High-thrust-density voice coil motor with auxiliary enhanced magnetic circuit

Abstract

The invention discloses a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit, which comprises a stator assembly and a rotor assembly, and is characterized in that the stator assembly comprises a magnet yoke part, a basic magnetic circuit and a first auxiliary magnetic circuit; the basic magnetic circuit comprises a plurality of radially magnetized first inner ring permanent magnets and first outer ring permanent magnets, the first inner ring permanent magnets sleeve the second magnet yoke at intervals, and the first outer ring permanent magnets are arranged on the inner wall of the first magnet yoke at intervals; the first auxiliary magnetic circuit comprises a plurality of axially magnetized second inner ring permanent magnets and second outer ring permanent magnets, each second inner ring permanent magnet is alternately embedded between two adjacent first inner ring permanent magnets, and each second outer ring permanent magnet is alternately embedded between two adjacent first outer ring permanent magnets. The voice coil motor is applied to the field of motors, the magnetic flux density of the working air gap where the coil is located is improved, magnetic flux density fluctuation can be reduced, and therefore the output force size and stability of the voice coil motor are improved.

Description

Technical Field

[0001] The invention relates to the technical field of motors, in particular to a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit. Background Art

[0002] Voice coil motor (VCM) is a DC drive motor that achieves high-speed reciprocating motion within a short stroke. It has the advantages of large thrust, fast response, high precision, and easy control. It is widely used in the field of active vibration control. Traditionally, the purpose of increasing thrust or reducing thrust fluctuation is achieved by changing the permanent magnet array form and increasing the number of coil groups. However, due to the inherent end effect of the permanent magnet itself, it is inevitable to cause a conflict between the effective stroke of the mover, the thrust size, and the thrust fluctuation. Therefore, under the conditions of volume constraints and the determination of the effective stroke, optimizing the magnetic circuit design to improve the utilization rate of the air gap magnetic flux, thereby improving the thrust density of the voice coil motor and reducing the thrust fluctuation has become a major problem faced by the academic and engineering communities. Summary of the invention

[0003] In view of the deficiencies in the above-mentioned prior art, the present invention provides a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit, which not only has a simple structure, but also can increase the magnetic flux density of the working air gap where the coil is located, and help to reduce the magnetic flux density fluctuation, thereby improving the output force and stability of the voice coil motor.

[0004] To achieve the above object, the present invention provides a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit, comprising a stator assembly and a mover assembly, wherein the stator assembly comprises a yoke portion, a basic magnetic circuit and a first auxiliary magnetic circuit, and the mover assembly comprises a winding skeleton, a first coil and a second coil;

[0005] The yoke part includes a first yoke and a second yoke, the first yoke is a cylindrical structure with one end open, and the second yoke is coaxially arranged in the first yoke;

[0006] The basic magnetic circuit includes a plurality of radially magnetized and axially flush first inner ring permanent magnets and first outer ring permanent magnets, each of the first inner ring permanent magnets is axially spaced and sleeved on the second magnetic yoke, and each of the first outer ring permanent magnets is axially spaced and arranged on the inner wall of the first magnetic yoke;

[0007] The first auxiliary magnetic circuit includes a plurality of axially magnetized and axially flush second inner ring permanent magnets and second outer ring permanent magnets, each of the second inner ring permanent magnets is alternately embedded in the gap between two adjacent first inner ring permanent magnets and the bottom first inner ring permanent magnet and the bottom wall of the first magnetic yoke, and each of the second outer ring permanent magnets is alternately embedded in the gap between two adjacent first outer ring permanent magnets and the bottom first outer ring permanent magnet and the bottom wall of the first magnetic yoke, so as to improve the thrust density of the voice coil motor;

[0008] An air gap is formed between the first inner ring permanent magnet, the first outer ring permanent magnet, the second inner ring permanent magnet, and the second outer ring permanent magnet. The winding frame is arranged in the air gap. The first coil and the second coil are arranged on the winding frame at axial intervals, and the winding directions of the first coil and the second coil are opposite.

[0009] In one of the embodiments, the stator assembly further includes a second auxiliary magnetic circuit, which is disposed on the second magnetic yoke to reshape the air gap magnetic field of the voice coil motor and reduce thrust fluctuations without reducing thrust density.

[0010] In one embodiment, the second auxiliary magnetic circuit includes a first cylindrical permanent magnet and a second cylindrical permanent magnet that are axially magnetized;

[0011] The first cylindrical permanent magnet is embedded in the second magnetic yoke, or the first cylindrical permanent magnet is located between the bottom of the second magnetic yoke and the first magnetic yoke, and the bottom end of the first cylindrical permanent magnet is flush with the top ends of the first inner ring permanent magnet and the first outer ring permanent magnet at the bottom;

[0012] The second cylindrical permanent magnet is embedded in the second yoke, and the second cylindrical permanent magnet is located above the first cylindrical permanent magnet.

[0013] In one embodiment, the first inner ring permanent magnet, the first outer ring permanent magnet, the second inner ring permanent magnet, the second outer ring permanent magnet, the first cylindrical permanent magnet, and the second cylindrical permanent magnet are made of permanent magnetic materials, including but not limited to aluminum-nickel-cobalt permanent magnetic materials, neodymium-iron-boron permanent magnetic materials, iron-chromium-cobalt permanent magnetic materials, ferrite permanent magnetic materials, rare earth permanent magnetic materials, or composite permanent magnetic materials.

[0014] In one embodiment, the winding frame, the first coil, and the second coil are fixed by pouring resin.

[0015] In one embodiment, the first magnetic yoke and the second magnetic yoke are made of metal soft magnetic material or ferrite soft magnetic material.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] The present invention optimizes the magnetic circuit design of the stator assembly, adopts a bipolar basic magnetic circuit to improve the utilization rate of the permanent magnet and the magnetic yoke, and further concentrates and uniformizes the air gap flux distribution by adding an auxiliary magnetic circuit, thereby achieving high thrust density and low thrust fluctuation of the voice coil motor. The present invention has a simple structure, low cost, and convenient installation. It can improve the thrust density of the motor and reduce the thrust fluctuation without increasing the total volume of the voice coil motor, thereby achieving precise control of the voice coil motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the surface structure of a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit in an embodiment of the present invention;

[0020] Figure 2 Result diagram of the air gap magnetic flux density characteristic curve of the voice coil motor in the embodiment of the present invention;

[0021] Figure 3 This is a result diagram of the output thrust characteristic curve within the travel range of the voice coil motor in an embodiment of the present invention.

[0022] Figure numbers: yoke part 1, first yoke 101, second yoke 102, basic magnetic circuit 2, first inner ring permanent magnet 201, first outer ring permanent magnet 202, first auxiliary magnetic circuit 3, second inner ring permanent magnet 301, second outer ring permanent magnet 302, winding skeleton 4, first coil 5, second coil 6, second auxiliary magnetic circuit 7, first cylindrical permanent magnet 701, second cylindrical permanent magnet 702.

[0023] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] 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.

[0025] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] like Figure 1 As shown in the present embodiment, a high thrust density voice coil motor with an auxiliary enhanced magnetic circuit is disclosed, which mainly includes a stator assembly and a mover assembly. The stator assembly includes a yoke part 1, a basic magnetic circuit 2 and a first auxiliary magnetic circuit 3, and the mover assembly includes a winding skeleton 4, a first coil 5 and a second coil 6.

[0030] In this embodiment, the yoke part 1 includes a first yoke 101 and a second yoke 102, the first yoke 101 is a circular cylindrical structure with one end open, the second yoke 102 is coaxially arranged on the inner bottom wall of the first yoke 101, and the outer wall of the second yoke 102 and the inner wall of the first yoke 101 form a cavity capable of accommodating the basic magnetic circuit 2, the first auxiliary magnetic circuit 3 and the mover assembly. Among them, both the first yoke 101 and the second yoke 102 can be made of metal soft magnetic material or ferrite soft magnetic material. For example, metal soft magnetic materials such as electrical pure iron, silicon steel, permalloy, iron-aluminum alloy, iron-silicon-aluminum alloy, iron-cobalt alloy, amorphous soft magnetic material, nanocrystalline soft magnetic material, soft magnetic composite material, etc. can be used, and ferrite soft magnetic materials such as manganese-zinc ferrite and nickel-zinc ferrite can also be used.

[0031] In this embodiment, the basic magnetic circuit 2 includes a plurality of radially magnetized and axially flush first inner ring permanent magnets 201 and first outer ring permanent magnets 202. Specifically, each first inner ring permanent magnet 201 is axially spaced and sleeved on the second magnetic yoke 102, and there is a gap between the bottom end of the lowest first inner ring permanent magnet 201 and the bottom inner wall of the first magnetic yoke 101, and the top end of the highest first inner ring permanent magnet 201 is flush with the top ends of the first magnetic yoke 101 and the second magnetic yoke 102. Each first outer ring permanent magnet 202 is axially spaced on the inner wall of the first magnetic yoke 101, and similarly, there is a gap between the bottom end of the lowest first outer ring permanent magnet 202 and the bottom inner wall of the first magnetic yoke 101, and the top end of the highest first outer ring permanent magnet 202 is flush with the top ends of the first magnetic yoke 101 and the second magnetic yoke 102. The first inner ring permanent magnet 201 and the first outer ring permanent magnet 202 at the same height are magnetized in the same radial direction, and the two first outer ring permanent magnets 202 and the two first inner ring permanent magnets 201 connected in the axial direction are magnetized in opposite radial directions.

[0032] In this embodiment, the first auxiliary magnetic circuit 3 includes a plurality of axially magnetized and axially flush second inner ring permanent magnets 301 and second outer ring permanent magnets 302. Specifically, each second inner ring permanent magnet 301 is axially spaced and sleeved on the second magnetic yoke 102, and each second inner ring permanent magnet 301 is alternately embedded in the gap between two adjacent first inner ring permanent magnets 201 and between the bottom first inner ring permanent magnet 201 and the bottom wall of the first magnetic yoke 101. Similarly, each second outer ring permanent magnet 302 is axially spaced and arranged on the inner wall of the first magnetic yoke 101, and each second outer ring permanent magnet 302 is alternately embedded in the gap between two adjacent first outer ring permanent magnets 202 and between the bottom first outer ring permanent magnet 202 and the bottom wall of the first magnetic yoke 101. Among them, the second inner ring permanent magnet 301 and the second outer ring permanent magnet 302 at the same height are axially magnetized in opposite directions, the two adjacent second inner ring permanent magnets 301 are axially magnetized in opposite directions, and the two adjacent second outer ring permanent magnets 302 are axially magnetized in opposite directions.

[0033] In this embodiment, an air gap is formed between the first inner ring permanent magnet 201, the first outer ring permanent magnet 202, the second inner ring permanent magnet 301, and the second outer ring permanent magnet 302, the winding skeleton 4 is arranged in the air gap, the first coil 5 and the second coil 6 are arranged on the winding skeleton 4 at intervals along the axial direction, and the winding directions of the first coil 5 and the second coil 6 are opposite. Specifically, the first coil 5 can be set as a long coil, and the second coil 6 can be set as a short coil, and the first coil 5 is located on the winding skeleton 4 and close to the opening of the first magnetic yoke 101, and the second coil 6 is located on the winding skeleton 4 and close to the bottom wall of the first magnetic yoke 101, and the number of turns and the winding length of the first coil 5 and the second coil 6 can be designed and determined according to the requirements. In the specific implementation process, the winding skeleton 4, the first coil 5, and the second coil 6 are fixedly connected by pouring epoxy resin to form a movable subassembly.

[0034] As a preferred embodiment, the stator assembly further includes a second auxiliary magnetic circuit 7, which is arranged on the second magnetic yoke 102 to reshape the air gap magnetic field of the voice coil motor and reduce thrust fluctuations without reducing thrust density. Specifically, the second auxiliary magnetic circuit 7 includes an axially magnetized first cylindrical permanent magnet 701 and a second cylindrical permanent magnet 702, the first cylindrical permanent magnet 701 is embedded in the second magnetic yoke 102, or the first cylindrical permanent magnet 701 is located between the bottom of the second magnetic yoke 102 and the first magnetic yoke 101, and the bottom end of the first cylindrical permanent magnet 701 is flush with the top of the first inner ring permanent magnet 201 and the first outer ring permanent magnet 202 at the bottom, the second cylindrical permanent magnet 702 is embedded in the second magnetic yoke 102, and the second cylindrical permanent magnet 702 is located above the first cylindrical permanent magnet 701, that is, the first cylindrical permanent magnet 701 and the second cylindrical permanent magnet 702 separate the second magnetic yoke 102 into multiple parts.

[0035] In the specific implementation process, the first inner ring permanent magnet 201, the first outer ring permanent magnet 202, the second inner ring permanent magnet 301, the second outer ring permanent magnet 302, the first cylindrical permanent magnet 701, and the second cylindrical permanent magnet 702 are made of permanent magnetic materials, for example, aluminum-nickel-cobalt permanent magnetic materials, neodymium-iron-boron permanent magnetic materials, iron-chromium-cobalt permanent magnetic materials, ferrite permanent magnetic materials, rare earth permanent magnetic materials or composite permanent magnetic materials can be used.

[0036] The working principle of the voice coil motor in this embodiment is:

[0037] When the first coil 5 and the second coil 6 of the mover assembly located in the air gap magnetic field are energized, they are subjected to the Ampere force and produce linear motion, and the movement speed and direction of the mover assembly are controlled by controlling the current; since the traditional monopole permanent magnet array generates a magnetic field in the air gap of the voice coil motor and there is an end effect, the magnetic induction intensity at both ends of the permanent magnet in the air gap is much lower than the magnetic induction intensity in the middle. For this reason, in this embodiment, a bipolar permanent magnet array composed of a first inner ring permanent magnet 201 and a first outer ring permanent magnet 202 is designed. The basic magnetic circuit 2 constituted compensates for the leakage magnetic flux at the end of the voice coil motor and reduces the uneven distribution of the air gap magnetic flux of the voice coil motor. At the same time, in order to allow more magnetic flux to pass through the working air gap of the voice coil motor, obtain a higher thrust density, and reduce the leakage magnetic resistance of the upper half of the magnetic circuit in the basic magnetic circuit 2, a first auxiliary magnetic circuit 3 composed of a second inner ring permanent magnet 301 and a second outer ring permanent magnet 302 is designed. It can not only compensate for the end leakage magnetic flux of the permanent magnet in the basic magnetic circuit 2, but also increase the air gap magnetic flux of the basic magnetic circuit 2 by reducing the saturation of the magnetic yoke. The magnetic flux of the upper half of the magnetic circuit will increase. After adding the first auxiliary magnetic circuit 3, the magnetic flux in the lower half of the magnetic circuit will decrease, thereby making the magnetic flux density distribution in the magnetic yoke more uniform. At the same time, the magnetic saturation in the middle and bottom will also be reduced, so that the air gap can have a larger magnetic flux. Taking into account that after adding the first auxiliary magnetic circuit 3, the magnetic concentration effect of the axial permanent magnet may cause local magnetic flux concentration, resulting in uneven distribution of magnetic flux density in the air gap, the second auxiliary magnetic circuit 7 is further designed in this embodiment to compensate for the deficiency of weakening of the air gap magnetic flux due to the introduction of the first auxiliary magnetic circuit 3, so as to reduce thrust fluctuations and realize precise and smooth motion control of the voice coil motor.

[0038] The high thrust density voice coil motor with an auxiliary enhanced magnetic circuit in this embodiment is further described below with reference to specific examples.

[0039] In this example, the number of the first inner ring permanent magnet 201, the first outer ring permanent magnet 202, the second inner ring permanent magnet 301, and the second outer ring permanent magnet 302 are all two. Figure 1As shown. The first inner ring permanent magnet 201 and the first outer ring permanent magnet 202 located at the top are 5.7 mm high and are magnetized in the radially inward direction. The first inner ring permanent magnet 201 and the first outer ring permanent magnet 202 located at the bottom are 16 mm high and are magnetized in the radially outward direction. The second inner ring permanent magnet 301 and the second outer ring permanent magnet 302 located at the top are 7.5 mm high, wherein the second inner ring permanent magnet 301 is magnetized in the negative direction of the y-axis, and the second outer ring permanent magnet 302 is magnetized in the positive direction of the y-axis. The second inner ring permanent magnet 301 and the second outer ring permanent magnet 302 located at the bottom are 1 mm high, wherein the second inner ring permanent magnet 301 is magnetized in the positive direction of the y-axis, and the second outer ring permanent magnet 302 is magnetized in the negative direction of the y-axis. The height of the first cylindrical permanent magnet 701 and the second cylindrical permanent magnet 702 are both 2 mm, wherein the first cylindrical permanent magnet 701 is magnetized along the positive direction of the y-axis, and the second cylindrical permanent magnet 702 is magnetized along the negative direction of the y-axis. The height of the portion of the second yoke 102 located above the second cylindrical permanent magnet 702 is 18.2 mm, the height of the portion of the second yoke 102 located between the first cylindrical permanent magnet 701 and the second cylindrical permanent magnet 702 is 7 mm, and the height of the first yoke 101 is 32.2 mm. The first inner ring permanent magnet 201, the first outer ring permanent magnet 202, the second inner ring permanent magnet 301, the second outer ring permanent magnet 302, the first cylindrical permanent magnet 701, and the second cylindrical permanent magnet 702 are all made of neodymium iron boron permanent magnet material, with a grade of N45SH. The first yoke 101 and the second yoke 102 are both made of soft iron and soft magnetic material. The coil length of the first coil 5 is 13.2 mm, and the length of the second coil 6 is 8.5 mm.

[0040] The air gap magnetic flux density characteristic curves of three voice coil motors are obtained through COMSOL finite element simulation, such as Figure 2 As shown, the air gap magnetic density of the traditional monopole permanent magnet array voice coil motor is small in the entire air gap length range, and the effective working air gap magnetic density is only 0.2T, while the air gap magnetic density of the voice coil motor with the first auxiliary magnetic circuit 3 is greatly improved in the entire air gap length range, and the air gap magnetic density is increased to 0.63T at most, especially in the upper half of the air gap, the air gap magnetic density is evenly increased. The improved dual auxiliary magnetic circuit array voice coil motor (i.e., the voice coil motor with the first auxiliary magnetic circuit 3 and the second auxiliary magnetic circuit 7) proposed in this embodiment not only has a greatly improved air gap magnetic density, but also has a smaller fluctuation of the air gap magnetic density in the upper half of the stroke compared to the voice coil motor with only the first auxiliary magnetic circuit 3, which is conducive to improving the thrust stability of the motor.

[0041] like Figure 3As shown, the thrust characteristic curves of the three voice coil motors in the entire effective stroke are as follows: the average thrust of the traditional monopole permanent magnet array voice coil motor is 8.46N, the maximum thrust is 8.76N, and the thrust fluctuation rate is 6.2%; the voice coil motor with the first auxiliary magnetic circuit 3 has an average thrust of 9.99N, a maximum thrust of 10.34N, and a thrust fluctuation rate of 7.0%. Compared with the traditional magnetic circuit motor, the thrust is improved, but the thrust fluctuation is increased; the voice coil motor with the first auxiliary magnetic circuit 3 and the second auxiliary magnetic circuit 7 reduces the end magnetic leakage, significantly increases the thrust of the end, and reduces the thrust fluctuation. The average thrust is 10.15N, the maximum thrust is 10.5N, and the thrust fluctuation rate is 6.0%.

[0042] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A high thrust density voice coil motor with an auxiliary enhanced magnetic circuit, characterized in that: It includes a stator assembly and a mover assembly, wherein the stator assembly includes a yoke part, a basic magnetic circuit and a first auxiliary magnetic circuit, and the mover assembly includes a winding skeleton, a first coil and a second coil; The yoke part includes a first yoke and a second yoke, the first yoke is a cylindrical structure with one end open, and the second yoke is coaxially arranged in the first yoke; The basic magnetic circuit includes a plurality of radially magnetized and axially flush first inner ring permanent magnets and first outer ring permanent magnets, each of the first inner ring permanent magnets is axially spaced and sleeved on the second magnetic yoke, and each of the first outer ring permanent magnets is axially spaced and arranged on the inner wall of the first magnetic yoke; The first auxiliary magnetic circuit includes a plurality of axially magnetized and axially flush second inner ring permanent magnets and second outer ring permanent magnets, each of the second inner ring permanent magnets is alternately embedded in the gap between two adjacent first inner ring permanent magnets and the bottom first inner ring permanent magnet and the bottom wall of the first magnetic yoke, and each of the second outer ring permanent magnets is alternately embedded in the gap between two adjacent first outer ring permanent magnets and the bottom first outer ring permanent magnet and the bottom wall of the first magnetic yoke, so as to improve the thrust density of the voice coil motor; An air gap is formed between the first inner ring permanent magnet, the first outer ring permanent magnet, the second inner ring permanent magnet, and the second outer ring permanent magnet. The winding frame is arranged in the air gap. The first coil and the second coil are arranged on the winding frame at axial intervals, and the winding directions of the first coil and the second coil are opposite.

2. The high thrust density voice coil motor with auxiliary enhanced magnetic circuit according to claim 1, characterized in that: The stator assembly also includes a second auxiliary magnetic circuit, which is arranged on the second magnetic yoke to reshape the air gap magnetic field of the voice coil motor and reduce thrust fluctuations without reducing thrust density.

3. The high thrust density voice coil motor with auxiliary enhanced magnetic circuit according to claim 2, characterized in that: The second auxiliary magnetic circuit includes a first cylindrical permanent magnet and a second cylindrical permanent magnet which are axially magnetized; The first cylindrical permanent magnet is embedded in the second magnetic yoke, or the first cylindrical permanent magnet is located between the bottom of the second magnetic yoke and the first magnetic yoke, and the bottom end of the first cylindrical permanent magnet is flush with the top ends of the first inner ring permanent magnet and the first outer ring permanent magnet at the bottom; The second cylindrical permanent magnet is embedded in the second yoke, and the second cylindrical permanent magnet is located above the first cylindrical permanent magnet.

4. The high thrust density voice coil motor with auxiliary enhanced magnetic circuit according to claim 3, characterized in that: The first inner ring permanent magnet, the first outer ring permanent magnet, the second inner ring permanent magnet, the second outer ring permanent magnet, the first cylindrical permanent magnet, and the second cylindrical permanent magnet are made of permanent magnetic materials, including but not limited to aluminum-nickel-cobalt permanent magnetic materials, neodymium-iron-boron permanent magnetic materials, iron-chromium-cobalt permanent magnetic materials, ferrite permanent magnetic materials, rare earth permanent magnetic materials, or composite permanent magnetic materials.

5. The high thrust density voice coil motor with auxiliary enhanced magnetic circuit according to any one of claims 1 to 4, characterized in that: The winding frame, the first coil and the second coil are fixed by pouring resin.

6. The high thrust density voice coil motor with auxiliary enhanced magnetic circuit according to any one of claims 1 to 4, characterized in that: The first magnetic yoke and the second magnetic yoke are made of metal soft magnetic material or ferrite soft magnetic material.

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