjusted by adopting air gap sheets of different thicknesses; a supporting surface 42 is arranged on the inner side surface of the middle column 41 of the present invention, and when the outer side surface of the middle column 41 is ground, the horizontality of the outer side surface of the middle column 41 is ensured by the cooperation of the supporting surface 42 and the supporting fixture; when preparing the magnetic core, the top surface of the U-shaped magnetic core blank and the upper and lower surfaces of the I-shaped magnetic core blank are ground respectively, so that there is no gap between the matching surfaces of the I-shaped magnetic core 1 and the E-shaped magnetic core 2.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A split ferrite core, Features: It comprises an E-shaped magnetic core and an I-shaped magnetic core arranged at the opening side of the E-shaped magnetic core, wherein the E-shaped magnetic core comprises two U-shaped magnetic cores with two middle columns arranged opposite to each other, and a joint seam is arranged at the connection between the middle columns of the two U-shaped magnetic cores.

2. A split ferrite core according to claim 1, Features: The middle columns of the two U-shaped magnetic cores are bonded by epoxy resin or flexible glue.

3. A split ferrite core according to claim 1, Features: An air gap sheet is arranged between the middle columns of the two U-shaped magnetic cores.

4. The split ferrite core according to claim 1, Features: A supporting surface is provided on the inner side surface of the center column.

5. A method for preparing a split ferrite core according to any one of claims 1 to 4, It is characterized in that The following steps are involved: (i) using a powder forming process to prepare U-shaped magnetic core blanks and I-shaped magnetic core blanks; (2) sintering the U-shaped magnetic core blank and the I-shaped magnetic core blank in a nitrogen protection kiln respectively; (3) grinding the bottom surface and top surface of the U-shaped magnetic core blank; (iv) grinding the outer side surface of the center column of the U-shaped magnetic core blank so that the perpendicularity between the outer side surface of the center column of the U-shaped magnetic core blank and the bottom surface of the magnetic core is ≤0.1 mm, thereby obtaining a U-shaped magnetic core; (5) grinding the upper and lower surfaces of the I-type magnetic core blank to obtain an I-type magnetic core; (6) splicing the outer side surfaces of the middle columns of the two U-shaped magnetic cores with epoxy resin or flexible glue and curing them to obtain an E-shaped magnetic core; (VII) When assembling the transformer, put the coil on the middle column of the E-type magnetic core, and pair the E-type magnetic core with the I-type magnetic core to form a closed magnetic circuit.

6. The method for preparing a split ferrite core according to claim 4, Features: In step (i), the density of the U-shaped magnetic core blank and the I-shaped magnetic core blank are both 3.05±0.10 g / cm3, and the density difference between various positions of the blank is ≤0.08 g / cm3.

7. The method for preparing a split ferrite core according to claim 4, Features: In step (ii), the sintering temperature is: 1300±30°C, the holding time is: 120±60 minutes, and the oxygen content is 1-6%.

8. The method for preparing a split ferrite core according to claim 4, Features: In step (ii), the deformation amount ΔA of the U-shaped magnetic core blank after sintering is ≤0.5 mm.

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