Voice coil motor with magnetic field preserving structure

Abstract

This utility model discloses a voice coil motor with a magnetizing structure, including a housing assembly, an inner cavity containing a coil assembly and a magnetic circuit assembly, and a magnetizing structure on the magnetic circuit assembly for reducing magnetic leakage and increasing air gap magnetic flux density; the magnetic circuit assembly includes a stator yoke, and a permanent magnet shaft is inserted into the inner cavity of the stator yoke; the magnetizing structure is a magnetizing sleeve wrapped around the outer surface of the stator yoke, and the magnetizing sleeve has a ring-shaped structure; through the high permeability material and tight fit structure of the magnetizing sleeve, magnetic leakage is reduced and air gap magnetic flux density is increased, effectively improving the thrust density of the voice coil motor compared to traditional designs, meeting the high thrust requirements of miniaturized devices, and significantly improving magnetic performance; the interference fit of the protrusions and grooves and the high-strength insulating adhesive prevent the magnetizing sleeve from easily loosening, reducing the magnetic performance attenuation rate, enhancing structural reliability, and significantly extending the service life of the voice coil motor.

Description

Technical Field

[0001] This utility model relates to the field of voice coil motor technology, and in particular to a voice coil motor with a magnetizing structure. Background Technology

[0002] A voice coil motor is a device that converts electrical energy into mechanical energy and enables linear motion with a limited swing angle.

[0003] Voice coil motors are widely used in applications such as camera autofocus and precision positioning. During the operation of a voice coil motor, magnetic leakage in the magnetic circuit system can affect the air gap magnetic flux density, thereby reducing the motor's thrust and operating efficiency. Existing voice coil motors lack effective magnetic preservation structures to optimize magnetic circuit performance.

[0004] To address this, a voice coil motor with a magnetizing structure is proposed. Utility Model Content

[0005] The purpose of this invention is to provide a voice coil motor with a magnetizing structure to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the main technical solutions adopted by this utility model include:

[0007] A voice coil motor with a magnetizing structure includes:

[0008] The housing assembly has an inner cavity housing a coil assembly and a magnetic circuit assembly. The magnetic circuit assembly has a magnetically protective structure for reducing magnetic leakage and increasing air gap magnetic flux density, wherein:

[0009] The magnetic circuit assembly includes a stator yoke, and a permanent magnet shaft is inserted into the inner cavity of the stator yoke;

[0010] The magnetic protection structure is a magnetic protection sleeve wrapped around the outer surface of the stator yoke, and the magnetic protection sleeve has a ring-shaped structure.

[0011] As a preferred technical solution, the magnetic retaining sleeve is tightly fitted to the outer peripheral wall of the stator yoke and is made of SECC or SPCC material.

[0012] As a preferred technical solution, the housing assembly includes an upper cover and a lower base, the upper cover being fastened to the top of the lower base, and the upper cover and the lower base cooperating to fix the coil assembly.

[0013] As a preferred technical solution, the inner wall surface of the magnetic retaining sleeve is integrally formed with several protruding ridges, and the several protruding ridges are distributed at equal angles along the circumference of the magnetic retaining sleeve. The surface of the stator magnetic yoke is provided with a groove that matches the protruding ridges, and the groove and the corresponding protruding ridge are interference fit.

[0014] As a preferred technical solution, the cross-section of the protrusion and the groove is semi-cylindrical with a radius of 0.05 to 0.15 mm and a manufacturing tolerance of ±0.01 mm. The interface between the protrusion and the groove is filled with epoxy resin insulating adhesive.

[0015] As a preferred technical solution, the absolute value of the difference between the axial length of the magnetic retaining sleeve and the axial length of the stator yoke is ≤0.1mm, and the protrusions and grooves extend along the axial direction of the magnetic retaining sleeve and the stator yoke to their respective end faces.

[0016] As a preferred technical solution, the coil assembly includes an insulating wire frame embedded in the inner cavity of the lower seat, the top end of the insulating wire frame extending through the inner cavity of the upper cover, and two coils are placed sequentially from top to bottom in the inner cavity of the insulating wire frame. Each coil has a stator yoke nested inside it, and a magnetic retaining sleeve is fitted on the outer surface of each stator yoke.

[0017] As a preferred technical solution, a washer is fixedly connected to the middle of the inner cavity of the insulating wire frame, and the washer is located between the two coils.

[0018] As a preferred technical solution, the inner cavity of the washer is provided with a moving iron core, the moving iron core is slidably engaged with the inner cavity of the washer, the two stator yokes are respectively located at the top and bottom of the moving iron core, the top and bottom of the insulating wire frame are fixedly connected with elastic metal sheets, and the end of the permanent magnet shaft away from the moving iron core is fixedly connected to the elastic metal sheet.

[0019] This utility model has at least the following beneficial effects:

[0020] This application utilizes a high-permeability material and a tightly fitted structure in the magnetic sleeve to reduce magnetic leakage and increase air gap magnetic flux density. Compared to traditional designs, this effectively improves the thrust density of the voice coil motor, meeting the high thrust requirements of miniaturized devices and significantly enhancing magnetic performance. The interference fit of the protrusions and grooves, along with high-strength insulating adhesive, prevents the magnetic sleeve from easily loosening, reducing magnetic performance attenuation, enhancing structural reliability, and significantly extending the lifespan of the voice coil motor. The low magnetic leakage design reduces interference to surrounding electronic components, making it suitable for scenarios with high electromagnetic compatibility requirements, such as mobile phone cameras and precision instrument platforms. Furthermore, the dual-coil structure allows for flexible adaptation to different load requirements, improving product versatility. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model;

[0022] Figure 2 This is an exploded view of the structure of this utility model;

[0023] Figure 3 This is a cross-sectional view of the structure of this utility model;

[0024] Figure 4 This is an exploded view of the structure of the coil, magnetic circuit assembly and magnetic retaining sleeve of this utility model;

[0025] Figure 5 This is an exploded view of the stator yoke and magnetic retaining sleeve of this utility model.

[0026] In the diagram: 100, outer casing assembly; 110, top cover; 120, lower base; 200, coil assembly; 210, insulating wire frame; 220, coil; 230, washer; 300, magnetic circuit assembly; 310, stator yoke; 311, groove; 320, permanent magnet shaft; 330, mover core; 340, elastic metal sheet; 400, magnetic retaining sleeve; 410, raised ridge. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Please see Figures 1-5 This utility model provides a voice coil motor with a magnetizing structure, including a housing assembly 100, a coil assembly 200, a magnetic circuit assembly 300, and a magnetizing structure for reducing magnetic leakage and increasing air gap magnetic flux density. The coil assembly 200, the magnetic circuit assembly 300, and the magnetizing structure are all located in the inner cavity of the housing assembly 100, and the magnetizing structure is located on the magnetic circuit assembly 300. The magnetic circuit assembly 300 includes a stator yoke 310, and a permanent magnet shaft 320 is inserted into the inner cavity of the stator yoke 310. The magnetizing structure is a magnetizing sleeve 400 wrapped around the outer surface of the stator yoke 310, and the magnetizing sleeve 400 has a ring-shaped structure. By wrapping the stator yoke 310 with the ring-shaped magnetizing sleeve 400, a closed magnetic shielding path is formed, reducing the magnetic leakage of the magnetic circuit assembly 300, increasing the air gap magnetic flux density, and thus increasing the thrust of the voice coil motor to meet the power requirements of precision drive scenarios.

[0029] The magnetic sleeve 400 is tightly fitted to the outer peripheral wall of the stator yoke 310 and is made of SECC or SPCC material. SECC or SPCC material has high permeability and low magnetic reluctance characteristics. Tightly fitting the stator yoke 310 can reduce magnetic reluctance abrupt changes and reduce hysteresis loss. The oxidation resistance of the material can extend the service life of the voice coil motor in humid environments.

[0030] The housing assembly 100 includes an upper cover 110 and a lower base 120. The upper cover 110 is fastened to the top of the lower base 120, and the upper cover 110 and the lower base 120 cooperate to fix the coil assembly 200. The upper cover 110 and the lower base 120 fasten together to form a rigid frame, which can ensure the axial positioning accuracy of the coil assembly 200, avoid uneven air gap caused by coil 220 offset, and ensure thrust fluctuation during motor operation.

[0031] The inner wall of the magnetic sleeve 400 is integrally formed with several protruding ridges 410, which are distributed at equal angles along the circumference of the magnetic sleeve 400. The surface of the stator yoke 310 is provided with grooves 311 that are adapted to the protruding ridges 410. The grooves 311 and the corresponding protruding ridges 410 are interference fit. The circumferentially distributed protruding ridges 410 and the grooves 311 form a multi-support positioning, so that the radial fit tolerance between the magnetic sleeve 400 and the stator yoke 310 is controlled within ±0.01mm, preventing the magnetic sleeve 310 from rotating and misaligning, ensuring the uniformity of magnetic shielding, and helping to improve the stability of magnetic leakage reduction effect.

[0032] The cross-sections of the protruding rib 410 and the groove 311 are semi-cylindrical with a radius of 0.05 to 0.15 mm and a manufacturing tolerance of ±0.01 mm. The interface between the protruding rib 410 and the groove 311 is filled with epoxy resin insulating adhesive, and the shear strength of the insulating adhesive after curing is ≥5 MPa. The interference fit between the semi-cylindrical protruding rib 410 and the groove 311, combined with the epoxy resin insulating adhesive, increases the axial tensile strength of the magnetic sleeve 400, preventing structural loosening under vibration. The insulating adhesive also serves as a magnetic shielding gap filler, further reducing magnetic leakage.

[0033] The absolute value of the difference between the axial length of the magnetic sleeve 400 and the axial length of the stator yoke 310 is ≤0.1mm. The protrusion 410 and the groove 311 extend along the axial direction of the magnetic sleeve 400 and the stator yoke 310 to their respective end faces. The difference in axial length between the magnetic sleeve 400 and the stator yoke 310 is ≤0.1mm, ensuring full coverage of the magnetic shielding area and avoiding axial magnetic leakage. The protrusion 400 and the groove 311 extend to the end faces, forming a continuous magnetic shielding path, thereby reducing axial magnetic resistance.

[0034] The coil assembly 200 includes an insulating wire frame 210 embedded in the inner cavity of the lower base 120. The top of the insulating wire frame 210 extends into the inner cavity of the upper cover 110. Two coils 220 are placed sequentially from top to bottom in the inner cavity of the insulating wire frame 210. Each coil 220 has a stator yoke 310 nested inside it. A magnetic retaining sleeve 400 is fitted on the outer surface of each stator yoke 310. The design of the upper and lower double coils 220 nested with double stator yokes 310 makes the voice coil motor form a symmetrical magnetic circuit, which is improved compared to the single coil structure. At the same time, it cancels the radial electromagnetic force and reduces the operating noise, making it suitable for high-precision scenarios such as camera autofocus.

[0035] Among them, a washer 230 is fixedly connected in the middle of the inner cavity of the insulating wire frame 210. The washer 230 is located between the two coils 220. The washer 230 is fixed between the two coils 220 to ensure the axial spacing accuracy of the coils 220 and to ensure the uniformity of the air gap.

[0036] The inner cavity of the washer 230 is provided with a moving iron core 330, which slides in conjunction with the inner cavity of the washer 230. Two stator yokes 310 are located at the top and bottom of the moving iron core 330, respectively. Elastic metal sheets 340 are fixedly connected to the top and bottom of the insulating wire frame 210. The end of the permanent magnet shaft 320 away from the moving iron core 330 is fixedly connected to the elastic metal sheet 340. The sliding contact between the moving iron core 330 and the washer 230 enables linear motion, and the elastic metal sheet 340 provides a restoring force. The permanent magnet shaft 320 is fixed by the elastic metal sheet 340, which buffers vibration and impact and improves structural reliability.

[0037] The working principle of this utility model is as follows:

[0038] When current flows through coil assembly 200, according to Ampere's law, coil 220 generates a toroidal magnetic field. This magnetic field interacts with the constant magnetic field of permanent magnet shaft 320 in the air gap, generating Ampere force. Under the action of Ampere force, mover core 330 moves axially, driving loads such as camera lenses to achieve precise positioning. Elastic metal sheet 340 provides a restoring elastic force, forming a reciprocating motion mechanism.

[0039] The magnetic sleeve 400 is made of a high magnetic permeability material, forming a low magnetic resistance circuit. It guides the leakage magnetic flux through the magnetic sleeve closure, rather than leaking into the external space, thereby improving the concentration of air gap magnetic flux density.

[0040] The interference fit between the protruding ridge 410 and the groove 311, along with the filling of insulating glue, eliminates the air gap between the magnetic sleeve 400 and the stator yoke 310, avoids the loss of magnetic flux at the interface, and ensures the continuity of the magnetic circuit.

[0041] The symmetrical arrangement of the double coil 220 and the double stator yoke 310 makes the magnetic field distribution uniform, counteracts the radial magnetic pull, reduces the sway of the mover core 330 during movement, and improves the stability of movement.

[0042] All parts not described in this utility model are the same as or can be implemented using existing technology. Although embodiments of this utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this utility model, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A voice coil motor having a magnetic structure, characterized by, include: The housing assembly (100) has an inner cavity containing a coil assembly (200) and a magnetic circuit assembly (300). The magnetic circuit assembly (300) is provided with a magnetic preservation structure for reducing magnetic leakage and increasing air gap magnetic flux density, wherein: The magnetic circuit assembly (300) includes a stator yoke (310), and a permanent magnet shaft (320) is inserted into the cavity of the stator yoke (310). The magnetic protection structure is a magnetic protection sleeve (400) wrapped around the outer surface of the stator yoke (310), and the magnetic protection sleeve (400) has a ring-shaped structure.

2. The voice coil motor with a magnetic field preserving structure according to claim 1, wherein: The magnetic sleeve (400) is tightly fitted to the outer peripheral wall of the stator yoke (310) and is made of SECC or SPCC material.

3. The voice coil motor with a magnetic field preserving structure according to claim 2, wherein: The housing assembly (100) includes an upper cover (110) and a lower seat (120), the upper cover (110) being fastened to the top of the lower seat (120), and the upper cover (110) and the lower seat (120) cooperating to fix the coil assembly (200).

4. The voice coil motor with a magnetic field preserving structure according to claim 3, wherein: The inner wall of the magnetic sleeve (400) is integrally formed with a number of protruding ridges (410). The number of protruding ridges (410) are distributed at equal angles along the circumference of the magnetic sleeve (400). The surface of the stator yoke (310) is provided with a groove (311) that matches the protruding ridges (410). The groove (311) is interference-fitted with the corresponding protruding ridge (410).

5. The voice coil motor with a magnetizing structure according to claim 4, characterized in that: The cross-section of the protruding ridge (410) and the groove (311) is semi-cylindrical with a radius of 0.05 to 0.15 mm and a manufacturing tolerance of ±0.01 mm. The interface between the protruding ridge (410) and the groove (311) is filled with epoxy resin insulating adhesive.

6. The voice coil motor with a magnetic field preserving structure of claim 5, wherein: The absolute value of the difference between the axial length of the magnetic sleeve (400) and the axial length of the stator yoke (310) is ≤0.1mm, and the protrusion (410) and groove (311) extend along the axial direction of the magnetic sleeve (400) and the stator yoke (310) to their respective end faces.

7. The voice coil motor with a magnetic field preserving structure of claim 6, wherein: The coil assembly (200) includes an insulating wire frame (210) embedded in the inner cavity of the lower seat (120). The top of the insulating wire frame (210) extends through the inner cavity of the upper cover (110). Two coils (220) are placed in the inner cavity of the insulating wire frame (210) from top to bottom. Each coil (220) has a stator yoke (310) nested inside it. A magnetic sleeve (400) is fitted on the outer surface of each stator yoke (310).

8. The voice coil motor with a magnetic field preserving structure of claim 7, wherein: A washer (230) is fixedly connected to the middle of the inner cavity of the insulating wire frame (210), and the washer (230) is located between the two coils (220).

9. The voice coil motor with a magnetizing structure according to claim 8, characterized in that: The inner cavity of the washer (230) is provided with a moving iron core (330), the moving iron core (330) and the inner cavity of the washer (230) are slidably engaged, the two stator yokes (310) are respectively located at the top and bottom of the moving iron core (330), the top and bottom of the insulating wire frame (210) are fixedly connected with elastic metal sheets (340), and the end of the permanent magnet shaft (320) away from the moving iron core (330) is fixedly connected to the elastic metal sheet (340).

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