An ultrasonic micromotor module with improved driving capacity

Abstract

This invention belongs to the field of micro motor technology, and specifically relates to an ultrasonic micro motor module that can improve driving capability. The technical solution is as follows: an ultrasonic micro motor module with improved driving capability includes a housing, an ultrasonic micro motor stator structure installed inside the housing, a rotor structure sleeved within the ultrasonic micro motor stator structure, and several protrusions provided on the upper and lower surfaces of the ultrasonic micro motor stator structure, the protrusions being pressed tightly against the rotor structure. This invention provides an ultrasonic micro motor module with improved driving capability.

Description

Technical Field

[0001] This invention belongs to the field of micro motor technology, and specifically relates to an ultrasonic micro motor module that can improve driving capability. Background Technology

[0002] Micromotors, also known as miniature motors or micro motors, are small in size and capacity. They are commonly used in control systems to detect, process, amplify, execute, or convert electromechanical signals or energy, or to drive mechanical loads. They can also serve as AC or DC power supplies for equipment. Micromotors integrate high-tech industries from multiple disciplines, including electrical engineering, microelectronics, power electronics, computers, automatic control, precision machinery, and new materials. In particular, the application of electronic and new materials technologies has promoted the advancement of micromotor technology. There are numerous types of micromotors (over 5,000 varieties), diverse specifications, and a wide range of market applications, covering all aspects of the national economy, defense equipment, and human life. Micromotors can be found wherever electric drive is required.

[0003] Currently, micromotors are mainly used in the following areas: microrobots, micro low-power actuators, and micro medical detection devices. Microrobots utilize the small size, low operating voltage, and high control precision of micromotors, making them suitable for mobile platforms, micromechanical assembly, maintenance, and nano-positioning. Micro low-power actuators are primarily used to drive rotatable platforms for multifunctional applications such as optical information sensing. Research and fabrication of miniaturized motors using MEMS technology to achieve these applications is currently a key focus of international research in this field. Furthermore, low-power actuation is a major characteristic of these devices, enabling the integration of microsystem control with integrated circuits. Another application is in micro medical detection devices, which also utilize rotatable platforms for applications such as micro-tool manipulation and venous ultrasound imaging.

[0004] MEMS piezoelectric actuators have attracted widespread attention due to their advantages such as small size, light weight, easy integration with substrate structures, high displacement resolution, large output force, large load capacity, fast response speed, and large instantaneous acceleration generated by the solid-state crystallization effect of materials. They are a suitable MEMS actuator technology for providing high-resolution positioning and high dynamic motion characteristics for micromotors.

[0005] However, due to the limited thickness and small size of the drive structure layer of conventionally designed piezoelectric thin film traveling wave micromotors (less than 1 mm thick and several millimeters in diameter), the output torque of the micromotors is limited to a certain extent. Therefore, this patent proposes a solution that maintains the advantages of low-voltage drive and low power consumption of micromotors while ensuring low-cost mass production and achieving a larger torque output, thus solving the problem of insufficient drive torque of micromotors. Summary of the Invention

[0006] In order to solve the above-mentioned problems in the prior art, the purpose of this invention is to provide an ultrasonic micromotor module that can improve driving capability.

[0007] The technical solution adopted in this invention is as follows: An ultrasonic micromotor module with improved driving capability includes a housing, an ultrasonic micromotor stator structure installed inside the housing, a rotor structure sleeved in the ultrasonic micromotor stator structure, and several protrusions on the upper and lower surfaces of the ultrasonic micromotor stator structure, which are pressed against the rotor structure.

[0008] The stator structure of the ultrasonic micromotor of this invention has several protrusions on both its upper and lower surfaces. The upper and lower parts of the rotor structure are respectively pressed against these protrusions on the upper and lower surfaces of the stator structure. When the inverse piezoelectric effect of the piezoelectric film excites the elastic body to generate two orthogonal standing waves that combine to form a traveling wave, both sides of the stator structure drive the rotor structure to rotate via the protrusions. The stator structure of this ultrasonic micromotor employs a double-protrusion design on both sides. The protrusions amplify displacement and tangential motion, and the simultaneous rotation of the rotor shaft on both sides completes the torque output, significantly improving the driving capability.

[0009] In a preferred embodiment of the present invention, the rotor structure includes a lower rotor with a rotating shaft fixed on it. The rotating shaft passes through the stator structure of the ultrasonic micromotor, and the other end of the rotating shaft is connected to an upper rotor. The upper and lower rotors are respectively located on both sides of the ultrasonic micromotor stator structure. The upper rotor engages with the protrusions on the upper surface of the ultrasonic micromotor stator structure, and the lower rotor engages with the protrusions on the lower surface of the ultrasonic micromotor stator structure, thereby enabling the rotor structure to rotate simultaneously from both sides.

[0010] In a preferred embodiment of the present invention, a magnet for attracting the upper rotor is attached to the lower surface of the lower rotor. With the magnet attached to the lower surface, the upper and lower rotors are firmly attracted together by the magnetic force, providing the necessary preload for driving and ensuring that the protrusions on the upper surface and the lower surface are reliably pressed together.

[0011] In a preferred embodiment of the present invention, the rotating shaft has a straight cut on its side, and the upper rotor has a through hole with a straight flange on its side. The rotating shaft and the upper rotor are fitted with a clearance fit, and the straight cut of the rotating shaft and the straight flange of the upper rotor are fitted together. Because of the fit between the straight cut of the rotating shaft and the straight flange of the upper rotor, the upper rotor and the rotating shaft will not rotate relative to each other, and the entire assembly of the upper rotor, lower rotor, and rotating shaft rotates synchronously. The clearance fit between the rotating shaft and the upper rotor ensures that the upper rotor has a small clearance for movement. The upper and lower rotors together drive the rotating shaft to provide torque output outward.

[0012] In a preferred embodiment of the present invention, a plurality of protrusions on the upper surface and a plurality of protrusions on the lower surface of the ultrasonic micromotor stator structure are arranged facing each other. In this case, the protrusions of all the peaks on the upper surface of the ultrasonic micromotor stator structure contact the upper rotor, and the protrusions of all the peaks on the lower surface of the ultrasonic micromotor stator structure contact the lower rotor, thereby ensuring that each peak on both sides contacts the rotor structure through the protrusions, improving the driving effect. The protrusions are fixed to the ultrasonic micromotor stator structure by means of bonding or welding.

[0013] As a preferred embodiment of the present invention, the ultrasonic micromotor stator structure includes an annular elastic substrate, and a plurality of piezoelectric thin film components are arranged along the circumferential direction on both the upper and lower sides of the elastic substrate. The plurality of piezoelectric thin film components on the upper side and the plurality of piezoelectric thin film components on the lower side are offset by half an angle from a single piezoelectric thin film component on the circumference. The driving signal loaded on the plurality of piezoelectric thin film components on the same side changes with equal phase along the circumferential direction.

[0014] In this invention, several piezoelectric thin film components on the upper side and several piezoelectric thin film components on the lower side are offset by half an angle from each individual piezoelectric thin film component on the circumference, causing the peaks and troughs of the standing waves on the upper and lower surfaces to overlap. The advantage of this electrode design is that it reduces the number of electrode leads, thereby reducing packaging complexity. The enhanced cooperation between the front and back sides enables the excitation of traveling waves. Compared with traditional designs, the number of electrodes is reduced by half, which can reduce packaging difficulty.

[0015] The two sides work together to generate traveling waves. The front side of the ultrasonic micromotor stator structure requires two signals to generate standing waves, and the back side of the ultrasonic micromotor stator structure requires two signals to generate standing waves. The front and back electrodes are spatially offset by 1 / 4 wavelength to achieve the superposition of the wave peaks and troughs on the front and back sides.

[0016] As a preferred embodiment of the present invention, the piezoelectric thin film assembly includes a lower electrode, a piezoelectric thin film and an upper electrode arranged in sequence. The lower electrode is grown on the surface of an elastic substrate, a driving signal is applied to the upper electrode, and the lower electrode is grounded.

[0017] As a preferred embodiment of the present invention, a plurality of upper electrodes on the same side of the elastic substrate are sequentially and cyclically loaded with driving signals of phases sin, cos, -sin, and -cos along the circumferential direction.

[0018] Electrode design scheme 1: All upper electrodes are connected to +, and all lower electrodes are connected to GND for polarization. The front upper electrodes are connected in the order of sin, -sin, sin, -sin, and this order is repeated. The reverse upper electrodes are connected in the order of -cos, cos, -cos, cos, and this order is repeated.

[0019] Electrode design scheme two: The upper electrode on the upper surface is connected to +, the upper electrode on the lower surface is connected to -, and all lower electrodes are connected to GND for polarization. The upper electrodes on the front side are connected in the order of sin, -sin, sin, -sin, and this order is repeated. The upper electrodes on the back side are connected in the order of cos, -cos, cos, -cos, and this order is repeated.

[0020] As a preferred embodiment of the present invention, a central hole is provided in the middle of the elastic base, the rotating shaft passes through the central hole, and arc-shaped teeth are evenly arranged on the edge of the elastic base.

[0021] As a preferred embodiment of the present invention, the material of the elastic substrate is one of monocrystalline silicon, ceramic, polyimide, PDMS, stainless steel, copper alloy, and iron-nickel alloy.

[0022] As a preferred embodiment of the present invention, the piezoelectric thin film material is one of PZT, KNN, lead magnesium niobate-lead titanate (PMN-PT), etc.

[0023] The beneficial effects of this invention are as follows: 1. The upper and lower surfaces of the ultrasonic micromotor stator structure of the present invention are provided with a plurality of protrusions, and the upper and lower parts of the rotor structure are respectively pressed against the protrusions on the upper and lower surfaces of the ultrasonic micromotor stator structure. When the inverse piezoelectric effect of the piezoelectric film is used to excite the elastic body to generate two orthogonal standing waves and synthesize a traveling wave, both sides of the ultrasonic micromotor stator structure drive the rotor structure to rotate through the protrusions. The ultrasonic micromotor stator structure of the present invention adopts a double protrusion design on both sides, and the protrusions amplify the displacement and tangential motion. The front and back sides simultaneously drive the rotor shaft to rotate to complete the torque output, which can significantly improve the driving capability.

[0024] 2. In this invention, the upper and lower piezoelectric thin film components are offset by half an angle from each individual piezoelectric thin film component on the circumference, causing the peaks and troughs of the standing waves on the upper and lower surfaces to overlap. The advantage of this electrode design is that it reduces the number of electrodes, lowers packaging complexity, and the enhanced cooperation between the front and back sides enables the excitation of traveling waves. Compared to traditional designs, the number of electrodes is reduced by half, thus reducing packaging difficulty. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is an exploded view of the present invention; Figure 3 This is a schematic diagram illustrating the working principle of the present invention; Figure 4 This is a schematic diagram of the stator structure of an ultrasonic micromotor; Figure 5 This is a schematic diagram of the convex point structure; Figure 6This is a schematic diagram of the working modes of the ultrasonic micromotor stator structure; Figure 7 This is a schematic diagram of the polarization electric field direction for the first polarization scheme; Figure 8 This is a schematic diagram of the polarization electric field for the first polarization scheme; Figure 9 This is a schematic diagram of the electrode connection for the first polarization scheme; Figure 10 This is a schematic diagram of the polarization electric field direction for the second polarization scheme; Figure 11 This is a schematic diagram of the polarization electric field for the second polarization scheme; Figure 12 This is a schematic diagram of the electrode connection for the second polarization scheme.

[0026] In the figure: 1-Housing; 2-Ultrasonic micromotor stator structure; 3-Rotor structure; 21-Protrusion; 22-Elastic substrate; 23-Piezoelectric thin film assembly; 31-Lower rotor; 32-Shaft; 33-Upper rotor; 34-Magnet; 221-Center hole; 222-Arc tooth; 231-Lower electrode; 232-Piezoelectric thin film; 233-Upper electrode; 321-Straight cut; 331-Through hole; 332-Straight flange. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0029] like Figures 1-3 As shown, the ultrasonic micro motor module with improved driving capability in this embodiment includes a housing 1, an ultrasonic micro motor stator structure 2 installed inside the housing 1, a rotor structure 3 sleeved in the ultrasonic micro motor stator structure 2, and several protrusions 21 provided on the upper and lower surfaces of the ultrasonic micro motor stator structure 2, the protrusions 21 being pressed against the rotor structure 3.

[0030] The ultrasonic micromotor stator structure 2 of the present invention has several protrusions 21 on its upper and lower surfaces. The upper and lower parts of the rotor structure 3 are respectively pressed against the protrusions 21 on the upper and lower surfaces of the ultrasonic micromotor stator structure 2. When the elastic body is excited by the inverse piezoelectric effect of the piezoelectric film 232 to generate two orthogonal standing waves and synthesize a traveling wave, the rotor structure 3 is driven to rotate on both sides of the ultrasonic micromotor stator structure 2 through the protrusions 21. The ultrasonic micromotor stator structure 2 of the present invention adopts a double protrusion design on both sides. The protrusions 21 have the effect of amplifying displacement and tangential motion. The two sides simultaneously drive the rotating shaft 32 of the rotor structure 3 to rotate to complete the torque output, which can greatly improve the driving capability.

[0031] Specifically, the rotor structure 3 includes a lower rotor 31, on which a rotating shaft 32 is fixed. The rotating shaft 32 passes through the ultrasonic micromotor stator structure 2, and the other end of the rotating shaft 32 is connected to an upper rotor 33. The upper rotor 33 and the lower rotor 31 are respectively located on both sides of the ultrasonic micromotor stator structure 2. The upper rotor 33 engages with the protrusion 21 on the upper surface of the ultrasonic micromotor stator structure 2, and the lower rotor 31 engages with the protrusion 21 on the lower surface of the ultrasonic micromotor stator structure 2, thereby enabling the rotor structure 3 to rotate simultaneously from both sides.

[0032] The lower rotor 31 has a magnet 34 attached to its lower surface for attracting the upper rotor 33. With the magnet 34 attached to its lower surface, the upper rotor 33 and the lower rotor 31 are firmly attracted together by the magnetic force, providing the necessary preload for driving and ensuring that the protrusion 21 on the upper surface is reliably pressed against the upper rotor 33 and the protrusion 21 on the lower surface is reliably pressed against the lower rotor 31.

[0033] The rotating shaft 32 has a straight cutout 321 on its side, and the upper rotor 33 has a through hole 331. A straight flange 332 is provided on the side of the through hole 331. The rotating shaft 32 and the upper rotor 33 are fitted with a clearance fit, and the straight cutout 321 of the rotating shaft 32 and the straight flange 332 of the upper rotor 33 engage. Because of the engagement between the straight cutout 321 of the rotating shaft 32 and the straight flange 332 of the upper rotor 33, the upper rotor 33 and the rotating shaft 32 will not rotate relative to each other. The upper rotor 33, the lower rotor 31, and the rotating shaft 32 form a synchronous rotating assembly. The clearance fit between the rotating shaft 32 and the upper rotor 33 ensures that the upper rotor 33 has a small clearance for movement. The upper rotor 33 and the lower rotor 31 together drive the rotating shaft 32 to provide outward torque output.

[0034] The protrusions 21 on the upper surface and the lower surface of the ultrasonic micromotor stator structure 2 are arranged facing each other. At this time, the protrusions 21 on all the peaks of the upper surface of the ultrasonic micromotor stator structure 2 are in contact with the upper rotor 33, and the protrusions 21 on all the peaks of the lower surface of the ultrasonic micromotor stator structure 2 are in contact with the lower rotor 31, thus ensuring that each peak on both sides contacts the rotor structure 3 through the protrusions 21, improving the driving effect. The protrusions 21 are fixed to the ultrasonic micromotor stator structure 2 by means of bonding or welding.

[0035] Specifically, such as Figures 4-6 As shown, the ultrasonic micromotor stator structure 2 includes an annular elastic base 22. Several piezoelectric thin film components 23 are arranged along the circumferential direction on both the upper and lower sides of the elastic base 22. The piezoelectric thin film components 23 on the upper side and the piezoelectric thin film components 23 on the lower side are offset by half an angle from each individual piezoelectric thin film component 23 on the circumference. The driving signal loaded on the piezoelectric thin film components 23 on the same side changes phase evenly along the circumferential direction. A central hole 221 is provided in the middle of the elastic base 22, through which the rotating shaft 32 passes. Arc-shaped teeth 222 are evenly arranged along the edge of the elastic base 22.

[0036] In this invention, the upper and lower piezoelectric thin film components 23 are offset by half an angle from each individual piezoelectric thin film component 23 on the circumference, causing the peaks and troughs of the standing waves on the upper and lower surfaces to overlap. The advantage of this electrode design is that it reduces the number of electrodes, lowering the packaging complexity. The enhanced cooperation between the front and back sides enables the excitation of traveling waves. Compared to traditional designs, the number of electrodes is reduced by half, thus reducing packaging difficulty.

[0037] The two sides work together to generate traveling waves. The front side of the ultrasonic micromotor stator structure 2 requires two signals to generate standing waves, and the back side of the ultrasonic micromotor stator structure 2 requires two signals to generate standing waves. The front and back electrodes are spatially offset by 1 / 4 wavelength to achieve the superposition of the wave peaks and troughs on the front and back sides.

[0038] The elastic substrate 22 can be made of monocrystalline silicon, ceramics, flexible materials (including but not limited to polyimide, PDMS, etc.), stainless steel, copper alloy, iron-nickel alloy, etc., with a driving frequency greater than 20KHz to achieve ultrasonic silent driving.

[0039] The piezoelectric thin film assembly 23 includes a lower electrode 231, a piezoelectric thin film 232 and an upper electrode 233 arranged in sequence. The lower electrode 231 is grown on the surface of the elastic substrate 22, the driving signal is applied to the upper electrode 233, and the lower electrode 231 is grounded.

[0040] In this embodiment, taking the B13 mode as the working mode as an example, there are 6 piezoelectric thin film components 23 on both the upper and lower sides of the elastic substrate 22. The upper electrode 233 on the upper surface and the upper electrode 233 on the lower surface are offset by 30° in the circumferential direction, so that the peaks and troughs of the standing waves on the upper and lower surfaces are superimposed.

[0041] On the elastic substrate 22, several upper electrodes 233 on the same side are sequentially and cyclically loaded with driving signals of phases sin, cos, -sin, and -cos along the circumferential direction.

[0042] Different electrode configurations are used depending on the polarization method, as detailed below: like Figures 7-9 As shown, electrode design scheme one: all upper electrodes 233 are connected to +, and all lower electrodes 231 are connected to GND polarization. The front upper electrodes 233 are connected in the order of sin, -sin, sin, -sin, and this order is repeated. The reverse upper electrodes 233 are connected in the order of -cos, cos, -cos, cos, and this order is repeated.

[0043] like Figures 10-12 As shown, electrode design scheme two: the upper electrode 233 on the upper surface is connected to +, the upper electrode 233 on the lower surface is connected to -, and all lower electrodes 231 are connected to GND for polarization. The upper electrode 233 on the front side is connected to sin, -sin, sin, -sin in sequence, and this sequence is repeated. The upper electrode 233 on the back side is connected to cos, -cos, cos, -cos in sequence, and this sequence is repeated.

[0044] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. An ultrasonic micromotor module with improved driving capability, characterized in that: Includes a housing (1), an ultrasonic micro motor stator structure (2) is installed inside the housing (1), a rotor structure (3) is sleeved in the ultrasonic micro motor stator structure (2), and several protrusions (21) are provided on the upper and lower surfaces of the ultrasonic micro motor stator structure (2), and the protrusions (21) are pressed against the rotor structure (3).

2. The ultrasonic micromotor module with improved driving capability according to claim 1, characterized in that: The rotor structure (3) includes a lower rotor (31), a rotating shaft (32) is fixed on the lower rotor (31), the rotating shaft (32) passes through the ultrasonic micro motor stator structure (2), and the other end of the rotating shaft (32) is connected to an upper rotor (33). The upper rotor (33) and the lower rotor (31) are respectively located on both sides of the ultrasonic micro motor stator structure (2).

3. The ultrasonic micromotor module with improved driving capability according to claim 2, characterized in that: The lower surface of the lower rotor (31) is attached with a magnet (34) for attracting the upper rotor (33).

4. The ultrasonic micromotor module with improved driving capability according to claim 2, characterized in that: The rotating shaft (32) has a straight cut (321) on its side, and the upper rotor (33) has a through hole (331). The side of the through hole (331) has a straight flange (332). The rotating shaft (32) and the upper rotor (33) are in clearance fit, and the straight cut (321) of the rotating shaft (32) and the straight flange (332) of the upper rotor (33) are in fit.

5. The ultrasonic micromotor module with improved driving capability according to claim 1, characterized in that: The protrusions (21) on the upper surface of the ultrasonic micromotor stator structure (2) and the protrusions (21) on the lower surface of the ultrasonic micromotor stator structure (2) are arranged facing each other.

6. The ultrasonic micromotor module with improved driving capability according to claim 1, characterized in that: The ultrasonic micromotor stator structure (2) includes an annular elastic substrate (22). Several piezoelectric thin film components (23) are arranged on the upper and lower sides of the elastic substrate (22) along the circumferential direction. The several piezoelectric thin film components (23) on the upper side and the several piezoelectric thin film components (23) on the lower side are offset by half an angle from a single piezoelectric thin film component (23) on the circumference. The driving signal loaded on the several piezoelectric thin film components (23) on the same side changes phase equally along the circumferential direction.

7. An ultrasonic micromotor module with improved driving capability according to claim 6, characterized in that: The piezoelectric thin film assembly (23) includes a lower electrode (231), a piezoelectric thin film (232) and an upper electrode (233) arranged in sequence. The lower electrode (231) is grown on the surface of the elastic substrate (22), the driving signal is applied to the upper electrode (233), and the lower electrode (231) is grounded.

8. An ultrasonic micromotor module with improved driving capability according to claim 7, characterized in that: On the elastic substrate (22), several upper electrodes (233) on the same side are sequentially and cyclically loaded with driving signals of phases sin, cos, -sin, and -cos along the circumferential direction.

9. An ultrasonic micromotor module with improved driving capability according to claim 6, characterized in that: The elastic base (22) has a central hole (221) in the middle, the rotating shaft (32) passes through the central hole (221), and the edge of the elastic base (22) is evenly arranged with arc-shaped teeth (222).

10. An ultrasonic micromotor module with improved driving capability according to claim 6, characterized in that: The material of the elastic substrate (22) is one of monocrystalline silicon, ceramic, polyimide, PDMS, stainless steel, copper alloy, and iron-nickel alloy.

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