A near-zero stiffness micro-nano motor

Abstract

The present invention discloses a near-zero stiffness micro-nano motor; the motor includes a stator, a mover, and an Euler buckling beam-leaf spring flexible guide mechanism. The stator is fixed to a base and forms a symmetrical motor body with the mover, with its axis of symmetry perpendicular to a first coordinate axis. The mover includes multiple first iron cores and permanent magnets, and the stator includes multiple second iron cores and coils. The permanent magnets form a bias magnetic circuit between the first and second iron cores and the gaps between them. When the coils are energized, a variable magnetic circuit is formed between the first and second iron cores and the gaps between them. Under the combined action of the bias and variable magnetic circuits, the mover generates motion along the first coordinate axis. The Euler buckling beam-leaf spring flexible guide mechanism consists of multiple Euler buckling beams and multiple leaf springs. The Euler buckling beams are arranged along the first coordinate axis, and the leaf springs along the second coordinate axis. The first and second coordinate axes are perpendicular to each other and symmetrically arranged along the motor's axis of symmetry. The present invention can achieve motor motion guidance while simultaneously compensating for the motor's negative stiffness throughout its entire stroke.

Description

Technical Field

[0001] The present invention relates to the technical field of precision actuators, and in particular to a near-zero stiffness micro-nano motor. Background Art

[0002] Motors (including voice coil motors, reluctance motors, hybrid reluctance motors, etc.) that can achieve nanometer-level scanning and tracking motion accuracy on millimeter-level travel are one of the core components of high-end precision manufacturing and testing equipment (such as lithography machines, micro-nano 3D printing, film thickness detection, etc.). Taking ASML's high-end lithography machines as an example, the positioning accuracy of its motion stage has reached the sub-nanometer level, and the acceleration has reached 120m / s. 2 , approaching its limit. When the overlay accuracy and productivity of the next generation of lithography machines need to be further improved, the micro-motion stage will need to have higher motion accuracy, speed, and acceleration, which will place higher demands on the motion accuracy limit and thrust density limit of the micro-motion stage motor.

[0003] Compared to voice coil motors, hybrid reluctance motors (HRMs) offer higher thrust density and efficiency, further improving motion stage acceleration while maintaining nanometer-level resolution and achieving millimeter-level travel. However, HRMs exhibit dynamic stiffness, which manifests as negative stiffness in the system transfer function and can easily lead to system instability. Compensating for nonlinearities in HRMs is a key challenge in their practical applications.

[0004] In recent years, Euler buckling beams, which exhibit nonlinear stiffness characteristics, have been successfully applied as negative stiffness regulators in quasi-zero-stiffness vibration dampers. When subjected to a pressure greater than a threshold load, an Euler buckling beam buckles and enters a stable equilibrium state. Its shape exhibits a cosine or sine curve, and its stiffness exhibits a nonlinear distribution. Symmetrically distributed Euler buckling exhibits a variation characteristic similar to the nonlinear negative stiffness of a reluctance motor. Therefore, by rationally designing the Euler buckling mechanism and its parameters, a positive stiffness compensation mechanism can be obtained that closely matches the nonlinear negative stiffness distribution of a reluctance motor, achieving near-zero stiffness design across the entire reluctance motor stroke. Summary of the Invention

[0005] To address the shortcomings of the aforementioned prior art, the present invention, based on the principle of parallel cancellation of positive and negative stiffness, proposes a near-zero-stiffness micro-nano motor that uses a nonlinear, positive-stiffness Euler buckled beam for full-stroke negative stiffness compensation and motion guidance. This invention utilizes an Euler buckled beam-leaf spring flexible guidance mechanism to achieve motion guidance and simultaneously compensate for the motor's negative stiffness throughout its entire stroke.

[0006] The technical solution of the present invention is specifically described as follows.

[0007] The present invention provides a near-zero stiffness micro-nano motor, which includes a mover, a stator, an Euler buckled beam-leaf spring flexible guide mechanism and a base;

[0008] The motor is a hybrid reluctance motor. The mover and stator form a motor body. When current is applied, the mover is subjected to a resultant force in the positive / negative direction of the first coordinate axis. The stator is fixed on a base.

[0009] The mover includes a plurality of first iron cores and a plurality of permanent magnets, and the stator includes a plurality of second iron cores and a plurality of coils. The first iron core is T-shaped, with one end face thereof facing the permanent magnet, and the other two end faces are arranged along the first coordinate axis and facing the end face of the second magnetic conductor; the second iron core is C-shaped, with two end faces thereof facing the two end faces of the corresponding first iron core respectively, and the plurality of coils are wound around the first iron core and / or the second iron core;

[0010] The multiple permanent magnets form a closed bias magnetic circuit in the first and second cores and the gaps therebetween. When current is passed through the multiple coils, a closed variable magnetic circuit is formed in the first and second cores and the gaps therebetween. Under the combined action of the bias magnetic circuit and the variable magnetic circuit, the mover is subjected to a resultant force in the positive / negative direction of the first coordinate axis. The magnitude and direction of the force applied to the mover can be controlled by controlling the magnitude and direction of the current passed through the coils.

[0011] The motor body is a symmetrical structure having a first symmetry axis perpendicular to the first coordinate axis;

[0012] The Euler buckling beam and leaf spring structure are arranged on the outside of the hybrid reluctance motor, the Euler buckling beam is arranged along the first coordinate axis, one end is fixed on the stator / base, and the other end is fixed on the mover; the leaf spring structure is arranged along the second coordinate axis, one end is fixed on the stator / base, and the other end is fixed on the mover; the first coordinate axis and the second coordinate axis are perpendicular to each other; the multiple Euler buckling beams and leaf spring structures are symmetrically arranged along the first symmetry axis.

[0013] The original length of the Euler buckled beam is l, and the threshold load is added After that, the length of the Euler buckled beam is shortened by x0, and an initial deflection of a0 is generated, where E is the elastic modulus and I is the moment of inertia. The relationship between the added load F of the Euler buckled beam and the resulting displacement x can be expressed as

[0014]

[0015] Then the stiffness of a single Euler buckled beam is

[0016] The negative stiffness of the motor body can be obtained through finite element analysis;

[0017] The leaf spring structure has a constant positive stiffness k0. By adjusting the parameters E, l, I, and k0, the Euler-buckled beam-leaf spring flexible guide mechanism can generate a positive stiffness that is similar in magnitude to, and opposite in direction to, the negative stiffness of the motor. The parameters of the Euler-buckled beam-leaf spring flexible guide mechanism can be designed using MATLAB software using a trial-and-error method based on the formula. Alternatively, an optimization method can be used to ensure that the stiffness of the Euler-buckled beam-leaf spring flexible guide mechanism matches the stiffness of the motor as closely as possible, thereby determining the corresponding parameters.

[0018] In the present invention, the Euler buckled beam and leaf spring structure together constitute the Euler buckled beam-leaf spring flexible guiding mechanism of the hybrid reluctance motor. This mechanism can not only guide the movement of the hybrid motor rotor in the first coordinate direction, but also compensate for the negative stiffness of the motor, ultimately obtaining the near-zero stiffness micro-nano motor proposed in the present invention.

[0019] In the present invention, the leaf spring structure can be replaced with an air-floating structure, and / or the Euler buckling structure can be arranged between the stator and the mover, which can also achieve negative stiffness compensation and guidance of the hybrid reluctance motor. In this case, the negative stiffness is compensated by the Euler buckling beam alone, and the parameters can also be designed based on the model and with the help of MATLAB, or an optimization method can be adopted. It is worth noting that the negative stiffness compensation of the motor mainly relies on the Euler buckling beam, while the leaf spring structure mainly plays a guiding role, and can be replaced by common guiding mechanisms such as air-floating and magnetic levitation. Moreover, the position of the Euler buckling structure can be adjusted accordingly according to the working conditions.

[0020] Compared with the existing solutions, the present invention has the following beneficial effects:

[0021] The present invention can not only realize the full-stroke negative stiffness compensation of the hybrid reluctance motor, reduce the control difficulty of the motor while utilizing the high thrust efficiency and high thrust density of the hybrid reluctance motor, but also solve the high vibration transmission rate and energy loss problems caused by the high-rigidity flexible guide of the existing reluctance motor, thereby improving the scanning motion accuracy limit and acceleration limit of the hybrid reluctance motor over a millimeter stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural diagram of a specific embodiment 1 provided by the present invention.

[0023] Figure 2 It is a schematic diagram of the Euler buckled beam structure of a specific embodiment 1 provided by the present invention.

[0024] Figure 3 This is the motor stiffness compensation result of a specific embodiment 1 provided by the present invention.

[0025] Figure 4 It is a structural diagram of a specific embodiment 2 provided by the present invention.

[0026] Numbers in the figure: 11 and 13 constitute the stator, 111, 131 - the second iron core, 112, 113, 132, 133 - coils, 12 - mover, 121, 123 - the first iron core, 122 - permanent magnet, 141 - bias magnetic field, 142 - changing magnetic field, 21 and 22 constitute the Euler buckled beam-leaf spring flexible guide mechanism, 211, 222 - leaf spring structure, 212, 221 - symmetric Euler buckled beam structure, 3 - symmetry axis, 231, 234 - air floating module, 232, 233 - the Euler buckled beam placed in the middle. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0028] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," 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 may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0029] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] In the description of the embodiments of the present invention, terms such as "upper," "lower," "right," "inner," and "outer" are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0031] A specific embodiment 1 proposed by the present invention is as follows Figure 1 As shown, the proposed near-zero stiffness hybrid reluctance motor includes stators 11 and 13, a mover 12, an Euler buckled beam-leaf spring flexible guide mechanism 21 and 22, and a base.

[0032] The stators 11, 13, and the mover 12 form a hybrid reluctance motor. The stator comprises an iron core 111, 131 and coils 112, 113, 132, and 133, while the mover comprises an iron core 121, 123 and a permanent magnet 122. The permanent magnet 122 forms a bias magnetic circuit 141 within the iron cores 111, 131, 121, and 123 and the gaps therebetween. When current is applied to the coils 112, 113, 132, and 133, a variable magnetic circuit 142 is formed within the iron cores 111, 131, 121, and 123 and the gaps therebetween. Under the combined action of the bias magnetic circuit 141 and the variable magnetic circuit 142, the mover experiences a resultant force along the positive and negative x-axis, generating corresponding motion. The magnitude and direction of the resultant force can be controlled by varying the magnitude and direction of the current flowing through the coils.

[0033] The Euler buckled beam-leaf spring flexible guide mechanisms 21 and 22 are composed of leaf spring structures 211 and 222 and symmetrical Euler buckled beam structures 212 and 221, which are symmetrically arranged along the symmetry axis 3. The leaf spring structures 211 and 222 are arranged along the y-axis, and the Euler buckled beam structures 212 and 221 are arranged along the x-axis.

[0034] The structure of the Euler buckled beam is as follows Figure 2 Without adding any load, the Euler buckled beam has the following Figure 2 The structure shown in (a) has an initial length of l; when the threshold load is added Afterwards, its length is shortened by x0, and an initial deflection of a0 is generated, as shown in Figure 2 As shown in (b), where E is the elastic modulus and I is the moment of inertia; then, the relationship between the added load F and the resulting displacement x of the Euler buckled beam can be expressed as

[0035]

[0036] Then the stiffness of a single Euler buckled beam is

[0037] The negative stiffness of the motor can be obtained through finite element analysis, such as Figure 3As shown by the corresponding curve in . The leaf spring structure has a constant positive stiffness k0. By adjusting the parameters E, l, I and k0, the Euler buckling beam-leaf spring flexible guide mechanism proposed in this patent can produce a positive stiffness that is similar in magnitude and opposite in direction to the negative stiffness of the motor. The parameters can be adjusted using the trial and error method with the help of matlab software. First, adjust E, l and I so that the stiffness slope of the Euler beam is close to the slope of the motor stiffness, and then adjust k0 so that the distribution of the Euler buckling beam-leaf spring flexible guide mechanism and the motor stiffness are as consistent as possible. An optimization method can also be used to make the stiffness of the Euler buckling beam-leaf spring flexible guide mechanism as close as possible to the motor stiffness, thereby determining the corresponding parameters. A set of results obtained by the present invention is shown as follows Figure 3 As shown, it can be seen that after compensation, the stiffness of the motor is close to 0.

[0038] Furthermore, the Euler buckled beam-leaf spring flexible guide mechanism also enables the hybrid reluctance motor to be guided along the positive and negative x-axis, avoiding the friction issues associated with traditional mechanical guide rails. This ultimately results in the near-zero stiffness motor proposed in this invention.

[0039] A specific embodiment 2 provided by the present invention is as follows Figure 4 As shown, replacing the leaf spring structure with air-floating modules 231 and 234 and placing symmetrical Euler buckling structures 232 and 233 in between can also achieve motion guidance and negative stiffness compensation for the hybrid reluctance motor. In this embodiment, negative stiffness is compensated by an Euler buckling beam. The motor's stiffness distribution is approximated by adjusting the parameters E, l, and I. This can also be adjusted based on the model and with the aid of MATLAB. This embodiment demonstrates that the motor's negative stiffness compensation primarily relies on the Euler buckling beam, while the leaf spring structure primarily serves a guiding role. Common guiding mechanisms such as air-floating or magnetic levitation can be used instead. Furthermore, the position of the symmetrical Euler buckling structure can be adjusted according to actual operating conditions.

[0040] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A near-zero stiffness micro-nano motor, characterized in that: It includes a stator, a mover, an Euler buckled beam-leaf spring flexible guide mechanism and a base; wherein: The motor is a hybrid reluctance motor, wherein the mover and the stator form a motor body having a symmetrical structure; the mover comprises a plurality of first iron cores and permanent magnets, and the stator is fixed on a base and comprises a plurality of second iron cores and a plurality of coils, wherein the coils are wound on the first iron cores and / or the second iron cores; The first iron core is T-shaped, with one end face facing the permanent magnet, and the other two end faces arranged along the first coordinate axis and facing the end face of the second magnetic conductor; The second core is C-shaped, and its two end faces are opposite to the end faces of the two first cores respectively; The permanent magnet generates a closed bias magnetic circuit in the plurality of first iron cores, the second iron cores, and the gaps therebetween. When the coil is energized, a closed variable magnetic circuit is generated in the first iron cores, the second iron cores, and the gaps therebetween. As a result, under the combined action of the bias magnetic circuit and the variable magnetic circuit, the mover is subjected to a resultant force in the positive / negative direction of the first coordinate axis, thereby generating corresponding movement. The motor body has a first symmetry axis perpendicular to the first coordinate axis; The Euler buckled beam-leaf spring flexible guide mechanism comprises a plurality of Euler buckled beams and a plurality of leaf springs; one end of the Euler buckled beams and the leaf springs are fixed to a base or a stator, and the other end is fixed to a mover; the Euler buckled beams are distributed along a first coordinate axis, and the leaf springs are distributed along a second coordinate axis, and the first coordinate axis and the second coordinate axis are perpendicular to each other; the plurality of Euler buckled beams and leaf spring structures are symmetrically arranged along a first symmetry axis; The Euler buckled beam-leaf spring flexible guide mechanism has a positive stiffness that is similar to the negative stiffness distribution of the motor body.

2. The near-zero stiffness micro-nano motor according to claim 1, characterized in that: The leaf spring is placed on the outside of the motor body.

3. The near-zero stiffness micro-nano motor according to claim 1, characterized in that: The Euler buckling beam is placed outside the motor body, or arranged between the mover and the stator, to achieve negative stiffness compensation and guidance of the motor.

4. The near-zero stiffness micro-nano motor according to claim 1, wherein: The design method of the Euler buckled beam-leaf spring flexible guide mechanism is as follows: Assuming the original length of the Euler buckled beam is l, after adding the threshold load After that, the length of the Euler buckled beam is shortened by x0, and an initial deflection of a0 is generated, where E is the elastic modulus and I is the moment of inertia. The relationship between the added load F and the resulting displacement x of the Euler buckled beam is expressed as Then the stiffness of a single Euler buckled beam is The negative stiffness of the motor body is obtained through finite element analysis; The leaf spring structure has a constant positive stiffness k0; Therefore, by adjusting the parameters E, l, I and k0, the Euler buckled beam-leaf spring flexible guide mechanism can generate a positive stiffness that is similar in magnitude and opposite in direction to the negative stiffness of the motor body, thereby obtaining a near-zero stiffness micro-nano motor.

5. The near-zero stiffness micro-nano motor according to claim 1, wherein: The leaf spring in the Euler buckled beam-leaf spring flexible guide mechanism is replaced by an air floating module or a magnetic floating module.

6. The near-zero stiffness micro-nano motor according to claim 5, characterized in that: In the Euler buckled beam-leaf spring flexible guide mechanism, the air floating module or the magnetic floating module is used for guidance. The design method of the Euler buckled beam-leaf spring flexible guide mechanism is as follows: the negative stiffness of the motor body is compensated by the Euler buckled beam, and the threshold load is added by adjusting the original length to l. The elastic modulus E, original length l, and moment of inertia I in the Euler buckled beam are used to approximate the stiffness distribution of the motor, so that the Euler buckled beam-leaf spring flexible guide mechanism generates a positive stiffness that is similar in magnitude and opposite in direction to the negative stiffness of the motor body, thereby obtaining a near-zero stiffness micro-nano motor.

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