A voice coil motor with a magnetic gravity compensation structure

Abstract

The application relates to the field of electric machines, and discloses a voice coil motor with a magnetic gravity compensation structure, which comprises a mover unit and a stator unit, the stator unit is slidably sleeved on the mover unit, the mover unit comprises a coil assembly, the mover unit comprises a first gravity compensation magnet and a second gravity compensation magnet, the first gravity compensation magnet and the second gravity compensation magnet are located above and below the coil assembly respectively, the stator unit comprises a stator magnet assembly, the stator magnet assembly comprises upper surface magnets and lower surface magnets which are distributed upwards and downwards, the first gravity compensation magnet and the upper surface magnets repel each other, and the second gravity compensation magnet and the lower surface magnets repel each other, so as to constantly compensate the gravity of the mover unit, make the mover unit float, and improve the gravity compensation linearity and rigidity, reduce current consumption and heat generation, avoid precision errors caused by thermal expansion, and have the advantages of simple and compact structure, convenient assembly and low production cost.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a voice coil motor with a magnetic gravity compensation structure. Background Technology

[0002] A voice coil motor is a linear motion actuator that converts electrical energy into mechanical energy. Unlike traditional servo motors that work with ball screws, voice coil motors can directly drive loads. Therefore, voice coil motors offer advantages such as simple structure, maintenance-free operation, high response, and high precision, and are widely used in semiconductor and industrial automation applications.

[0003] When a voice coil motor is used as a vertical motion axis, it requires additional current to overcome the weight of the mover and the load. The required current increases accordingly with heavier loads. According to Joule's law, the heat generated by the motor is proportional to the square of the current, thus generating significant heat and causing the system temperature to rise. Based on the coefficient of thermal expansion of materials, excessively high temperatures can cause significant deformation, thereby reducing the system's accuracy. This is particularly evident in applications requiring extremely high precision, such as lithography machines.

[0004] To address the aforementioned issues, the industry has proposed technical solutions using magnetic gravity compensators to counteract gravity. Existing patents with publication numbers WO2011131462A1, US9172291B2, US6791443B2, CN105281530B, and CN103034065B propose several structures for magnetic gravity compensators. However, these require the use of conical permanent magnets or radially magnetized permanent magnets, resulting in high costs and difficulty in integrating them with voice coil motors. Patent publication number CN212572354U proposes a variable-rigidity magnetic gravity compensator, which requires the insertion of mechanical springs or hinge structures into the original structure to achieve constant gravity compensation. This structure is more complex and has lower reliability; the output force of the springs or hinges varies with deformation, making constant gravity compensation impossible. Summary of the Invention

[0005] To address at least one of the aforementioned problems, the present invention first provides a voice coil motor with a magnetic gravity compensation structure, comprising a moving unit and a stator unit. The stator unit is slidably mounted on the moving unit. The moving unit includes a coil assembly and a first gravity compensation magnet and a second gravity compensation magnet, which are located above and below the coil assembly, respectively. The stator unit includes a stator magnet assembly, which includes an upper surface magnet and a lower surface magnet distributed vertically. The first gravity compensation magnet and the upper surface magnet are mutually exclusive, and the second gravity compensation magnet and the lower surface magnet are mutually exclusive.

[0006] Optionally, the moving unit includes a cylindrical coil frame, the coil frame including a first mounting portion at the upper end and a second mounting portion on the periphery, the first gravity compensation magnet is mounted on the bottom of the first mounting portion, the coil assembly is wound around the second mounting portion, and the second gravity compensation magnet is mounted on the bottom side wall of the second mounting portion.

[0007] Optionally, the stator unit includes an outer yoke, the upper surface magnet and the lower surface magnet are coaxially arranged, the lower surface magnet is mounted on the bottom of the outer yoke, a sliding cavity is formed between the stator magnet assembly and the peripheral wall of the outer yoke, and the second mounting part is slidably connected to the sliding cavity.

[0008] Optionally, both the moving unit and the stator unit are cylindrical, and the moving unit and the stator unit are coaxially arranged. The bottom of the outer yoke is provided with an opening, and an axial cavity is formed between the opening and the stator magnet assembly to facilitate magnetization.

[0009] Optionally, the upper surface magnet and the lower surface magnet are mutually exclusive, and the stator unit further includes a first radial yoke and a second radial yoke, the first radial yoke being installed at the upper end of the upper surface magnet, and the second radial yoke being installed between the upper surface magnet and the lower surface magnet.

[0010] Optionally, the first gravity compensation magnet is located directly above the upper surface magnet.

[0011] Optionally, the N-pole directions of the first gravity compensation magnet and the second gravity compensation magnet are the same, the N-pole directions of the upper surface magnet and the lower surface magnet are opposite, and the N-pole directions of the first gravity compensation magnet, the second gravity compensation magnet, and the lower surface magnet are all the same.

[0012] Optionally, the number of coil assemblies is the same as the number of stator magnet assemblies. Each coil assembly includes a first coil and a second coil distributed vertically. The first gravity compensation magnet is located above the first coil, and the second gravity compensation magnet is located below the second coil.

[0013] Optionally, a first repulsive force in the vertical direction is generated between the upper surface magnet and the first gravity compensation magnet, and a second repulsive force in the vertical direction is generated between the lower surface magnet and the second gravity compensation magnet. Both the first and second repulsive forces are used to compensate for the gravity of the moving subunit, so that the moving subunit is suspended above the stator unit.

[0014] Optionally, the first repulsive force decreases as the distance between the upper surface magnet and the first gravity compensation magnet increases, and the second repulsive force increases as the distance between the lower surface magnet and the second gravity compensation magnet increases. The first repulsive force and the second repulsive force work together to generate a resultant force, which is used to compensate for the gravity of the moving subunit. The resultant force is a constant value or approximately a constant value.

[0015] Compared to existing technologies, the voice coil motor with a magnetic gravity compensation structure in this invention:

[0016] 1. Good stiffness characteristics: Through the repulsive force cooperation between the upper surface magnet and the first gravity compensation magnet, and the repulsive force cooperation between the lower surface magnet and the second gravity compensation magnet, a constant compensation force is provided to compensate for the gravity of the moving unit, so that the moving unit is suspended relative to the stator unit. The gravity compensation linearity is good and the stiffness is large.

[0017] 2. Easy to integrate with voice coil motors: The gravity compensator structure disclosed in this invention can be directly integrated with a cylindrical voice coil motor, saving design space and making the structure more compact.

[0018] 3. Low temperature rise: Since the gravity compensation structure cancels out the gravity, the Ampere force only needs to provide the force required for dynamic adjustment, thus greatly reducing current consumption and heat generation, avoiding accuracy errors caused by thermal expansion, and making it suitable for high-precision applications such as semiconductors.

[0019] 4. Simple manufacturing: The magnetization direction in the technical solution of this invention is axial magnetization, without radial magnetization of the magnetic ring. The structure is simple, easy to assemble, low in production cost, and can be easily integrated with cylindrical voice coil motors.

[0020] 5. Does not include springs or hinges: This avoids the output force of springs or hinges changing with deformation, thus preventing the inability to achieve constant gravity compensation. Attached Figure Description

[0021] Figure 1This is a cross-sectional view of a voice coil motor with a magnetic gravity compensation structure according to an embodiment of the present invention;

[0022] Figure 2 This is a waveform diagram of the first repulsive force according to an embodiment of the present invention;

[0023] Figure 3 This is a second repulsive force waveform diagram according to an embodiment of the present invention;

[0024] Figure 4 This is a waveform diagram of the repulsive force experienced by the entire moving unit in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Moving element; 11. First coil; 12. Second coil; 13. First gravity compensation magnet; 14. Second gravity compensation magnet; 15. Coil frame; 151. First mounting part; 152. Second mounting part; 2. Stator unit; 21. Upper surface magnet; 22. Lower surface magnet; 23. First radial yoke; 24. Second radial yoke; 25. Outer yoke; 251. Sliding cavity; 252. Cavity. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] This invention provides a voice coil motor with a magnetic gravity compensation structure, combined with Figures 1 to 4 As shown, the device includes a moving unit 1 and a stator unit 2. The stator unit 2 is slidably sleeved on the moving unit 1. The moving unit 1 includes a coil assembly and a first gravity compensation magnet 13 and a second gravity compensation magnet 14. The first gravity compensation magnet 13 and the second gravity compensation magnet 14 are located above and below the coil assembly, respectively. The stator unit 2 includes a stator magnet assembly, which includes an upper surface magnet 21 and a lower surface magnet 22 distributed vertically. The first gravity compensation magnet 13 and the upper surface magnet 21 are mutually repulsive, and the second gravity compensation magnet 14 and the lower surface magnet 22 are mutually repulsive.

[0029] like Figure 1 As shown, optionally, the moving unit 1 includes a cylindrical coil frame 15, the coil frame 15 includes a first mounting portion 151 at the upper end and a second mounting portion 152 on the periphery, the first gravity compensation magnet 13 is mounted on the bottom of the first mounting portion 151, the coil assembly is wound around the second mounting portion 152, and the second gravity compensation magnet 14 is mounted on the bottom side wall of the second mounting portion 152.

[0030] Optionally, the stator unit 2 includes an outer yoke 25, the upper surface magnet 21 and the lower surface magnet 22 are coaxially arranged, the lower surface magnet 22 is mounted on the bottom of the outer yoke 25, a sliding cavity 251 is formed between the stator magnet assembly and the peripheral wall of the outer yoke 25, and the second mounting part 152 is slidably connected to the sliding cavity 251.

[0031] Optionally, both the moving unit 1 and the stator unit 2 are cylindrical, and are coaxially arranged. The bottom of the outer yoke 25 has an opening, and an axial cavity 252 is formed between the opening and the stator magnet assembly to facilitate magnetization. In this embodiment, the outer yoke 25 also has magnetic force, which is prior art. For details, please refer to the basic principle of the voice coil motor, which will not be elaborated here.

[0032] Optionally, the upper surface magnet 21 and the lower surface magnet 22 are mutually exclusive. The stator unit 2 further includes a first radial yoke 23 and a second radial yoke 24. The first radial yoke 23 is installed at the upper end of the upper surface magnet 21, and the second radial yoke 24 is installed between the upper surface magnet 21 and the lower surface magnet 22. The first radial yoke 23 and the second radial yoke 24 are used for magnetic conduction and together with the outer yoke 25 and the stator magnet assembly, form a closed magnetic circuit. This is the basic working principle of a voice coil motor, and the principle of generating the magnetic circuit will not be elaborated here. The first radial yoke 23 is bonded to the upper surface magnet 21, and the upper and lower ends of the second radial yoke 24 are respectively bonded to the upper surface yoke and the lower surface yoke.

[0033] The stator magnet assembly may include multiple axially distributed stator magnets. In this embodiment, only two stator magnets are provided, namely the upper surface magnet 21 and the lower surface magnet 22. In other embodiments, three or four magnets may be provided. It is worth noting that two axially adjacent stator magnets are mutually exclusive, for example... Figure 1 The middle part can be represented as arrows pointing in opposite directions.

[0034] Optionally, the N poles of the first gravity compensation magnet 13 and the second gravity compensation magnet 14 are in the same direction, the N poles of the upper surface magnet 21 and the lower surface magnet 22 are in opposite directions, and the N poles of the first gravity compensation magnet 13, the second gravity compensation magnet 14 and the lower surface magnet 22 are all in the same direction.

[0035] Optionally, the number of coil assemblies is the same as the number of stator magnet assemblies. The coil assembly includes a first coil 11 and a second coil 12 distributed vertically. The first gravity compensation magnet 13 is located above the first coil 11, and the second gravity compensation magnet 14 is located below the second coil 12.

[0036] Optionally, the first gravity compensation magnet 13 is located directly above the upper surface magnet 21. Compared to when the first gravity compensation magnet 13 is directly above the first coil 11, when the first gravity compensation magnet 13 is directly above the upper surface magnet 21, the repulsive force generated is greater, and the gravity compensation effect is better.

[0037] Optionally, the first gravity compensation magnet 13, the second gravity compensation magnet 14, the upper surface magnet 21, and the lower surface magnet 22 are all made of magnetic steel.

[0038] Optionally, a first repulsive force in the vertical direction is generated between the upper surface magnet 21 and the first gravity compensation magnet 13, and a second repulsive force in the vertical direction is generated between the lower surface magnet 22 and the second gravity compensation magnet 14. Both the first and second repulsive forces are used to compensate for the gravity of the moving subunit 1, so that the moving subunit 1 is suspended above the stator unit 2.

[0039] like Figure 1 As shown, in this embodiment, Figure 1 The direction indicated by the middle arrow is the N pole, and the direction opposite to the arrow is the S pole. The S poles of the upper surface magnet 21 and the first gravity compensation magnet 13 repel each other, generating a vertical repulsive force that pushes the first gravity compensation magnet 13 upward, counteracting the gravity of the moving subunit 1 and creating a levitation effect. The bottom of the first mounting part 151 has a mounting groove where the first gravity compensation magnet 13 is adhered. The first repulsive force further pushes the first gravity compensation magnet 13 into a tighter connection with the mounting groove, preventing it from falling off.

[0040] The lower surface magnet 22 and the second gravity compensation magnet 14 are opposite each other in the radial direction. Because the relative movement stroke between the moving unit 1 and the stator unit 2 is very short, such as... Figure 2 As shown, in this embodiment, the travel distance is between -3mm and 2.5mm. Therefore, the N pole of the lower surface magnet 22 and the N pole of the second gravity compensation magnet 14 always maintain a mutual repulsion effect, forming a second repulsive force opposite to the direction of gravity. The first and second repulsive forces together compensate for the gravity of the moving subunit 1, so that the moving subunit 1 can be suspended above the stator unit 2.

[0041] like Figure 2 As shown, when the moving subunit 1 moves upward, the first repulsive force between the upper surface magnet 21 and the first gravity compensation magnet 13 gradually decreases as the distance between them increases. The magnitude of the first repulsive force and the moving distance of the moving subunit 1 have a linear or approximately linear relationship.

[0042] like Figure 3As shown, when the moving subunit 1 moves upward, the second repulsive force between the lower surface magnet 22 and the second gravity compensation magnet 14 gradually increases with the increase of the distance between them. The magnitude of the second repulsive force and the moving distance of the moving subunit 1 have a linear or approximately linear relationship.

[0043] like Figure 4 As shown, the first repulsive force and the second repulsive force combine to make the repulsive force on the entire moving subunit 1 into a resultant force. The resultant force is a constant value or approximately a constant value to ensure the stability of gravity compensation.

[0044] The relationship between the first repulsive force and the moving distance of the moving subunit 1 can be expressed as:

[0045] (d is the distance, )

[0046] The relationship between the second repulsive force and the moving distance of the moving subunit 1 can be expressed as:

[0047] (d is the distance, )

[0048] The resultant force of the first and second repulsive forces:

[0049]

[0050] When satisfied hour,

[0051]

[0052] That is, the gravitational compensation force is constant.

[0053] Compared to existing technologies, the voice coil motor with a magnetic gravity compensation structure in this invention:

[0054] Good stiffness characteristics: Through the repulsive force cooperation between the upper surface magnet 21 and the first gravity compensation magnet 13, and the repulsive force cooperation between the lower surface magnet 22 and the second gravity compensation magnet 14, a constant compensation force is provided to compensate for the gravity of the moving unit 1, so that the moving unit 1 is suspended relative to the stator unit 2. The gravity compensation linearity is good and the stiffness is large.

[0055] Easy to integrate with voice coil motors: The gravity compensator structure disclosed in this invention can be directly integrated with a cylindrical voice coil motor, saving design space and making the structure more compact.

[0056] Low temperature rise: Since the gravity compensation structure cancels out the gravity, the Ampere force only needs to provide the force required for dynamic adjustment, thus greatly reducing current consumption and heat generation, avoiding accuracy errors caused by thermal expansion, and making it suitable for high-precision applications such as semiconductors.

[0057] Simple to manufacture: The magnetization direction in the technical solution of this invention is axial magnetization, without radial magnetization of the magnetic ring. The structure is simple, easy to assemble, low in production cost, and can be easily integrated with cylindrical voice coil motors.

[0058] No springs or hinges included: This avoids the output force of springs or hinges from varying with deformation, thus preventing the inability to achieve constant gravity compensation.

[0059] Similarly, the components included in the "components," "mechanisms," and "devices" of this disclosure can also be flexibly combined. They can be modularly produced according to actual needs and assembled as an independent module; or they can be assembled separately to form a module in this device. The division of the above-mentioned components in this disclosure is only one embodiment for ease of reading and is not intended to limit the scope of protection of this disclosure. Any technical solution that includes the above-mentioned components and has the same function should be understood as an equivalent technical solution of this disclosure.

[0060] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0061] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0063] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0064] It should be noted that when a component is referred to as "fixed to," "set on," "fixed to," or "mounted on" another component, it can be directly on the other component or there may be an intervening component. When a component is considered to be "connected to another component," it can be directly connected to the other component or there may be an intervening component. Furthermore, when a component is considered to be "fixedly connected" to another component, the connection can be detachable or non-detachable, such as through socketing, snap-fitting, integral molding, welding, etc., which are achievable in conventional technologies and will not be elaborated upon here.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The above embodiments are merely illustrative of several implementation methods of this disclosure, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of this disclosure, and these modifications and improvements all fall within the protection scope of this disclosure.

Claims

1. A voice coil motor with a magnetic gravity compensation structure, characterized in that, The system includes a moving unit (1) and a stator unit (2). The stator unit (2) is slidably mounted on the moving unit (1). The moving unit (1) includes a coil assembly and a first gravity compensation magnet (13) and a second gravity compensation magnet (14), which are located above and below the coil assembly, respectively. The stator unit (2) includes a stator magnet assembly, which includes an upper surface magnet (21) and a lower surface magnet (22) distributed vertically. The first gravity compensation magnet (13) and the upper surface magnet (21) are... The second gravity compensation magnet (14) and the lower surface magnet (22) are mutually exclusive; the moving unit (1) includes a cylindrical coil frame (15), the coil frame (15) includes a first mounting part (151) at the upper end and a second mounting part (152) on the periphery, the first gravity compensation magnet (13) is mounted on the bottom of the first mounting part (151), the coil assembly is wound on the second mounting part (152), and the second gravity compensation magnet (14) is mounted on the bottom side wall of the second mounting part (152); the first gravity compensation magnet (13) is located directly above the upper surface magnet (21); The N magnetic poles of the first gravity compensation magnet (13) and the second gravity compensation magnet (14) are in the same direction, and the N magnetic poles of the upper surface magnet (21) and the lower surface magnet (22) are in opposite directions. The N magnetic poles of the first gravity compensation magnet (13), the second gravity compensation magnet (14) and the lower surface magnet (22) are all in the same direction. The coil assembly includes a first coil (11) and a second coil (12) distributed vertically.

2. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that, The stator unit (2) includes an outer yoke (25), the upper surface magnet (21) and the lower surface magnet (22) are coaxially arranged, the lower surface magnet (22) is installed on the bottom of the outer yoke (25), a sliding cavity (251) is formed between the stator magnet assembly and the peripheral wall of the outer yoke (25), and the second mounting part (152) is slidably connected to the sliding cavity (251).

3. The voice coil motor with a magnetic gravity compensation structure according to claim 2, characterized in that, Both the moving unit (1) and the stator unit (2) are cylindrical. The moving unit (1) and the stator unit (2) are coaxially arranged. The bottom of the outer yoke (25) is provided with an opening. An axial cavity (252) is formed between the opening and the stator magnet assembly to facilitate magnetization.

4. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that, The upper surface magnet (21) and the lower surface magnet (22) are mutually exclusive. The stator unit (2) further includes a first radial yoke (23) and a second radial yoke (24). The first radial yoke (23) is installed at the upper end of the upper surface magnet (21), and the second radial yoke (24) is installed between the upper surface magnet (21) and the lower surface magnet (22).

5. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that, The number of coil assemblies is the same as the number of stator magnet assemblies. The first gravity compensation magnet (13) is located above the first coil (11), and the second gravity compensation magnet (14) is located below the second coil (12).

6. The voice coil motor with a magnetic gravity compensation structure according to any one of claims 1-5, characterized in that, A first repulsive force is generated in the vertical direction between the upper surface magnet (21) and the first gravity compensation magnet (13), and a second repulsive force is generated in the vertical direction between the lower surface magnet (22) and the second gravity compensation magnet (14). Both the first and second repulsive forces are used to compensate for the gravity of the moving subunit (1), so that the moving subunit (1) is suspended above the stator unit (2).

7. The voice coil motor with a magnetic gravity compensation structure according to claim 6, characterized in that, The first repulsive force decreases as the distance between the upper surface magnet (21) and the first gravity compensation magnet (13) increases, and the second repulsive force increases as the distance between the lower surface magnet (22) and the second gravity compensation magnet (14) increases. The first repulsive force and the second repulsive force work together to generate a resultant force, which is used to compensate for the gravity of the moving subunit. The resultant force is a constant value.

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