CN104700984A - Choke - Google Patents

Abstract

The invention discloses a choke, which comprises a magnetic core and a hollow coil. The magnetic core comprises a first magnetic core body and a second magnetic core body. The first magnetic core body comprises a center pillar. The second magnetic core body is a flat plate and has an opening, and one end of the center pillar is suitable for being placed into the opening and being connected with the opening. The hollow coil is sleeved on the center pillar.

Description

Choke

The present invention is a divisional application of a Chinese patent application with an application date of July 9, 2009, an application number of 200910158948.9, and an invention title of "choke".

technical field

The invention relates to a passive element, in particular to a choke.

Background technique

The function of the choke is to stabilize the current in the circuit and achieve the purpose of filtering out noise. Its function is similar to that of a capacitor. It also stores and releases the electric energy in the circuit to adjust the stability of the current. Compared with the capacitor, it uses the electric field ( charge) to store electrical energy, and the choke is achieved in the form of a magnetic field.

FIG. 1 is a schematic top view of a conventional choke. The conventional choke 100 has a toroidal core 110 and a wire 120 wound on the toroidal core 110 . The manufacturing method of the choke 100 is as follows: firstly, the magnetic powder (not shown) is pressed into the annular magnetic core 110 . Then, the ring magnetic core 110 is sintered at a temperature of 600° C. or higher. Afterwards, the wire 120 is manually wound on the ring core 110 . However, the choke 100 needs to manually wind the wire 120 on the toroidal core 110 , so it cannot be produced in an automated manner. Therefore, the process of the choke 100 requires considerable labor costs.

Another type of choke is a combined choke, which uses glue to assemble the combined magnetic core. However, during assembly, if the amount of glue is poorly controlled or the surface of the assembly surface of the magnetic core is uneven, the thickness of the glue after assembly is likely to be inconsistent, resulting in large variability in the inductance of the choke. This leads to a drop in pass rate. In order to solve the above problems, a special surface treatment procedure is proposed to enhance the assembly accuracy and increase the assembly surface of the magnetic core, but this increases the manufacturing cost of the choke.

This shows that the above-mentioned existing choke obviously still has inconvenience and defects in structure and use, and needs to be further improved urgently. In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but no suitable design has been developed for a long time, and the general products do not have an appropriate structure to solve the above-mentioned problems. This is obviously the relevant industry. urgent problem to be solved. Therefore, how to create a new type of choke is indeed one of the current important research and development topics, and has also become an urgent need for improvement in the industry.

Contents of the invention

An object of the present invention is to provide a choke with high assembly stability and low inductance variability.

Another object of the present invention is to provide a choke, which utilizes automated equipment to wind wires into hollow coils, which can effectively reduce the labor cost of wires in the winding process (ie, manufacturing process, referred to herein as process).

Another object of the present invention is to provide a choke, which can control the position of the second magnetic core body relative to the first magnetic core body to match different coils to adjust the inductance, so that chokes with different inductances can be Use the same core, saving tooling costs.

Another object of the present invention is to provide a choke, which can effectively reduce the apparent width of the choke and the distance between the ends of the coil when it has a wire groove, and can reduce the distance between the welding pads on the circuit board.

Another object of the present invention is to provide a choke, which sets the opening on the second magnetic core body or the bottom plate with the assembly surface, so that the central column protrudes toward the assembly surface, so that the protruding central column will not affect the choke appearance of the device.

Another object of the present invention is to propose a choke with a housing, a package, a magnetic housing or a magnetic core with a side wall, which can be used to replace the magnetic glue, thereby effectively avoiding the problem of magnetic glue overflow or vertical flow .

The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions.

A method for making an element with an inductance according to the present invention comprises the following steps:

Wrapping a hollow coil with a magnetic glue to form a package;

forming a first magnetic core body; and

At least a part of the first magnetic core body is arranged in the hollow coil of the package body.

In an embodiment of the present invention, the first magnetic core has a top, the top is connected to a column, at least a first part of the column is disposed in the hollow coil of the package and the top is disposed in the package physically.

In one embodiment of the present invention, the following steps are also included:

forming a second magnetic core body; and

The cylinder is connected with the second magnetic core body.

In an embodiment of the present invention, the second magnetic core body has an opening; a second portion of the cylinder is inserted into the opening to be connected with the second magnetic core body.

In an embodiment of the present invention, the packaging body is injection molded or compression molded so that the magnetic material wraps the pre-wound hollow coil.

A method of making a choke according to the present invention comprises the following steps:

Wrapping a hollow coil with a magnetic glue to form a package;

forming a first magnetic core, the first magnetic core includes a center post and a top, the top is connected to one end of the center post; and

At least a first portion of the center post is disposed in the hollow coil of the package, wherein the top is disposed on the package.

In one embodiment of the present invention, further comprising the following steps:

A second magnetic core body is formed, and the second magnetic core body has an opening, and a second part of the center column is disposed in the opening and engaged with the opening.

In an embodiment of the present invention, the second magnetic core body has a joint surface and an assembly surface opposite to the joint surface, and the end of the center post is suitable for being inserted into the opening from the joint surface, The opening is located at the center of the second magnetic core body and communicates with the joint surface and the assembly surface.

In an embodiment of the present invention, the hollow coil has two ends, and the two ends are arranged on the assembly surface, and the second magnetic core body also has two wire grooves, which are located on the second magnetic core The edge of the body, and the two ends pass through the two wire grooves.

In an embodiment of the present invention, the step of forming a material layer is further included, and the material layer is disposed on the inner wall of the opening and is located between the central pillar and the opening.

In an embodiment of the present invention, the second magnetic core body is a flat plate, wherein the second magnetic core body is formed by pressing and sintering, and has a magnetic permeability above 75.

A method of making a choke according to the present invention comprises the following steps:

form a shell;

placing a hollow coil in the housing;

placing a first magnetic core in the hollow coil;

disposing a second magnetic core body in an opening of the housing and engaging with the opening; and

A magnetic glue is arranged in the space between the casing and the hollow coil.

In an embodiment of the present invention, the first magnetic core body includes a top plate and a middle column, the top plate is connected to one end of the center column, the center column and the top plate are integrally formed, and the hollow coil is located on the first Between the top plate of a magnetic core body and the second magnetic core body.

In an embodiment of the present invention, the second magnetic core body has at least one injection hole located at the edge of the second magnetic core body, and the magnetic glue is filled between the casing and the hollow coil through the injection hole within the space.

In an embodiment of the present invention, the housing is made of metal or magnetic material.

A kind of element with inductance proposed according to the present invention is characterized in that, the element with inductance has a plurality of outer surfaces, and the element with inductance includes:

a prewound hollow coil having two ends; and

A magnetic body is disposed in the pre-wound hollow coil, wherein the two ends protrude from the plurality of outer surfaces, and the two ends serve as two pins of the element with inductance and are connected to an external circuit.

In an embodiment of the present invention, the two ends protrude from the same side of a first outer surface of the plurality of outer surfaces to serve as two pins of the inductive element.

In an embodiment of the present invention, the two pins are two through-hole pins.

In an embodiment of the invention, the two pins are surface mount pins.

A choke proposed according to the present invention includes:

a prewound hollow coil having two ends; and

A first magnetic core body is arranged in the pre-wound hollow coil;

an encapsulation body for encapsulating the pre-wound hollow coil and the first magnetic core to form a plurality of outer surfaces of the choke, wherein the two ends protrude from the plurality of outer surfaces, Use as the two pins of the choke and connect to an external circuit.

In an embodiment of the present invention, the first magnetic core body includes a top plate and a center post, the top plate is connected to one end of the center post, and the center post and the top plate are integrally formed.

In an embodiment of the present invention, a magnetic bottom plate is further included, the hollow coil is located between the top plate of the first magnetic core body and the magnetic bottom plate, and the central column is connected with the magnetic bottom plate to form a magnetic core body.

In an embodiment of the present invention, the two pins are two through-hole pins.

In an embodiment of the present invention, the magnetic bottom plate has an opening, wherein a part of the magnetic center column is inserted into the opening and connected with the magnetic bottom plate.

In an embodiment of the present invention, a surface of the bottom plate constitutes a first outer surface of the plurality of outer surfaces, wherein the bottom plate has two wire grooves located at the edge of the bottom plate, and the two ends respectively pass through Pass through the two wire grooves to protrude from the same side of the first outer surface and serve as the two pins of the choke.

Through the above technical solution, the choke provided by the present invention has at least the following advantages and beneficial effects: Based on the above, since the choke provided by the present invention uses automatic equipment to wind the wire into a hollow coil, and then wraps the hollow coil Set on the middle column of the first magnetic core body, and put one end of the middle column into the opening of the second magnetic core body, at this time, the hollow coil is located between the top plate of the first magnetic core body and the second magnetic core body, Thereby completing its assembly. Compared with the prior art, the choke provided by the present invention can not only effectively reduce the labor cost of the wire in the winding process, but also improve the assembly stability and reduce the variability of the inductance value.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1 is a schematic top view of an existing choke;

FIG. 2A is a schematic diagram of a choke according to an embodiment of the present invention;

FIG. 2B is an exploded schematic view of the choke shown in FIG. 2A;

FIG. 2C is a schematic bottom view of the choke shown in FIG. 2A;

3 is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

FIG. 4 is a schematic perspective view of a choke according to another embodiment of the present invention;

5 is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

6A is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

Fig. 6B is a three-dimensional schematic diagram of the magnetic housing of Fig. 6A;

7 is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

8A is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

FIG. 8B is an exploded schematic view of the choke shown in FIG. 8A;

FIG. 8C is a schematic perspective view of the choke shown in FIG. 8A;

FIG. 8D is another exploded schematic view of the choke of FIG. 8A;

FIG. 8E is another exploded schematic view of the choke shown in FIG. 8A;

9 is a schematic cross-sectional view of a choke according to another embodiment of the present invention;

10A to 10D are schematic cross-sectional views of four variations of the magnetic core in FIG. 9 ;

FIG. 11A is a schematic diagram of a choke according to another embodiment of the present invention;

FIG. 11B is an exploded schematic view of the choke shown in FIG. 11A;

Fig. 11C is a schematic diagram of a choke according to another embodiment of the present invention;

FIG. 11D is a schematic diagram of a choke according to another embodiment of the present invention;

Figure 12 is a schematic diagram of the magnetic circuit of the choke.

Description of reference signs: 100, 300a, 300c-300f, 400a-400c, 500a-500e, 600a, 600b, 700a-choke; 110-ring core; 120, 420-wire; 310, 310', 410a- 410c, 510a～510d, 610-magnetic core; 311, 311', 611, 611', 711a-the first magnetic core body; 312, 414, 414', 414", 512a～512e, 614, 614', 714a- Middle column; 312a, 312b, 513b～513e, 614a, 614a'-one end; 314, 314', 412, 412', 514b～514e, 612, 612'-top plate; 314a, 612a, 612a'-bottom; 314b, 612b, 612b', 712a-side wall portion; 315, 315', 617, 617', 717a-second magnetic core body; 315a, 416a, 518a, 617a-joint surface; 315b, 416b, 518b, 617b-assembly surface ; 316, 517, 619-opening; 317a, 317b, 616-wire groove; 318, 416c-injection hole; 320, 522, 620-hollow coil; 322, 324-end; 323-winding part; 330-material layer; 340, 440-magnetic glue; 350, 430-shell; 352, 432-open end; 360-magnetic shell; 360a-upper surface; 360b-lower surface; 362a, 362b-open end; 416, 416' , 416", 516d, 516e-bottom plate; 370, 520-package body; 520a-surface; 524-magnetic material; 526-through hole; S-winding space.

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation, structure, characteristics and effects of the choke proposed according to the present invention will be described below in conjunction with the accompanying drawings and preferred embodiments. Details are as follows.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the drawings. Through the description of specific embodiments, a more in-depth and specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are only for reference and description, and are not used to explain the present invention. be restricted.

As shown in Figure 2A and Figure 2B, Figure 2A is a schematic diagram of a choke according to an embodiment of the present invention, Figure 2B is an exploded schematic diagram of the choke in Figure 2A, and Figure 2C is a bottom view of the choke in Figure 2A schematic diagram. In this embodiment, the choke 300 a includes a magnetic core 310 and a hollow coil 320 , wherein the magnetic core 310 includes a first magnetic core body 311 and a second magnetic core body 315 .

The first magnetic core 311 includes a central column 312 and a top plate 314 , wherein an end 312 b of the central column 312 is connected to the top plate 314 to form a T-shaped structure, and the central column 312 and the top plate 314 are integrally formed. The second magnetic core body 315 is a flat plate, and has a joint surface 315a, an assembly surface 315b opposite to the joint surface 315a, an opening 316, and two opposite sides of the opening 316 and located on the second magnetic core body. Wire slots 317a, 317b on the edge of 315. The opening 316 is located at the center of the second magnetic core body 315 and communicates with the joint surface 315a and the assembly surface 315b, wherein one end 312a of the center post 312 of the first magnetic core body 311 is suitable for being inserted into the opening 316 from the joint surface 315a and is connected to the opening 316 are engaged. The connection between the end 312a of the center post 312 and the opening 316 can be a tight fit or an adhesive connection. In this embodiment, the cross-sectional shapes of the top plate 314, the second magnetic core body 315 and the opening 316 are all circular, and the middle column 312 is a cylinder, but it is not limited thereto. For example, the top plate 314, the second The shape of the magnetic core body 315 and the opening 316 can also be rectangular, and the central column 312 is a rectangular column.

The material of the magnetic core 310 is ferrite material, iron or low magnetic loss material. Ferrite materials include Ni-Zn ferrite or Mn-Zn ferrite. The low magnetic loss material may be iron-containing alloy, wherein the iron-containing alloy may be sendust, iron-nickel-molybdenum alloy, iron-nickel alloy or amorphous (Amorous) alloy. It is worth noting that using low magnetic loss material as the magnetic core 310 can increase the magnetic permeability and achieve low iron loss. In this embodiment, the first magnetic core body 311 and the second magnetic core body 315 in the magnetic core 310 are made of ferrite (ferrite) material, and the magnetic permeability of the magnetic core 310 can be above 75. Specifically, the magnetic core 310 is A ferrite powder is used to mix a binder, which is formed by pressure molding and firing. The binder includes Polymethylallyl (PMA) Synthesize resin.

It must be noted here that, during the process of the first magnetic core body 311 and the second magnetic core body 315, due to the influence of the process tolerance, a gap is likely to be generated at the joint between the central column 312 and the opening 316, as shown in FIG. 2C As shown, that is, the diameter of the opening 316 is larger than the diameter of the center post 312 . Therefore, in this embodiment, a material layer 330 can be selectively coated on the inner wall of the opening 316, that is, the material layer 330 is located between the central column 312 and the opening 316, so as to reduce the distance between the central column 312 and the opening 316 during assembly. The influence of the spacing between them on the inductance value, in order to improve the assembly stability and reduce the variability of the inductance value. In addition, the material layer 330 may be resin colloid or magnetic colloid. It should be noted that the material layer 330 can be directly used as an adhesive when the end 312a of the center column 312 is joined with the opening 316 by glue.

The hollow coil 320 is sheathed on the center column 312 of the first magnetic core body 311 , and is located between the top plate 314 of the first magnetic core body 311 and the joint surface 315 a of the second magnetic core body 315 . Specifically, this embodiment utilizes automatic equipment to wind the wire into a hollow coil 320, wherein the wire can be a round wire (the minimum cross-sectional area is a circle) or a flat wire (the minimum cross-sectional area is a rectangle), and the wire can be made of copper The outer coating of the wire is composed of an enamelled layer, and the enameled layer is an insulating layer. Specifically, the hollow coil 320 has two ends 322, 324 and a winding portion 323 located between the two ends 322, 324, and the winding portion 323 is wound on the central column 312 of the first magnetic core body 311 , and the two ends 322 , 324 pass through the wire slots 317 a , 317 b of the second magnetic core body 315 and are disposed on the assembly surface 315 b. The two ends 322, 324 of the hollow coil 320 can be directly used as external electrodes or connected to a lead frame (lead frame) as external electrodes, and the external electrodes can be fixed with a through-hole mount or a surface mount. The external circuit is electrically connected.

It is worth mentioning that the second magnetic core body 315 is directly pressed on the hollow coil 320, so that the second magnetic core body 315 is directly arranged on the hollow coil 320, so the second magnetic core body 315 can be positioned by the height of the hollow coil 320. Core 315 position. And one end 312a of the central column 312 of the first magnetic core body 311 in this embodiment is substantially aligned with the assembly surface 315b of the second magnetic core body 315, but in other embodiments, as shown in Figure 3, the first One end 312a of the central column 312 of the magnetic core body 311 passes through the opening 316 of the second magnetic core body 315 and protrudes from the assembling surface 315b, which still belongs to the applicable technical solution of the present invention and does not depart from the protection scope of the present invention. In FIG. 3 , the height of the central column 312 protruding from the assembly surface 315b is lower than the length of the two ends 322, 324 of the hollow coil 320 extending to the outside of the wire grooves 317a, 317b, so as to prevent the central column 312 from affecting the ends 322, 324. Electrical connections to external circuits.

In addition, the choke 300a in this embodiment can optionally fill a magnetic glue 340 between the first magnetic core body 311 and the second magnetic core body 315 and wrap the winding portion 323 and the end portion of the hollow coil 320 A part of 322, 324, the uncoated ends 322, 324 are used for electrical connection with external circuits. The magnetic glue 340 includes a resin material and a magnetic powder material, wherein the magnetic powder material accounts for more than 70 percent of the total weight of the magnetic glue 340 , and the magnetic permeability of the magnetic glue 340 can be above 6, but not limited thereto. The resin material can be selected from polyamide 6 (Polyamide 6, PA6), polyamide 12 (Polyamide 12, PA12), polyphenylene sulfide (Polyphenylene Sulfide, PPS), polybutylene terephthalate (polybutyleneterephthalate, PBT) or One of the ethylene-ethyl acrylate copolymers (EEA). The magnetic powder material can be metal soft magnetic material or ferrite powder (Ferrite), wherein the metal soft magnetic material can be selected from iron powder (Iron), FeAlSi Alloy, FeCrSi Alloy or one of stainless steel.

Since the choke 300a in this embodiment is to use the automatic equipment to wind the wire into the hollow coil 320, then the hollow coil 320 is set on the center column 312 of the first magnetic core body 311, and then the center column 312 One end 312a is put into the opening 316 of the second magnetic core body 315, thereby completing the assembly. Compared with the existing choke 100, the choke 300a in this embodiment can effectively reduce the labor cost of the wire in the winding process.

In addition, the present invention can control the position of the second magnetic core body 315 relative to the first magnetic core body 311 to match different hollow coils to adjust the inductance, so that chokes with different inductances can use the same magnetic core, thereby Save mold costs. Moreover, the opening 316 is arranged on the second magnetic core body 315 having the assembly surface 315b, so that when the inductance value is adjusted by using the position of the second magnetic core body 315, the center column 312 can protrude toward the assembly surface 315b, so that the protruding The center column 312 does not affect the appearance of the choke 300a. In addition, since the second magnetic core body 315 has wire slots 317a, 317b for the two ends 322, 324 of the hollow coil 320 to pass through, the distance between the two ends 322, 324 and the appearance of the choke 300a can be reduced. width, and when the two ends 322, 324 are used as external electrodes, the distance from the pads of the circuit board can be effectively reduced.

As shown in FIG. 2A and FIG. 4 , FIG. 4 is a perspective view of a choke according to another embodiment of the present invention. The choke 300c in FIG. 4 is similar to the choke 300a in FIG. 2A, except that the choke 300c in FIG. The core body 315' also has at least one injection hole 318 (only two are schematically shown in FIG. 4 ) located at the edge of the second magnetic core body 315', wherein the housing 350 is a barrel-shaped structure, and the magnetic core 310' is hollow The coil 320 is disposed in the casing 350, and the second magnetic core body 315' is disposed at the open end 352, and the open end 352 exposes the assembly surface 315b of the second magnetic core body 315', and the magnetic glue 340 is suitable for passing through the injection hole 318 is filled in the casing 350 to be arranged in the space between the casing 350 and the hollow coil 320, and covers the hollow coil 320, the central column 312 and the top plate 314 of the first magnetic core body 311 and part of the second magnetic core Body 315'.

Since the choke 300c in this embodiment has a housing 350, when the magnetic glue 340 is filled, there will be no problem of overflow or sagging (especially if the height of the choke 300c is higher, such as 10 centimeters (mm) above), the appearance of the choke 300c is also more beautiful and can cover the cracks of the magnetic glue 340 (due to the difference in thermal expansion coefficient between the resin material and the copper wire, resulting in cracks on the surface of the choke) and prevent rust. In addition, if the material of the casing 350 is metal or magnetic material, the choke 300c also has the effect of preventing electromagnetic interference. If the material of the housing 350 is metal, the heat dissipation can reduce the overall temperature of the choke 300c, thereby improving the efficiency.

As shown in FIG. 2A and FIG. 5 , FIG. 5 is a schematic cross-sectional view of a choke according to another embodiment of the present invention. The choke 300d among Fig. 5 is similar to the choke 300a among Fig. 2A, and its difference is: the manufacture of the choke 300d among Fig. 5 is to adopt injection molding (injection molding) or compression molding (press molding) to wrap the magnetic glue 340 around the hollow coil 320 to form a package 370, and then, the package 370 is sleeved on the center post 312, so that one end 312a of the center post 312 of the first magnetic core body 311 Pass through the hollow coil 320 and the second magnetic core body 315 , and align with the assembly surface 315 b of the second magnetic core body 315 , so as to complete the assembly of the choke 300 d. Since the choke 300d in this embodiment is firstly coated with the magnetic glue 340 on the hollow coil 320 to form the package 370, and then assembled on the magnetic core 310, problems of glue overflow or drooping can be avoided. Moreover, the magnetic glue is formed by injection molding and compression molding, so that the density of the magnetic glue in the package body 370 can be increased to increase the magnetic permeability. Therefore, under the same inductance value, the choke 300d can be compared with the chokes 300a and 300c. Has a smaller volume.

As shown in FIG. 2A , FIG. 6A and FIG. 6B , FIG. 6A is a schematic cross-sectional view of a choke according to another embodiment of the present invention, and FIG. 6B is a schematic perspective view of the magnetic housing in FIG. 6A . The choke 300e of FIG. 6A is similar to the choke 300a of FIG. 2A, the difference is that the choke 300e in FIG. 6A replaces the magnetic glue 340 of FIG. 2A by a magnetic housing 360, wherein the magnetic housing 360 has an upper surface 360a, a lower surface 360b opposite to the upper surface 360a, and two open ends 362a, 362b. The open ends 362a, 362b are respectively located on the upper surface 360a and the lower surface 360b, and the open ends 362a, 362b communicate with each other. In detail, the hollow coil 320 is disposed in the magnetic housing 360, and the central column 312 of the first magnetic core body 311 passes through the open ends 362a, 362b of the magnetic housing 360, so that the top plate 314 of the first magnetic core body 311 bears The second magnetic core body 315 is disposed on the lower surface 360 b of the magnetic housing 360 against the upper surface 360 a of the magnetic housing 360 . Since the magnetic glue 340 is replaced by the magnetic shell 360 in the choke 300e in this embodiment, there is no problem of glue overflow or drooping.

As shown in FIG. 2A and FIG. 7 , FIG. 7 is a schematic cross-sectional view of a choke according to another embodiment of the present invention. The choke 300f in FIG. 7 is similar to the choke 300a in FIG. 2A, the difference is that the top plate 314' of the first magnetic core body 311' of the choke 300f in FIG. 7 has a bottom 314a and The two sidewalls 314b are disposed on opposite sides of the bottom 314a, and the extending direction of the sidewalls 314b is substantially perpendicular to the extending direction of the bottom 314a. The extending direction of the sidewalls 314b is parallel to the extending direction of the central column 312 , the height of the sidewalls 314b may be the same as that of the central column 312 , and the second magnetic core 315 is disposed between the sidewalls 314b. The magnetic glue 340 is filled between the sidewalls 314 b of the first magnetic core body 311 , and covers the winding portion 323 and some ends of the hollow coil 320 (not shown). The choke 300f in this embodiment is provided with the side wall portion 314b, so the problem of overflowing or drooping of the magnetic glue 340 can be improved.

As shown in Figure 8A, Figure 8B and Figure 8C, Figure 8A is a schematic cross-sectional view of a choke in another embodiment of the present invention, Figure 8B is an exploded schematic view of the choke in Figure 8A, and Figure 8C is a schematic diagram of the choke in Figure 8A A three-dimensional schematic diagram of a choke. It should be noted here that, for convenience of illustration, the magnetic glue 340 is omitted in FIG. 8B . In this embodiment, the choke 400 a includes a magnetic core 410 a, at least one wire 420 and a housing 430 . In detail, the magnetic core 410a includes a top plate 412, a central column 414, and a bottom plate 416, and the bottom plate 416 has a joint surface 416a, an assembly surface 416b opposite to the joint surface 416a, and at least one injection hole 416c (in FIG. 8C Two are schematically shown), wherein the central column 414 is disposed between the top plate 412 and the bottom plate 416 , and a winding space S is formed between the top plate 412 , the central column 414 and the bottom plate 416 . The material and manufacturing method of the magnetic core 410 a are the same as those of the magnetic core 310 , so details will not be repeated here. In this embodiment, the top plate 412 , the central column 414 and the bottom plate 416 of the magnetic core 410 a are integrally formed to form a drum-core structure.

The wire 420 is wound on the central column 414 and is located in the winding space S, wherein the wire 420 can be a round wire (the smallest cross-sectional area is a circle) or a flat wire (the smallest cross-sectional area is a rectangle), and the wire 420 can be made of copper wire The outer coating is composed of an enamelled layer, and the enamelled layer is an insulating layer. In addition, the wire 420 can be wound on the central column 414 of the magnetic core 410a by using automatic equipment, and the number of the wire 420 is not limited in this embodiment, that is, there can be one or more wires 420 .

The casing 430 is a barrel-shaped structure with an open end 432, wherein the magnetic core 410a and the wire 420 are disposed in the casing 430, and the open end 432 exposes the assembly surface 416b of the bottom plate 416 of the magnetic core 410a.

In addition, the choke 400a in this embodiment also includes a magnetic glue 440, wherein the magnetic glue 440 is suitable to be filled into the casing 430 through the injection hole 416c, so as to fill the winding space S and cover the wire 420 and part of the magnet. Core 410a. The material of the magnetic glue 440 is the same as that of the magnetic glue 340 , so it will not be repeated here.

Since the choke 400a in this embodiment has a housing 430, there will be no overflow or sag when the magnetic glue 430 is filled, and the appearance of the choke 400a is also more beautiful and can cover the cracks of the magnetic glue And prevent rust. In addition, when the material of the housing 430 is metal or magnetic material, the choke 400a can prevent electromagnetic interference. When the material of the housing 430 is metal, the heat dissipation can reduce the overall temperature of the choke 400a, thereby improving the efficiency.

It is worth mentioning that the present invention does not limit the shape of the magnetic core 410a. In other embodiments, as shown in FIG. It consists of a bottom plate 416', wherein the central column 414' and the top plate 412' are integrally formed, and the bottom plate 416' is connected to one end of the central column 414' by means of bonding, or the central column 414', the top plate 412' and the bottom plate 416' are all They are connected by bonding, and the wire 420 is a hollow coil and is sheathed on the center post 414'. As shown in Figure 8E, the magnetic core 410c of the choke 400c can also be composed of a central column 414" and a bottom plate 416", wherein the wire 420 is a hollow coil and is sleeved on the central column 414", which still belongs to the present invention. The technical solutions that can be adopted by the invention do not depart from the intended protection scope of the present invention.

As shown in FIG. 9 , FIG. 9 is a schematic cross-sectional view of a choke according to another embodiment of the present invention. In this embodiment, the choke 500a includes a magnetic core 510a and a package body 520, wherein the magnetic core 510a includes a center post 512a, and the package body 520 is sleeved on the center post 512a of the magnetic core 510a, and the package body 520 includes a hollow coil 522 and a magnetic material 524 covering the hollow coil 522 . The package body 520 is formed by making the magnetic material 524 wrap around the hollow coil 522 by injection molding or press molding, and the package body 520 has a through hole 526 for setting the magnetic core 510a. Center column 512a. In this embodiment, the height of the package body 520 is equal to the length of the central column 512b, so that both ends of the central column 512b are aligned with the surface of the package body 520 . The material of the magnetic core 510 a is the same as that of the magnetic core 310 , the hollow coil 522 is the same as the hollow coil 320 , and the material of the magnetic material 524 is the same as that of the magnetic glue 340 , so details will not be repeated here.

The fabrication of the choke 500a in this embodiment is to form the package body 520 first, and then pass the center column 512a of the magnetic core 510a through the hollow coil 522 to form the choke 500a. The choke 500a in this embodiment can achieve the same effect as the choke 300d, so it will not be repeated here.

The structure of the magnetic core 510 a is not limited to the structure disclosed in FIG. 9 , and the magnetic core 510 a may also be the structure disclosed in FIGS. 10A to 10D . In detail, as shown in FIG. 10A , the magnetic core 510b of the choke 500b further includes a top plate 514b, wherein the central post 512b and the top plate 514b are integrally formed, and one end 513b of the central post 512b is sleeved in the package body 520, That is, one end 513b of the center post 512b is not exposed outside the package body 520, and the height of the package body 520 is greater than the length of the center post 512b. As shown in FIG. 10B , the magnetic core 510c of the choke 500c further includes a top plate 514c, wherein the central column 512c is integrally formed with the top plate 514c, and one end 513c of the central column 512c passes through the package body 520 and is away from the package body 520 from the top plate. A surface 520a of 514c is substantially flush. As shown in FIG. 10C , the magnetic core 510d of the choke 500d further includes a top plate 514d and a bottom plate 516d, wherein the top plate 514d and the center column 512d are integrally formed, and one end 513d of the center column 512d passes through the package body 520 and is packaged A surface 520 a of the body 520 away from the top plate 514 d is substantially aligned, and the bottom plate 516 d covers the end 513 d of the central column 512 d and the surface 520 a of the package body 520 . As shown in Figure 10D, the magnetic core 510e of the choke 500e also includes a top plate 514e and a bottom plate 516e, wherein the top plate 514e and the center column 512e are integrally formed, and the bottom plate 516e has an opening 517, a joint surface 518a opposite to The assembly surface 518b on the joint surface 518a. One end 513e of the central column 512e passes through the package body 520 and is inserted into the opening 517 from the bonding surface 518a, and the one end 513e of the central column 512e is substantially aligned with the assembly surface 518b.

As shown in FIG. 11A and FIG. 11B , FIG. 11A is a schematic diagram of a choke according to another embodiment of the present invention, and FIG. 11B is an exploded schematic diagram of the choke in FIG. 11A . In this embodiment, the choke 600 a includes a magnetic core 610 and a hollow coil 620 . In detail, the magnetic core 610 includes a first magnetic core body 611 and a second magnetic core body 617 . The first magnetic core body 611 includes a top plate 612, a central column 614 and at least one wire groove 616 (two are schematically shown in FIG. 11A ), wherein the central column 614 and the top plate 612 are integrally formed, and the top plate 612 has a bottom 612 a and a side wall portion 612 b disposed around the bottom 612 a , and the side wall portion 612 b surrounds the central column 614 . The diameter of the central column 614 is smaller than the length of one side of the bottom 612a of the top plate 612, and the extension direction of the side wall portion 612b is substantially perpendicular to the extension direction of the bottom 612a. The extension direction of the side wall portion 612 b is parallel to the extension direction of the central column 614 . The wire slot 616 is disposed on the side wall portion 612 b of the top plate 612 , and the width of the wire slot 616 can be designed according to the wire diameter of the hollow coil 620 .

The second magnetic core body 617 is a flat plate and has a joint surface 617 a , an assembly surface 617 b opposite to the joint surface 617 a and an opening 619 . The opening 619 is located at the center of the second magnetic core body 617 and communicates with the joint surface 617 a and the assembly surface 617 b. One end 614a of the center post 614 is adapted to be inserted into the opening 619 from the joint surface 617a. In particular, the height of the side wall portion 612b of the top plate 612 may be the same as that of the center column 614, and the second magnetic core 617 is disposed between the side wall portions 612b. The material of the magnetic core 610 in this embodiment is the same as that of the magnetic core 310 , so details will not be repeated here. In this embodiment, the central column 614 can be a cylinder, the shape of the second magnetic core body 617, the opening 619, and the bottom 612a of the top plate 612 can be circular, and the diameter of the opening 619 is greater than or equal to the diameter of the central column 617 .

The hollow coil 620 is sleeved on the central column 614 and is located between the top plate 612 of the first magnetic core body 611 and the second magnetic core body 617, wherein the height of the hollow coil 620 is smaller than the height of the side wall portion 612b of the top plate 612, and The side wall portion 612b is in contact with at least part of the hollow coil 620 . The manufacturing method, material and structure of the hollow coil 620 are the same as those of the hollow coil 320 , so details will not be repeated here.

It is worth mentioning that the second magnetic core body 617 in this embodiment is directly pressed onto the hollow coil 620, so that the second magnetic core body 617 is directly arranged on the hollow coil 620, so the height of the hollow coil 620 can be passed To locate the position of the second magnetic core body 617, and in this embodiment, one end 614a of the middle column 614 of the first magnetic core body 611 is substantially aligned with the assembly surface 617b of the second magnetic core body 617, but in other embodiments Among them, one end 614a of the central column 614 of the first magnetic core body 611 can pass through the opening 619 of the second magnetic core body 617 and protrude from the assembly surface 617b, wherein the height of the central column 614 protruding from the assembly surface 617b is lower than that of the hollow coil 620 The length of the two ends extending to the outside of the wire groove 616 still belongs to the applicable technical solution of the present invention and does not depart from the intended protection scope of the present invention.

In addition, in this embodiment, a material layer 630 can be selectively coated at the intersection of the center post 614 and the opening 619 to reduce the influence of the distance between the center post 614 and the opening 619 on the inductance value during assembly. In addition, the material layer 630 may be resin colloid or magnetic colloid. Of course, in a preferred embodiment, the diameter of the central column 614 of the first magnetic core body 611 is equal to the diameter of the opening 619 of the second magnetic core body 617 .

In addition, the present invention does not limit the shape of the first magnetic core body 611 and the second magnetic core body 617, although the shape of the bottom 612a of the top plate 612 of the first magnetic core body 611 mentioned here is circular, and the second The shape of the magnetic core body 617 is circular, but in other embodiments, as shown in FIG. 11C , the bottom 612a' of the top plate 612' of the first magnetic core body 611' can also be rectangular, and the side wall portion 612b' surrounds The bottom 612a' is disposed around the rectangle, and the second magnetic core 617' is disposed inside the side wall 612b' and is circular in shape, which still belongs to the applicable technical solution of the present invention and does not depart from the intended protection scope of the present invention.

The choke 600a in this embodiment is to use automatic equipment to wind the wire into a hollow coil 620, and then the hollow wire 620 is sleeved on the center column 614 of the first magnetic core body 611, and one end of the center column 614 614a is put into the opening 619 of the second magnetic core body 617, and the hollow coil 620 is located between the top plate 612 of the first magnetic core body 611 and the second magnetic core body 617, thereby completing the assembly. Compared with the prior art, the choke 600a in this embodiment can effectively reduce the labor cost of the wire in the winding process, and can also selectively coat the material layer 630 on the center post 614 and The junction of the opening 619 is used to improve assembly stability and reduce inductance variability.

Since the choke 600a in this embodiment utilizes the side wall portion 612b of the top plate 612 to cover the periphery of the hollow coil 620 to replace the magnetic glue, so in addition to the problem of glue overflow or sagging, the process can also be reduced. steps to reduce manufacturing costs. In addition, different hollow coils can be matched by controlling the position of the second magnetic core body 617 relative to the first magnetic core body 611 to adjust the inductance, so that chokes with different inductances can use the same magnetic core, thereby saving molds cost. Moreover, the opening 619 is arranged on the second magnetic core body 617 having the assembly surface 617b, so that when the inductance value is adjusted by using the position of the second magnetic core body 617, the center column 614 can protrude toward the assembly surface 617b, so that the protruding The center post 617 does not affect the appearance of the choke 600a.

In addition, as shown in FIG. 11A and FIG. 11D , FIG. 11D is a schematic cross-sectional view of a choke according to another embodiment of the present invention. The choke 600b in FIG. 11D is similar to the choke 600a in FIG. 11A, except that the side wall portion of the first magnetic core body 611' of the magnetic core 610' of the choke 600b in FIG. 11D The height of 612b' is lower than the height of central column 614', and one end 614a' of central column 614' is adapted to be inserted into opening 619 from joint surface 617a of second magnetic core body 617, and the two ends of second magnetic core body 617 It is disposed on the side wall portion 612b ′, that is, the second magnetic core body 617 can be positioned through the side wall portion 612b ′. In this embodiment, the side wall portion 612b' is also used instead of the magnetic glue, so that in addition to avoiding the problem of glue overflow or sagging, the process steps can be reduced to reduce the manufacturing cost.

The actual measurement results will be presented below to compare the conventional choke 100 of FIG. 1 with the partial chokes 300a, 300c, 300d, 600a, 600b of this embodiment.

[The first set of measured results]

This actual measurement is to compare the existing choke 100 with the same magnetic core material and similar volume and the choke 300a in FIG. 2A of this embodiment. Table 1 shows the experimental data of the choke 100 and three identical chokes 300 a obtained by converting the power supply output from 12 volts to 5 volts. Table 2 shows the experimental data of the choke 100 and three identical chokes 300 a obtained by converting the output of the power supply from 12 volts to 3.3 volts.

Table I

Table II

According to Table 1 and Table 2, under the same current of the choke 100 and the choke 300a, the efficiency of the choke 300a is higher than that of the conventional choke 100 . In other words, the design of the magnetic core 310 of the choke 300 a is progressive compared with the design of the magnetic core of the conventional choke 100 .

[Second set of measured results]

This actual measurement is to compare the existing choke 100 with the same magnetic core material and similar volume and the choke 300c in FIG. 4 of this embodiment. Table 3 shows the experimental data of the choke 100 and four identical chokes 300c obtained by converting the output of the power supply from 12 volts to 5 volts, and Table 4 shows the experimental data of the choke 100 obtained by converting the output of the power supply from 12 volts to 3.3 volts. Experimental data for four identical chokes 300c.

Table three

Table four

According to Table 3 and Table 4, under the same current of the choke 100 and the choke 300c, the efficiency of the choke 300c under light load (50% load) is higher than that of the conventional choke 100 .

[The third set of measured results]

This actual measurement is to compare the existing choke 100 with the same magnetic core material and similar volume and the choke 300d in FIG. 5 of this embodiment. Table 5 shows the experimental data of the choke 200 and the choke 300d obtained by converting the output of the power supply from 12 volts to 3.3 volts.

Table five

According to Table 5, under the same current of the choke 100 and the choke 300d, the efficiency of the choke 300d is higher than that of the conventional choke 100 under light load and heavy load.

[The fourth set of measured results]

This actual measurement is an experiment aimed at the effect of the unilateral spacing between the central post 312 and the opening 316 on the initial inductance of the choke 300a, wherein the thickness of the second magnetic core 315 is 2.5 centimeters (mm). Table 6 shows the experimental data of the initial inductance of the choke 300a with respect to the unilateral spacing.

Table six

According to Table 6, when the unilateral spacing is 0.1 centimeter (mm), the initial inductance decreases by 6.91%; when the unilateral spacing is larger (for example, 0.4 cm (mm)), the initial inductance decreases (17.51%) ). That is to say, during the manufacturing process of the choke 300a, the distance between the junction of the center post 312 and the opening 316 will affect the variability of the inductance.

In the following, the initial inductance of the choke 310 a by the filling material layer 340 at the junction of the center post 312 and the opening 316 will be tested, wherein the thickness of the second magnetic core 315 is 2.5 centimeters (mm). Table 7 shows the experimental data of the thickness of the material layer on the initial inductance.

Table seven

According to Table 7, it can be seen that when the thickness of the magnetic material layer 330 is increased from 0.1 centimeter (mm) to 0.4 centimeter (mm), the amount of change in inductance is still less than 5%, that is to say, compared to FIG. The influence of the thickness on the initial sensitivity is smaller than the influence of the distance between the junction of the central column 312 and the opening 316 on the initial sensitivity. In other words, the selective filling material layer 330 can be provided to reduce the variability of the sensing value caused by the process tolerance.

The following experiment is carried out with the thickness of the second magnetic core body 315 being 3 centimeters (mm). Table 8 shows the experimental data of the thickness of the material layer on the initial inductance.

table eight

According to Table 8 and Table 7, it can be known that when the second magnetic body 315 increases from 2.5 centimeters (mm) to 3 centimeters (mm), the amount of change in inductance is only 0.81% higher than that of 2.5 centimeters (mm), and the material layer 330 When the thickness is 0.4 centimeters (mm), the influence of inductance is still less than 5%, that is to say, the coating material layer 330 at the junction of the center column 312 and the opening 316 has a greater influence on the inductance than increasing the thickness of the second magnetic core body 315. efficient.

[Fifth group of measured results]

This actual measurement is to simulate the influence of the presence or absence of the wire groove 616 on the inductance of the choke 600a in FIG. ). From the simulation results, it can be seen that when the choke 600a has no wire slot 616, the inductance is about 3.3 micro-Henry (μH); when the choke 600a has the wire slot 616, the inductance is about 3.43 micro-Henry (μH), That is to say, with or without the wire groove 616, the inductance difference is 4%.

Next, an experiment was conducted on the influence of the width of the wire groove 616 on the inductance, wherein the material of the first magnetic core body 611 of the choke 600 a is sendust with a magnetic permeability of 125. Table 9 shows the experimental data of the distance between wire grooves and inductance.

Table nine

According to Table 9, it can be seen that when the pitch of the wire slots 616 is changed from 1.6mm to 4.8mm, the drop rate of the inductance of the choke 600a is below 3%. It can be seen that the setting of the wire groove 616 has little influence on the inductance.

[The sixth group of measured results]

The experiment of the equivalent magnetic circuit is carried out below for the choke 600 a of FIG. 11A and the choke 600 b of FIG. 11D , wherein the magnetic cores of these chokes have the same material and size. Fig. 12 is a schematic diagram of the magnetic circuit of the choke. For convenience of description, Fig. 12 only shows the first magnetic core body and the second magnetic core body of the magnetic core, and Fig. 12(a) represents that the second magnetic core body 717a is located at the On the center column 714a and the side wall portion 712a of a magnetic core body 711a, and the second magnetic core body 717a has no opening, FIG. 12(c) represents the choke 600b, that is, the two ends of the second magnetic core body 617 are disposed on the side wall portion 612b'. Thin dotted lines represent pitches (only one side is shown), and thick dotted lines represent equivalent magnetic circuit paths (only one side is shown). Table 10 shows the experimental data of the unilateral spacing on the permeability of the equivalent magnetic circuit.

table ten

According to Table 10, the choke 600a has the smallest influence on the magnetic permeability, the choke 600b takes the second place, and the choke 700a has the greatest influence on the magnetic permeability. It can be seen that the choke 600a and the choke 600b proposed by the present invention can effectively reduce the influence of the unilateral spacing on the magnetic permeability, so that the choke 600a, 600b has a larger inductance than the choke 700a.

In summary, the chokes 300a, 300c-300f, 400a-400c, 500a-500e, 600a, 600b provided by the present invention have at least the following advantages:

1. The assembly stability of the choke is high, which can reduce the variability of the inductance value.

2. The efficiency of the choke provided by the present invention is greater than that of the existing choke.

3. Automatic equipment can be used to wind the wire into a hollow coil, which can effectively reduce the labor cost of the wire in the winding process.

4. The position of the second magnetic core body relative to the first magnetic core body can be controlled to match different coils to adjust the inductance, so that chokes with different inductances can use the same magnetic core, thereby saving mold costs.

5. When the choke has a wire groove, the apparent width of the choke and the distance between the ends of the coil can be effectively reduced, and the distance between the welding pads on the circuit board can be reduced.

6. The opening is provided on the second magnetic core body or the bottom plate with the assembling surface, so that the central column protrudes toward the assembling surface, so that the protruding central column will not affect the appearance of the choke.

7. The choke has a shell, a package, a magnetic shell or a magnetic core with a side wall, which can be used to replace the magnetic glue, so as to effectively avoid the problem of overflow or vertical flow of the magnetic glue.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this professional technology Personnel, without departing from the scope of the technical solution of the present invention, when the technical content disclosed above can be used to make some changes or modifications to equivalent embodiments with equivalent changes, but all the content that does not depart from the technical solution of the present invention, according to the technical content of the present invention Technical Essence Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

Claims (25)

1. A method for making an element with inductance, comprising the following steps: Wrapping a hollow coil with a magnetic glue to form a package; forming a first magnetic core body; and At least a part of the first magnetic core body is arranged in the hollow coil of the package body. 2. The method according to claim 1, wherein the first magnetic core body has a top, the top is connected to a column, at least a first part of the column is disposed in the hollow coil of the package and The top is disposed on the package body. 3. The method according to claim 2, further comprising the steps of: forming a second magnetic core body; and The cylinder is connected with the second magnetic core body. 4. The method of claim 3, wherein the second magnetic core body has an opening; a second portion of the cylinder is inserted into the opening to connect with the second magnetic core body. 5 . The method according to claim 1 , wherein the packaging body is injection-molded or compression-molded so that the magnetic material covers the pre-wound hollow coil. 6 . 6. A method for making a choke, comprising the following steps: Wrapping a hollow coil with a magnetic glue to form a package; forming a first magnetic core, the first magnetic core includes a center post and a top, the top is connected to one end of the center post; and At least a first portion of the center post is disposed in the hollow coil of the package, wherein the top is disposed on the package. 7. The method according to claim 6, further comprising the steps of: A second magnetic core body is formed, and the second magnetic core body has an opening, and a second part of the center column is disposed in the opening and engaged with the opening. 8. The method according to claim 7, wherein the second magnetic core body has a joint face and an assembly face opposite to the joint face, the end of the center post is adapted to be placed from the joint face into the opening, the opening is located at the center of the second magnetic core body and communicates with the joint surface and the assembly surface. 9. The method according to claim 8, wherein the hollow coil has two ends, and the two ends are arranged on the assembly surface, and the second magnetic core body also has two The wire grooves on the edge of the two magnetic cores, and the two ends pass through the two wire grooves. 10. The method according to claim 7, further comprising the step of forming a material layer, the material layer is disposed on the inner wall of the opening and located between the center pillar and the opening. 11 . The method according to claim 7 , wherein the second magnetic core body is a flat plate, wherein the second magnetic core body is formed by press molding and sintering, and has a magnetic permeability above 75. 12 . 12. A method for making a choke, comprising the following steps: form a shell; placing a hollow coil in the housing; placing a first magnetic core in the hollow coil; disposing a second magnetic core body in an opening of the housing and engaging with the opening; and A magnetic glue is arranged in the space between the casing and the hollow coil. 13. The method according to claim 12, wherein the first magnetic core body comprises a top plate and a center column, the top plate is connected to one end of the center column, the center column and the top plate are integrally formed, The hollow coil is located between the top plate of the first magnetic core body and the second magnetic core body. 14. The method according to claim 13, wherein the second magnetic core body has at least one injection hole located at the edge of the second magnetic core body, and the magnetic glue is filled in the housing through the injection hole and the space between the hollow coil. 15. The method according to claim 12, wherein the housing is made of metal or magnetic material. 16. An element with inductance, characterized in that the element with inductance has a plurality of outer surfaces, and the element with inductance comprises: a prewound hollow coil having two ends; and A magnetic body is disposed in the pre-wound hollow coil, wherein the two ends protrude from the plurality of outer surfaces, and the two ends serve as two pins of the element with inductance and are connected to an external circuit. 17. The element with inductance according to claim 16, wherein the two ends protrude from the same side of a first outer surface of the plurality of outer surfaces as two ends of the element with inductance pin. 18. The element with an inductor according to claim 16, wherein the two pins are two through-hole pins. 19. The component with an inductor according to claim 16, wherein the two pins are surface mount pins. 20. A choke, characterized in that it comprises: a prewound hollow coil having two ends; and A first magnetic core body is arranged in the pre-wound hollow coil; an encapsulation body for encapsulating the pre-wound hollow coil and the first magnetic core to form a plurality of outer surfaces of the choke, wherein the two ends protrude from the plurality of outer surfaces, Use as the two pins of the choke and connect to an external circuit. 21. The choke according to claim 20, wherein the first magnetic core body comprises a top plate and a central column, the top plate is connected to one end of the central column, and the central column is integrated with the top plate take shape. 22. The choke according to claim 21, further comprising a magnetic bottom plate, the hollow coil is located between the top plate of the first magnetic core body and the magnetic bottom plate, the center column and the magnetic bottom plate connected to form a core body. 23. The choke according to claim 20, wherein the two pins are two through-hole pins. 24. The choke as claimed in claim 22, wherein the magnetic bottom plate has an opening, wherein a part of the magnetic middle column is inserted into the opening and connected with the magnetic bottom plate. 25. The choke according to claim 22, wherein a surface of the bottom plate constitutes a first outer surface of the plurality of outer surfaces, wherein the bottom plate has two wire grooves located at the edge of the bottom plate, And the two ends respectively pass through the two wire slots to protrude from the same side of the first outer surface and serve as two pins of the choke.