Voice coil motor with magnetic gravity compensation structure

Abstract

The invention relates to the field of motors, and discloses a voice coil motor with a magnetic gravity compensation structure, comprising a rotor unit and a stator unit, the stator unit slidably sleeves the rotor unit, the rotor unit comprises a coil assembly, the rotor 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 an upper surface magnet and a lower surface magnet which are distributed up and down, and the first gravity compensation magnet and the upper surface magnet repel each other. And the second gravity compensation magnet and the lower surface magnet are mutually exclusive to constantly compensate the gravity of the mover unit, so that the mover unit is suspended, the gravity compensation linearity is good, the rigidity is high, the current consumption is reduced, the heating is reduced, the precision error caused by thermal expansion is avoided, the structure is simple and compact, the assembly is convenient, and the production cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a voice coil motor with a magnetic gravity compensation structure. Background Art

[0002] A voice coil motor is a linear motion actuator that converts electrical energy into mechanical energy. Unlike traditional systems that combine a servo motor with a ball screw, a voice coil motor can directly drive the load. As a result, voice coil motors offer advantages such as simple structure, maintenance-free operation, high response, and high precision. They are widely used in applications such as semiconductors and industrial automation.

[0003] When a voice coil motor is used as a vertical motion axis, it requires additional current to overcome the weight of the actuator and load. Heavier loads also require more current. According to Joule's law, the heat generated by the motor is proportional to the square of the current, resulting in significant heat generation and a rise in system temperature. Due to the material's thermal expansion coefficient, excessively high temperatures can cause significant deformation, reducing system accuracy. This is particularly noticeable in applications requiring extremely high precision, such as photolithography equipment.

[0004] To address the above issues, the industry has proposed a technical solution using a magnetic gravity compensator to offset gravity. Existing patents with publication numbers WO2011131462A1, US9172291B2, US6791443B2, CN105281530B, and CN103034065B propose several magnetic gravity compensator structures, but these require the use of conical permanent magnets or radially magnetized permanent magnets, which are costly and difficult to integrate with voice coil motors. Patent publication number CN212572354U proposes a magnetic gravity compensator with variable rigidity. This requires inserting a mechanical spring or hinge structure into the original structure to achieve constant gravity compensation. This structure is more complex and has poor reliability. The output force of the spring or hinge varies with the deformation, making it impossible to achieve constant gravity compensation. Summary of the Invention

[0005] In order to solve at least one aspect of the above problems, the present invention first provides a voice coil motor with a magnetic gravity compensation structure, including a mover unit and a stator unit, the stator unit is slidably mounted on the mover unit, the mover unit includes a coil assembly, the mover unit includes a first gravity compensation magnet and a second gravity compensation magnet, the first gravity compensation magnet and the second gravity compensation magnet are respectively located above and below the coil assembly, the stator unit includes a stator magnet assembly, the stator magnet assembly includes an upper surface magnet and a lower surface magnet distributed up and down, the first gravity compensation magnet and the upper surface magnet repel each other, and the second gravity compensation magnet and the lower surface magnet repel each other.

[0006] Optionally, the mover unit includes a cylindrical coil skeleton, the coil skeleton includes a first mounting portion at the upper end and a second mounting portion on the circumferential side, the first gravity compensation magnet is installed at the bottom of the first mounting portion, the coil assembly is wound on the second mounting portion, and the second gravity compensation magnet is installed on the bottom side wall of the second mounting portion.

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

[0008] Optionally, the mover unit and the stator unit are both cylindrical, and are coaxially arranged. An opening is provided at the bottom of the outer iron yoke, and an axial cavity for facilitating magnetization is formed between the opening and the stator magnet assembly.

[0009] Optionally, the upper surface magnet and the lower surface magnet repel each other, and the stator unit further includes a first radial iron yoke and a second radial iron yoke, the first radial iron yoke being installed at the upper end of the upper surface magnet, and the second radial iron 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 magnetic pole directions of the first gravity compensation magnet and the second gravity compensation magnet are the same, the N magnetic pole directions of the upper surface magnet and the lower surface magnet are opposite, and the N magnetic 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 the coil assemblies is the same as the number of the stator magnet assemblies, and the coil assembly includes a first coil and a second coil distributed up and down, the first gravity compensation magnet is arranged above the first coil, and the second gravity compensation magnet is arranged 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 repulsive force and the second repulsive force are used to compensate for the gravity of the mover unit, so that the mover unit is suspended on 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 cooperate to generate a composite force, which is used to compensate for the gravity of the mover unit. The composite force is a constant value or an approximately constant value.

[0015] Compared with the prior art, the voice coil motor with magnetic gravity compensation structure in the present invention has the following advantages:

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

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

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

[0019] 4. Simple manufacturing: The magnetization direction in the technical solution of the present invention is axial magnetization, and does not contain radial magnetization magnetic rings. It has a simple structure, is easy to assemble, has low production cost, and can be easily integrated with a cylindrical voice coil motor.

[0020] 5. No springs or hinges: Avoid changes in the output force of the springs or hinges due to changes in the deformation, and avoid the inability to achieve constant gravity compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1is 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 is a first repulsive force waveform diagram according to an embodiment of the present invention;

[0023] Figure 3 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 exerted on the entire movable unit according to an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] 1. Mover unit; 11. First coil; 12. Second coil; 13. First gravity-compensating magnet; 14. Second gravity-compensating magnet; 15. Coil skeleton; 151. First mounting portion; 152. Second mounting portion; 2. Stator unit; 21. Upper surface magnet; 22. Lower surface magnet; 23. First radial iron yoke; 24. Second radial iron yoke; 25. Outer iron yoke; 251. Sliding cavity; 252. Cavity. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] The embodiment of the present invention provides a voice coil motor with a magnetic gravity compensation structure, Figures 1 to 4 As shown, it includes a mover unit 1 and a stator unit 2, the stator unit 2 is slidably mounted on the mover unit 1, the mover unit 1 includes a coil assembly, the mover unit 1 includes 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 respectively located above and below the coil assembly, the stator unit 2 includes a stator magnet assembly, the stator magnet assembly includes an upper surface magnet 21 and a lower surface magnet 22 distributed above and below, the first gravity compensation magnet 13 and the upper surface magnet 21 repel each other, and the second gravity compensation magnet 14 and the lower surface magnet 22 repel each other.

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

[0030] Optionally, the stator unit 2 includes an outer iron 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 iron yoke 25, a sliding cavity 251 is formed between the stator magnet assembly and the peripheral wall of the outer iron yoke 25, and the second mounting portion 152 and the sliding cavity 251 are slidably connected.

[0031] Optionally, the mover unit 1 and the stator unit 2 are both cylindrical and coaxially arranged. The outer iron yoke 25 has an opening at its bottom, and an axial cavity 252 is formed between the opening and the stator magnet assembly to facilitate magnetization. In this embodiment, the outer iron yoke 25 also has magnetic force. This is a prior art practice, and reference will be made to the basic principles of voice coil motors for details, which will not be further elaborated here.

[0032] Optionally, the upper surface magnet 21 and the lower surface magnet 22 repel each other, and the stator unit 2 further includes a first radial iron yoke 23 and a second radial iron yoke 24. The first radial iron yoke 23 is mounted on the upper end of the upper surface magnet 21, and the second radial iron yoke 24 is mounted between the upper surface magnet 21 and the lower surface magnet 22. The first radial iron yoke 23 and the second radial iron yoke 24 are used to conduct magnetism and form a closed magnetic circuit together with the outer iron yoke 25 and the stator magnet assembly. This is the basic working principle of the voice coil motor, and the principle of generating the magnetic circuit will not be repeated here. The first radial iron yoke 23 is bonded to the top of the upper surface magnet 21, and the upper and lower ends of the second radial iron yoke 24 are bonded to the upper surface iron yoke and the lower surface iron yoke, respectively.

[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 stator magnets may be provided. It is worth noting that two axially adjacent stator magnets repel each other. Figure 1 It can be represented by arrows pointing in opposite directions.

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

[0035] Optionally, the number of the coil assemblies is the same as the number of the stator magnet assemblies, and the coil assembly includes a first coil 11 and a second coil 12 distributed above and below, the first gravity compensation magnet 13 is arranged above the first coil 11, and the second gravity compensation magnet 14 is arranged 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 located directly above the first coil 11, when the first gravity compensation magnet 13 is located directly above the upper surface magnet 21, a greater repulsive force is generated, and a better gravity compensation effect is achieved.

[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 repulsive force and the second repulsive force are used to compensate for the gravity of the mover unit 1, so that the mover unit 1 is suspended on the stator unit 2.

[0039] like Figure 1 As shown, in this embodiment, Figure 1 The direction indicated by the arrow is the N pole, and the direction opposite to the arrow is the S pole. The S pole of the upper surface magnet 21 and the S pole of the first gravity compensation magnet 13 repel each other with the same poles, generating a first repulsive force in the vertical direction, pushing the first gravity compensation magnet 13 upward to counteract the gravity of the rotor unit 1 and create a levitation effect. A mounting groove is provided at the bottom of the first mounting portion 151, and the first gravity compensation magnet 13 is bonded to the mounting groove. The first repulsive force can also push the first gravity compensation magnet 13 to abut against the mounting groove more tightly to prevent it from falling off.

[0040] The lower surface magnet 22 and the second gravity compensation magnet 14 are opposite to each other in the radial direction. Since the relative movement distance between the mover unit 1 and the stator unit 2 is very short, as shown in FIG. Figure 2 As shown, in this embodiment, the travel range is between -3 mm and 2.5 mm. Therefore, the north pole of the lower surface magnet 22 and the north pole of the second gravity compensation magnet 14 always maintain a mutual repulsion effect, forming a second repulsive force in the opposite direction of gravity. The first and second repulsive forces jointly compensate for the gravity of the mover unit 1, allowing the mover unit 1 to float on the stator unit 2.

[0041] like Figure 2 As shown, when the mover unit 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 the two increases. The magnitude of the first repulsive force and the moving distance of the mover unit 1 are linear or approximately linear.

[0042] like Figure 3As shown, when the mover unit 1 moves upward, the second repulsive force between the lower surface magnet 22 and the second gravity compensation magnet 14 gradually increases as the distance between the two increases. The magnitude of the second repulsive force and the moving distance of the mover unit 1 are linear or approximately linear.

[0043] like Figure 4 As shown, the first repulsive force and the second repulsive force are combined to form a composite force on the entire mover unit 1. The composite force is a constant value or an approximately constant value to ensure the stability of gravity compensation.

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

[0045] (d is the distance, )

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

[0047] (d is the distance, )

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

[0049]

[0050] When satisfied hour,

[0051]

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

[0053] Compared with the prior art, the voice coil motor with magnetic gravity compensation structure in the present invention has the following advantages:

[0054] Good stiffness characteristics: through the repulsive force coordination between the upper surface magnet 21 and the first gravity compensation magnet 13, and the repulsive force coordination 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 mover unit 1, so that the mover unit 1 is suspended relative to the stator unit 2, with good gravity compensation linearity and high stiffness.

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

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

[0057] Simple manufacturing: The magnetization direction in the technical solution of the present invention is axial magnetization, and does not include radial magnetization magnetic rings. It has a simple structure, is easy to assemble, has low production cost, and can be easily integrated with a cylindrical voice coil motor.

[0058] No springs or hinges are included: This prevents the output force of the spring or hinge from changing with the deformation, thus preventing the inability to achieve constant gravity compensation.

[0059] Equivalently, the components included in the "assembly," "mechanism," and "device" of the present disclosure can also be flexibly combined. They can be modularly produced according to actual conditions and assembled as a separate module; or they can be assembled separately to form a module in the present device. The division of the above components in the present disclosure is only one embodiment, for ease of reading, and not to limit the scope of protection of the present disclosure. As long as the above components are included and have the same functions, it should be understood that they are equivalent technical solutions of the present disclosure.

[0060] In the description of the present disclosure, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the present 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 the technical features being referred to. Thus, a feature defined as "first," "second," etc., may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0062] In this disclosure, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components, unless otherwise expressly limited. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on specific circumstances.

[0063] In this disclosure, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0064] It should be noted that when an element is referred to as being “fixed to,” “disposed on,” “fixed on,” or “installed on” another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be “connected to another element,” it may be directly connected to the other element or there may be an intermediate element at the same time. Furthermore, when an element is considered to be “fixedly connected” to another element, the two may be fixed in a detachable connection manner or in a non-detachable connection manner, such as socketing, snap-fitting, integral molding, welding, etc., which can be achieved in traditional technologies and will not be repeated here.

[0065] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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 merely illustrate several implementations of the present disclosure, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the inventive concept of the present disclosure, and all such variations and improvements fall within the scope of protection of the present disclosure.

Claims

1. A voice coil motor with a magnetic gravity compensation structure, characterized in that: The invention comprises a mover unit (1) and a stator unit (2), wherein the stator unit (2) is slidably mounted on the mover unit (1), the mover unit (1) comprises a coil assembly, the mover unit (1) comprises 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) being located above and below the coil assembly, respectively, the stator unit (2) comprises a stator magnet assembly, the stator magnet assembly comprises an upper surface magnet (21) and a lower surface magnet (22) distributed above and below, the first gravity compensation magnet (13) and the upper surface magnet (21) repel each other, and the second gravity compensation magnet (14) and the lower surface magnet (22) repel each other.

2. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that: The mover unit (1) includes a cylindrical coil skeleton (15), the coil skeleton (15) includes a first mounting portion (151) at the upper end and a second mounting portion (152) on the circumferential side, the first gravity compensation magnet (13) is mounted on the bottom of the first mounting portion (151), the coil assembly is wound on 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).

3. The voice coil motor with a magnetic gravity compensation structure according to claim 2, characterized in that: The stator unit (2) includes an outer iron 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 iron yoke (25), a sliding cavity (251) is formed between the stator magnet assembly and the peripheral wall of the outer iron yoke (25), and the second mounting portion (152) and the sliding cavity (251) are slidably connected.

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

5. 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) repel each other, and the stator unit (2) further includes a first radial iron yoke (23) and a second radial iron yoke (24), wherein the first radial iron yoke (23) is mounted on the upper end of the upper surface magnet (21), and the second radial iron yoke (24) is mounted between the upper surface magnet (21) and the lower surface magnet (22).

6. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that: The first gravity compensation magnet (13) is located directly above the upper surface magnet (21).

7. The voice coil motor with a magnetic gravity compensation structure according to claim 1, characterized in that: The N magnetic pole directions of the first gravity compensation magnet (13) and the second gravity compensation magnet (14) are the same, the N magnetic pole directions of the upper surface magnet (21) and the lower surface magnet (22) are opposite, and the N magnetic pole directions of the first gravity compensation magnet (13), the second gravity compensation magnet (14) and the lower surface magnet (22) are all the same.

8. The voice coil motor with a magnetic gravity compensation structure according to claim 1, wherein: The number of the coil assemblies is the same as the number of the stator magnet assemblies. The coil assembly comprises a first coil (11) and a second coil (12) distributed above and below. The first gravity compensation magnet (13) is arranged above the first coil (11), and the second gravity compensation magnet (14) is arranged below the second coil (12).

9. The voice coil motor with a magnetic gravity compensation structure according to any one of claims 1 to 8, characterized in that: 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 repulsive force and the second repulsive force are used to compensate for the gravity of the mover unit (1), so that the mover unit (1) is suspended on the stator unit (2).

10. The voice coil motor with a magnetic gravity compensation structure according to claim 9, 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 cooperate to generate a composite force, and the composite force is used to compensate for the gravity of the mover unit. The composite force is a constant value or an approximately constant value.

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