CN113292035A - Large-extrusion-film damping torsion type micro-mechanical actuator - Google Patents
Large-extrusion-film damping torsion type micro-mechanical actuator Download PDFInfo
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- CN113292035A CN113292035A CN202110436877.5A CN202110436877A CN113292035A CN 113292035 A CN113292035 A CN 113292035A CN 202110436877 A CN202110436877 A CN 202110436877A CN 113292035 A CN113292035 A CN 113292035A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
- B81B3/0021—Transducers for transforming electrical into mechanical energy or vice versa
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0035—Constitution or structural means for controlling the movement of the flexible or deformable elements
- B81B3/0059—Constitution or structural means for controlling the movement not provided for in groups B81B3/0037 - B81B3/0056
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/03—Microengines and actuators
- B81B2201/038—Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
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Abstract
The invention provides a large-extrusion-film damping torsion type micro-mechanical actuator which comprises a base, an upper polar plate, a lower polar plate and two supporting pieces, wherein the two supporting pieces are distributed on two sides of the upper polar plate along the width direction of the upper polar plate; each supporting sub-part comprises a fixed supporting part and a twisting supporting beam, the fixed supporting part is fixedly connected with the base, one end of the twisting supporting beam is connected with the fixed supporting part, and the other end of the twisting supporting beam is connected with the upper polar plate; the upper polar plate is parallel to the base and can rotate around a torsion axis formed by the two torsion supporting beams; the lower polar plate is fixed on the upper surface of the base and positioned below the upper polar plate, and a gap is formed between the lower polar plate and the upper polar plate; the length-width ratio of the upper polar plate is 4-8. The large-extrusion-film-damping torsional micro mechanical actuator has large extrusion film damping, small transient overshoot and fast convergence during starting, and fast amplitude attenuation during stopping.
Description
Technical Field
The invention belongs to the technical field of micro-electronic machinery, and particularly relates to a large-extrusion-film damping torsion type micro-mechanical actuator.
Background
The twisted active plate is the core of many micromechanical actuators, which are typically fabricated from silicon. Fig. 1 is a schematic diagram of a conventional torsion-type plate micro-actuator. When no input voltage is applied, the movable plate is parallel to the fixed plate, and the gap between the movable plate and the fixed plate is g0. After the input voltage is applied, the movable polar plate generates torsional motion under the action of electrostatic torque, and the maximum stroke of the device is g0. Under the action of input voltage, the devices must have quite large damping to ensure that the transient overshoot is small and the transient overshoot rapidly converges to an equilibrium position.
Electrostatic drive torque and plate spacing g is disclosed in Microsystem design, Kluwer adaptive publications, 20010Is inversely proportional to the square of. In order to be able to generate a large drive torque with a small drive voltage, the movable plate and the fixed plate must be relatively close together. When the movable polar plate moves downwards, the gas in the gap is compressed and extruded out; when the movable polar plate moves upwards, the gas in the gap is expanded, and the gas around the gap is sucked into the gap. This effect creates a pressure differential between the inside and outside of the gap. This pressure difference has a damping effect. This damping effect is squeeze film damping. Squeeze film damping and plate spacing g is disclosed in Compact analytical modules of size film damping with an indexing conditioning using a Green's function alignment Sens Actuators A70: 32-410The third power of (c) is inversely proportional. To increase squeeze film damping, g may be directly decreased0. However, as a micro-actuator, it must have a large stroke, g, for its application value0It cannot be too small. Therefore, in g0It makes sense to increase squeeze film damping without change.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the large-extrusion-film-damping torsional micro-mechanical actuator has large extrusion film damping, small transient overshoot and fast convergence during starting, and fast amplitude attenuation during stopping.
In order to solve the technical problem, an embodiment of the present invention provides a large squeeze film damping torsion type micro mechanical actuator, which includes a base, an upper polar plate, a lower polar plate and two supporting pieces, wherein the two supporting pieces are arranged on two sides of the upper polar plate along a width direction of the upper polar plate; each supporting sub-part comprises a fixed supporting part and a twisting supporting beam, the fixed supporting part is fixedly connected with the base, one end of the twisting supporting beam is connected with the fixed supporting part, and the other end of the twisting supporting beam is connected with the upper polar plate; the upper polar plate is parallel to the base and can rotate around a torsion axis formed by the two torsion supporting beams; the lower polar plate is fixed on the upper surface of the base and positioned below the upper polar plate, and a gap is formed between the lower polar plate and the upper polar plate; the length-width ratio of the upper polar plate is 4-8.
As a further improvement of the embodiment of the invention, the two torsion supporting beams are respectively connected with two ends of one wide side of the upper polar plate; the length-width ratio of the upper polar plate is 4.
As a further improvement of the embodiment of the invention, the two torsion supporting beams are respectively connected with the middle points of the two long sides of the upper polar plate; the length-width ratio of the upper polar plate is 8.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects: according to the large-extrusion-film-damping torsional micro mechanical actuator provided by the embodiment of the invention, the upper polar plate is the movable electrode, the length-width ratio of the upper polar plate is 4-8, and the large-extrusion-film damping is realized under the condition that the gap between the fixed polar plates is kept, so that the actuator is small in transient overshoot and fast in convergence when being started, and is also fast in amplitude attenuation when being stopped, collision can be avoided, and the actuator is kept to have a small size.
Drawings
Fig. 1 is a schematic structural diagram of a conventional symmetrical torsion-type micro actuator, in which fig. 1(a) is a front view of the conventional symmetrical torsion-type micro actuator, and fig. 1(b) is a top view of the conventional symmetrical torsion-type micro actuator;
fig. 2 is a schematic structural diagram of a single-side asymmetric large squeeze film damping torsion type micro-mechanical actuator according to an embodiment of the present invention, where fig. 2(a) is a front view of the single-side asymmetric large squeeze film damping torsion type micro-mechanical actuator, and fig. 2(b) is a top view of the single-side asymmetric large squeeze film damping torsion type micro-mechanical actuator;
fig. 3 is a schematic structural diagram of a symmetric large squeeze film torsional damping micromechanical actuator according to an embodiment of the present invention, where fig. 3(a) is a front view of the symmetric large squeeze film torsional damping micromechanical actuator, and fig. 3(b) is a top view of the symmetric large squeeze film torsional damping micromechanical actuator.
The figure shows that: the device comprises a base 1, an upper polar plate 2, a lower polar plate 3, a fixed supporting part 41 and a torsion supporting beam 42.
Detailed Description
The technical solution in the embodiments of the present invention will be described more clearly and completely with reference to the accompanying drawings in the embodiments of the present invention.
The embodiment of the invention provides a large-extrusion-film damping torsion type micro-mechanical actuator which comprises a base 1, an upper polar plate 2, a lower polar plate 3 and two supporting pieces, wherein the two supporting pieces are arranged on two sides of the upper polar plate 2 along the width direction (the y-axis direction in figures 2 and 3) of the upper polar plate 2. Each supporting component comprises a fixed supporting part 41 and a twisting supporting beam 42, the fixed supporting part 41 is fixedly connected with the base 1, one end of the twisting supporting beam 42 is connected with the fixed supporting part 41, and the other end of the twisting supporting beam 42 is connected with the upper pole plate 2. The upper polar plate 2 is parallel to the base 1, the two torsion supporting beams are positioned on the same straight line, and the upper polar plate 2 can rotate around a torsion axis formed by the two torsion supporting beams. The lower polar plate 3 is fixed on the upper surface of the base 1, the lower polar plate 3 is positioned below the upper polar plate 2, and a gap is formed between the lower polar plate 3 and the upper polar plate 2. The length-width ratio of the upper polar plate 2 is 4-8. Wherein, the upper polar plate 2 is a rigid rectangular flat plate, and the torsional rigidity of the two torsional supporting beams 42 is the same.
In the above-described embodiment of the torsional micromechanical actuator, the upper plate 2 is a movable electrode, the lower plate 3 is a fixed electrode, the driving voltage is applied between the upper plate 2 and the lower plate 3, and the torsional support beam 42 is elastically twisted and deformed under the action of the electrostatic torque to drive the upper plate 2 to generate torsional displacement around the torsional axis (in the z-axis direction in fig. 2 and 3).
The micromechanical actuator is driven by the step input voltage, and the upper polar plate generates torsional deformation. Such deformations include transient deformations and steady-state deformations, wherein transient deformations are not useful. The transient deformation will gradually decrease under the action of the damping force and finally decay to zero. When the step input stops, the upper plate will return to its original position. At this time, the steady-state deformation is zero, but the transient deformation still exists. When the damping of the device is too small, the transient vibration amplitude is large. In order to avoid collision between the upper plate and other parts of the periphery, the gap between the upper plate and the periphery must be large, so that the overall size and mass of the device are large.
In the torsional micro-mechanical actuator of the embodiment, the length-width ratio of the upper polar plate 2 is 4-8, and the damping of the large extrusion film is realized under the condition of keeping the gap between the polar plates, so that when the actuator is started, the transient overshoot is small, the convergence is fast, the amplitude attenuation is fast when the actuator is stopped, the collision can be avoided, and the actuator is kept to have a small size.
Preferably, as shown in fig. 2, two torsion support beams 42 are connected to both ends of one wide side of the upper plate 2, respectively. The upper plate 2 has an aspect ratio of 4.
The micro-mechanical actuator of the present embodiment is a single-side asymmetric twisted micro-mechanical actuator, and the twisted axis is a wide side of the upper plate (y axis in fig. 2).
According to the theory of squeeze film damping, neglecting the gas compression effect, the torsional vibration squeeze film damping coefficient is as follows:
in the formula IxDenotes the length of the upper plate,/yDenotes the width of the upper plate, g0Denotes the plate spacing and μ denotes the gas viscosity coefficient.
The first term of the number of stages in the formula (1) is also absolutely large. Only the first term is taken, i.e., m-n-1. Since the electrostatic driving force, capacitance are also proportional to the plate area, and changing the area also directly affects the magnitude of the driving force and capacitance, discussion of l will be made without changing the rectangular plate areax、lyAnd damping coefficient cdampingThe relationship (2) of (c). Then formula (1) is changed to:
wherein A ═ lxlyThe area of the upper electrode plate is shown,
representing the aspect ratio of the upper plate. Obviously, the aspect ratio of the upper plate
The larger the size of the tube is,
the smaller, cdampingThe larger. When in use
When c is greater thandampingThere is also a maximum value.
However, it is considered that the aspect ratio of the upper plate is too large, which results in the unidirectional device being too large, and a malformed structure. The aspect ratio of the upper plate in the embodiment of the present invention is 4, i.e.
At this time, the process of the present invention,
the extrusion film damping is very close to the maximum value, and the single-side asymmetric large-extrusion-film damping torsional micro-mechanical actuator provided by the embodiment of the invention has large extrusion film damping.
Preferably, as shown in fig. 3, two torsion support beams 42 are connected to the midpoints of the two long sides of the upper plate 2, respectively. The upper plate 2 has an aspect ratio of 8.
The micromechanical actuator of this embodiment is a symmetrical torsion type micromechanical actuator, and the torsion axis is the center line of the upper plate 2 (y axis in fig. 3).
According to the theory of squeeze film damping, the gas compression effect can be ignored, and the damping coefficient of the torsional vibration squeeze film is as follows:
in the formula IxDenotes the length of the upper plate,/yDenotes the width of the upper plate, g0Denotes the plate spacing and μ denotes the gas viscosity coefficient.
The first term of the number of stages in the formula (1) is also absolutely large. Only the first term is taken, i.e., m-2 and n-1. Since the electrostatic driving force, capacitance are also proportional to the plate area, and changing the area also directly affects the magnitude of the driving force and capacitance, discussion of l will be made without changing the rectangular plate areax、lyAnd damping coefficient cdampingThe relationship (2) of (c). Then formula (1) is changed to:
wherein A ═ lxlyThe area of the upper electrode plate is shown,
representing the aspect ratio of the upper plate. Obviously, the aspect ratio of the upper plate
The larger the size of the tube is,
the smaller is cdampingThe larger. When the aspect ratio beta is infinite,
cdampingthere is a maximum value.
However, it is considered that the aspect ratio of the upper plate is too large, which results in the unidirectional device being too large, and a malformed structure. The aspect ratio of the upper plate in the embodiment of the present invention is 8, that is
At this time, the process of the present invention,
the squeeze film damping is very close to the maximum value, and the symmetrical large squeeze film damping torsional micro-mechanical actuator provided by the embodiment of the invention has large squeeze film damping.
Two specific examples are provided below to demonstrate the large squeeze film damping of the micromechanical actuator according to embodiments of the present invention.
Example 1
The torsional micro-mechanical actuator is of a symmetrical structure: area A of the upper plate is 800 μm2Length lx80 μm wide
ly＝10μm。
The obtained membrane damping coefficient of the micro-mechanical actuator is as follows:
comparative example 1
The torsional micro-mechanical actuator is of a symmetrical structure: the length and width of the upper plate are equal, lx＝ly＝28.28μm。
The obtained membrane damping coefficient of the micro-mechanical actuator is as follows:
example 1 the membrane damping coefficient of example 1 is 5 times greater than that of comparative example 1 compared to comparative example 1.
Example 2
The torsion type micro-mechanical actuator is of a unilateral asymmetric structure: area A of the upper plate is 800 μm2Length lx56.56 μm widey＝14.14μm。
The obtained membrane damping coefficient of the micro-mechanical actuator is as follows:
comparative example 2
Torsion type microcomputerThe mechanical actuator is of a symmetrical structure: the length and width of the upper plate are equal, lx＝ly＝28.28μm。
The obtained membrane damping coefficient of the micro-mechanical actuator is as follows:
example 2 compared to comparative example 2, the membrane damping coefficient of example 2 was 2 times that of comparative example 2.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are intended to further illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is also intended to be covered by the appended claims. The scope of the invention is defined by the claims and their equivalents.
Claims (3)
1. The large-extrusion-film damping torsion type micro-mechanical actuator is characterized by comprising a base (1), an upper polar plate (2), a lower polar plate (3) and two supporting pieces, wherein the two supporting pieces are distributed on two sides of the upper polar plate (2) along the width direction of the upper polar plate (2); each supporting sub-component comprises a fixed supporting part (41) and a twisting supporting beam (42), the fixed supporting part (41) is fixedly connected with the base (1), one end of the twisting supporting beam (42) is connected with the fixed supporting part (41), and the other end of the twisting supporting beam (42) is connected with the upper polar plate (2); the upper polar plate (2) is parallel to the base (1), and the upper polar plate (2) can rotate around a torsion axis formed by the two torsion supporting beams; the lower polar plate (3) is fixed on the upper surface of the base (1), the lower polar plate (3) is positioned below the upper polar plate (2), and a gap is formed between the lower polar plate (3) and the upper polar plate (2); the length-width ratio of the upper polar plate (2) is 4-8.
2. The large squeeze film damped torsion type micromechanical actuator according to claim 1, characterized in that the two torsion support beams (42) are connected to both ends of one wide side of the upper plate (2), respectively; the length-width ratio of the upper polar plate (2) is 4.
3. The large squeeze film damped torsion type micromechanical actuator according to claim 1, characterized in that two torsion support beams (42) are connected to the middle points of the two long sides of the upper plate (2), respectively; the length-width ratio of the upper polar plate (2) is 8.
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| CN202110436877.5A CN113292035A (en) | 2021-04-22 | 2021-04-22 | Large-extrusion-film damping torsion type micro-mechanical actuator |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020000364A1 (en) * | 2000-05-24 | 2002-01-03 | Soung-Cheol Hong | Push-pull type micromachined microwave switch |
| CN1844933A (en) * | 2006-05-16 | 2006-10-11 | 北京航空航天大学 | Pendulous silicon MEMS angular acceleration transducer |
| CN103780221A (en) * | 2014-01-02 | 2014-05-07 | 东南大学 | Torsional microcomputer electric resonance device with low thermal elastic damping structure |
| CN109911841A (en) * | 2019-03-19 | 2019-06-21 | 东南大学 | A kind of maximum capacity plate antenna microactrator of squeeze-film damping |
| CN110661505A (en) * | 2019-09-04 | 2020-01-07 | 东南大学 | Low-extrusion-film damping micromechanical resonator with large length-width ratio structure |
-
2021
- 2021-04-22 CN CN202110436877.5A patent/CN113292035A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20020000364A1 (en) * | 2000-05-24 | 2002-01-03 | Soung-Cheol Hong | Push-pull type micromachined microwave switch |
| CN1844933A (en) * | 2006-05-16 | 2006-10-11 | 北京航空航天大学 | Pendulous silicon MEMS angular acceleration transducer |
| CN103780221A (en) * | 2014-01-02 | 2014-05-07 | 东南大学 | Torsional microcomputer electric resonance device with low thermal elastic damping structure |
| CN109911841A (en) * | 2019-03-19 | 2019-06-21 | 东南大学 | A kind of maximum capacity plate antenna microactrator of squeeze-film damping |
| CN110661505A (en) * | 2019-09-04 | 2020-01-07 | 东南大学 | Low-extrusion-film damping micromechanical resonator with large length-width ratio structure |
Non-Patent Citations (1)
| Title |
|---|
| PU LI等: "An Analytical Model for Squeeze-Film Damping of Perforated Torsional Microplates Resonators", SENSORS 2015, vol. 15, no. 4, 25 March 2015 (2015-03-25), pages 7388 - 7411 * |
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