Stroke detection device of threaded piezoelectric actuator

Abstract

The utility model belongs to the technical field of stroke detection of driving elements, and particularly relates to a stroke detection device of a thread piezoelectric actuator, which comprises a sliding seat integrated in the thread piezoelectric actuator, and the sliding seat is configured to rotate relative to a screw rod and can synchronously move along with the screw rod along the axial direction of the screw rod; a limiting assembly is arranged between the sliding base and the base and can prevent the sliding base from rotating relative to the base. The reading head and the encoder are oppositely arranged. According to the utility model, through arranging the sliding seat which is rotatably connected with the screw rod and slidably connected with the base and prevents rotation through the limiting assembly, the composite motion of the screw rod is decomposed into pure axial translation of the sliding seat relative to the base, and the reading head and the encoder are respectively arranged on the sliding seat and the base or the screw rod and the sliding seat, so that the closed-loop control of the thread piezoelectric actuator is realized; and the driving precision and the long-term reliability under various loads and working conditions are obviously improved.

Description

Technical Field

[0001] This utility model belongs to the field of drive element stroke detection technology, specifically relating to a stroke detection device for a threaded piezoelectric actuator. Background Technology

[0002] Threaded piezoelectric actuators are mainly used in optical precision adjustment, semiconductor manufacturing equipment, micro-nano manipulation, aerospace, and other fields. Threaded piezoelectric actuators utilize the inverse piezoelectric effect of piezoelectric ceramics. By generating micro-amplitude expansion and contraction under an alternating electric field, the internal precision thread mechanism converts the minute reciprocating vibrations of the piezoelectric device into the rotational motion of the screw. The threaded pair then achieves macroscopic, large-stroke, high-precision linear displacement. Traditional threaded piezoelectric actuators use open-loop control, and their working principle is to infer displacement based on the frequency and voltage of the drive signal. However, the inherent hysteresis, creep, and nonlinear characteristics of piezoelectric ceramics cause deviations between the actual displacement and the theoretical value. Furthermore, the transmission efficiency between the piezoelectric device and the screw is extremely sensitive to load changes and friction conditions. Any slight fluctuation in the load directly leads to inconsistent stepping efficiency, resulting in accumulated errors. Therefore, in applications requiring high repeatability or long-term stability, the driving accuracy and reliability are difficult to guarantee. Utility Model Content

[0003] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a stroke detection device for a threaded piezoelectric actuator that can improve the motion accuracy of the threaded piezoelectric actuator.

[0004] To achieve the above and other related objectives, this utility model provides a stroke detection device for a threaded piezoelectric actuator, the threaded piezoelectric actuator including a base, a screw threadedly engaged with the base, and a piezoelectric driving element for driving the screw to rotate;

[0005] The stroke detection device includes components integrated within the threaded piezoelectric actuator:

[0006] A slide block, connected to the screw, is configured to rotate relative to the screw and to move synchronously with the screw along the axial direction of the screw;

[0007] A limiting component is provided between the slide and the base. The limiting component is configured to prevent the slide from rotating relative to the base when the slide moves synchronously with the screw along the axial direction of the screw.

[0008] It also includes a reading head and an encoder arranged opposite to each other, one of which is disposed on the slide and the other on the base, or one of which is disposed on the screw and the other on the slide.

[0009] In an optional embodiment of this utility model, in response to one of the reading head and the encoder being disposed on the slide and the other being disposed on the base, the encoder is elongated and the length direction of the encoder is parallel to the axial direction of the screw.

[0010] In an optional embodiment of this utility model, in response to one of the reading head and the encoder being disposed on the screw and the other being disposed on the slide, the encoder is annular and the axis of the encoder is collinear with the axis of the screw.

[0011] In an optional embodiment of this utility model, the encoder is fixedly connected to the screw, and the reading head is fixedly connected to the slide.

[0012] In an optional embodiment of this utility model, the limiting component includes a linear guide portion and a guided portion that is slidably disposed along the linear guide portion. One of the linear guide portion and the guided portion is disposed on the base, and the other is disposed on the slide block. The length direction of the linear guide portion is parallel to the axial direction of the screw.

[0013] In an optional embodiment of this utility model, the linear guide portion includes a guide rail that is detachably fixedly connected to the base, and the guided portion includes a slider that is fixedly connected to the slide block, and the slider is slidably connected to the guide rail.

[0014] In an optional embodiment of this utility model, the base is provided with a positioning part for limiting the installation angle of the guide rail. The positioning part includes a positioning surface arranged along the axial direction of the screw, and one side of the guide rail abuts against the positioning surface.

[0015] In an optional embodiment of this utility model, the slide is circumferentially rotatable and axially fixedly connected to the screw via a bearing.

[0016] In an optional embodiment of the present invention, a controller is further included. The detection signal output terminal of the reading head is electrically connected to the controller, and the controller is electrically connected to the drive signal receiving terminal of the piezoelectric drive element. The controller is configured to control the operation of the piezoelectric drive element according to the detection signal of the reading head.

[0017] In an optional embodiment of the present invention, the base includes a body and a cover, the cover being detachably fixedly connected to the body, the cover and the body enclosing each other to form at least one receiving portion, the slide, the limiting component, the reading head and the encoder being received within the receiving portion.

[0018] The technical advantages of this utility model are as follows: By setting a slide that is rotatably connected to the screw and slidably connected to the base and prevented from rotating by a limiting component, the complex motion of the screw is decomposed into a pure axial translation of the slide relative to the base. The reading head and the encoder are respectively set on the slide and the base or the screw and the slide, thus realizing closed-loop control of the threaded piezoelectric actuator and significantly improving its driving accuracy and long-term reliability under various loads and working conditions. Attached Figure Description

[0019] Figure 1 This is a perspective view of the threaded piezoelectric actuator provided in an embodiment of the present invention;

[0020] Figure 2 This is a cross-sectional view of the threaded piezoelectric actuator provided in the first embodiment of this utility model;

[0021] Figure 3 yes Figure 2 AA section view;

[0022] Figure 4 This is a cross-sectional view provided in the second embodiment of this utility model, and its cutting direction is... Figure 2 The direction indicated by BB in the diagram;

[0023] Figure 5 yes Figure 4 A magnified view of part of the I;

[0024] Figure 6 This is an exploded view of the limiting component provided in an embodiment of this utility model;

[0025] Figure 7 This is a schematic diagram illustrating the working principle of the stroke detection device provided in an embodiment of this utility model;

[0026] Explanation of reference numerals in the attached drawings: 100, threaded piezoelectric actuator; 10, base; 101, positioning part; 102, positioning surface; 11, body; 12, cover; 20, screw; 30, piezoelectric drive element; 40, slide; 50, limiting assembly; 51, linear guide; 52, guided part; 60, reading head; 70, encoder; 80, bearing. Detailed Implementation

[0027] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0028] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] Please see Figures 1 to 7 As shown, the stroke detection device provided by this utility model is applied to a threaded piezoelectric actuator 100. The threaded piezoelectric actuator 100 includes a base 10, a screw 20 threadedly engaged with the base 10, and a piezoelectric drive element 30 for driving the screw 20 to rotate. Unlike some external stroke detection devices (such as detection devices used to detect the motion stroke of a multi-degree-of-freedom platform when the threaded piezoelectric actuator 100 is applied), the stroke detection device of this utility model is integrated inside the threaded piezoelectric actuator 100, which can realize closed-loop feedback control of the threaded piezoelectric actuator 100 itself. This utility model detects the motion stroke at the power output source of the piezoelectric drive element 30, ensuring that the threaded piezoelectric actuator 100 can have relatively reliable driving accuracy in various application scenarios.

[0030] The working principle of the threaded piezoelectric actuator 100 is to first convert the vibration generated by the piezoelectric driving element 30 into the rotational motion of the screw 20, and then use the threaded pair between the screw 20 and the base 10 to convert the rotational motion of the screw 20 into the axial motion of the screw 20. Since the screw 20 itself has both circumferential rotation and axial translation, it is difficult for traditional stroke detection devices to find suitable detection benchmarks and installation points. This is also the reason why most threaded piezoelectric actuators 100 adopt open-loop control. However, open-loop control is difficult to guarantee reliable driving accuracy due to transmission errors. To address this, the stroke detection device provided by this invention uses a slide block 40 that is rotatably connected to the screw 20 and slidably connected to the base 10 to convert the combined rotational and translational motion of the screw 20 into a single relative translational motion or a single relative rotational motion, thereby achieving reliable detection of the screw 20's stroke and realizing closed-loop control of the threaded piezoelectric actuator 100, thus improving the driving accuracy of the threaded piezoelectric actuator 100.

[0031] The technical solution of this utility model will be described in detail below with reference to specific embodiments:

[0032] Please see Figures 2 to 6As shown, the stroke detection device provided by this utility model includes a slide 40, a limiting component 50, a reading head 60, and an encoder 70 integrated inside the threaded piezoelectric actuator 100. The slide 40 is connected to the screw 20 and is configured to rotate relative to the screw 20 and move synchronously with the screw 20 along the axial direction of the screw 20. A limiting component 50 is provided between the slide 40 and the base 10. The limiting component 50 is configured to prevent the slide 40 from rotating relative to the base 10 when the slide 40 moves synchronously with the screw 20 along the axial direction of the screw 20. The reading head 60 and the encoder 70 are arranged opposite to each other. One of the reading head 60 and the encoder 70 is disposed on the slide 40 and the other is disposed on the base 10, or one of the reading head 60 and the encoder 70 is disposed on the screw 20 and the other is disposed on the slide 40.

[0033] This invention, by setting a slide 40 that is rotatably connected to the screw 20 and slidably connected to the base 10 and prevented from rotating by a limiting component 50, decomposes the complex motion of the screw 20 into a pure axial translation of the slide 40 relative to the base 10. The reading head 60 and the encoder 70 are respectively positioned on the slide 40 and the base 10 or on the screw 20 and the slide 40, realizing closed-loop control of the threaded piezoelectric actuator 100, significantly improving its driving accuracy and long-term reliability under various loads and operating conditions. Specifically, the slide 40 and the limiting component 50 work together to transform the originally difficult-to-detect rotational and translational coupled motion of the screw 20 into a stable, single relative linear motion between the slide 40 and the base 10, or a relative rotational motion between the screw 20 and the slide 40. This provides a clear and stable measurement benchmark for stroke detection. Therefore, the encoder 70 can directly and accurately detect the actual displacement of the screw 20 at the drive source in real time, fundamentally overcoming the cumulative error problem caused by transmission efficiency fluctuations and the nonlinear characteristics of piezoelectric ceramics in traditional open-loop control.

[0034] Please see Figures 2 to 5As shown, in an optional embodiment of this utility model, in response to one of the reading head 60 and the encoder 70 being disposed on the slide 40 and the other on the base 10, the encoder 70 is elongated, and the length direction of the encoder 70 is parallel to the axial direction of the screw 20. In this optional embodiment, by setting the encoder 70 to be elongated and its length direction parallel to the axial direction of the screw 20, the continuity and integrity of the stroke detection are ensured, and errors introduced by insufficient measurement range are avoided, thereby providing a reliable length reference for realizing full-stroke, high-precision closed-loop feedback control. Specifically, the pure axial translational motion of the slide 40 relative to the base 10 is directly mapped to the measurement scale of the encoder 70. The elongated encoder 70, as a fixed axial scale, can completely cover the entire effective stroke of the slide 40, allowing the reading head 60 mounted on the slide 40 to continuously and uninterruptedly read position information during movement.

[0035] like Figure 2 , Figure 3 As shown, in some embodiments, the reading head 60 is mounted on the base 10, and the encoder 70 is mounted on the slide 40. This embodiment places the reading head 60, which requires connection to external signal lines, on the stationary base 10, while the encoder 70, which only requires optical or magnetic calibration, moves with the slide 40. This fundamentally simplifies the internal wiring of the device, avoiding the repeated bending, wear, and signal interference problems associated with arranging cables on moving parts. It greatly improves the reliability and lifespan of the wiring connections, while also making cable routing fixed and simple, reducing assembly difficulty and maintenance costs. Figure 4 As shown, in some other embodiments, if wiring complexity is not a concern, the reading head 60 can be mounted on the slide 40 and the encoder 70 can be mounted on the base 10.

[0036] In another optional embodiment of this utility model (not shown), in response to one of the reading head and the encoder being disposed on the screw and the other on the slide, the encoder is circular, and the axis of the encoder is collinear with the axis of the screw. In this optional embodiment, by coaxially distributing the circular encoder with the screw and separately distributing it and the reading head on the screw and slide, displacement detection is transformed into rotation angle detection, directly detecting the relative rotational motion between the screw and the slide. This fully utilizes the high-resolution advantage of the rotary encoder, achieving indirect high-precision measurement of nanometer-level linear displacement. Specifically, since the slide is restricted from rotation by the limiting component and can only translate axially, the rotation angle of the screw relative to the slide forms a strict, linear proportional relationship with the axial displacement of the screw through the lead relationship of the threaded pair. By measuring this relative rotation angle, the circular encoder can indirectly but accurately calculate the absolute axial displacement of the screw. In a preferred embodiment, the encoder is fixedly connected to the screw, and the reading head is fixedly connected to the slide. This embodiment fixes the encoder to the rotating screw and the reading head to a slide that only moves axially. This transforms the complex rotational wiring problem into simple linear wiring, significantly improving the reliability and lifespan of the circuit and reducing assembly difficulty. Specifically, associating the delicate and fragile reading head and its connecting cable with the relatively stable slide avoids the risk of cable entanglement and breakage caused by the high-speed rotation of the screw. Although the slide moves, its movement is purely linear; the cable only needs to undergo simple axial bending or be guided by a flexible cable chain, resulting in a fixed and reliable wiring path. It should be understood that, without considering wiring complexity, the reading head can also be mounted on the screw, and the encoder on the slide.

[0037] Please see Figures 2 to 6As shown, in an optional embodiment of the present invention, the limiting component 50 includes a linear guide portion 51 and a guided portion 52 slidably disposed along the linear guide portion 51. One of the linear guide portion 51 and the guided portion 52 is disposed on the base 10, and the other is disposed on the slide block 40. The length direction of the linear guide portion 51 is parallel to the axial direction of the screw 20. In this optional embodiment, by setting a limiting component 50 composed of a linear guide 51 and a guided part 52, and strictly limiting its guiding direction to be parallel to the axis of the screw 20, a high-precision and unique degree of freedom constraint is provided for the movement of the slide 40 relative to the base 10. This component effectively locks all radial and circumferential degrees of freedom of the slide 40, retaining only its translational degree of freedom along the axis of the screw 20, ensuring that the slide 40 can only perform pure, non-rotational linear motion, thereby establishing a stable and jitter-free measurement reference plane between the reading head 60 and the encoder 70, fundamentally eliminating detection errors caused by motion coupling or gaps, and ensuring high accuracy and reliability of the stroke detection results.

[0038] Please see Figure 5 , Figure 6 As shown, in an optional embodiment of this utility model, the linear guide 51 includes a guide rail that is detachably fixedly connected to the base 10, and the guided part 52 includes a slider that is fixedly connected to the slide block 40. The slider is slidably connected to the guide rail. The base 10 is provided with a positioning part 101 for limiting the installation angle of the guide rail. The positioning part 101 includes a positioning surface 102 arranged along the axial direction of the screw 20, and one side of the guide rail abuts against the positioning surface 102. In this optional embodiment, by providing a positioning part 101 with an axial positioning surface 102 on the base 10, and by detachably installing the guide rail with its side abutting against the positioning surface 102, it is ensured that the mounting axis of the guide rail is strictly parallel to the axis of the screw 20. This embodiment directly constrains the angular degree of freedom of the guide rail through the mechanical positioning surface 102, transforming the high-precision assembly relationship into a simple surface contact alignment. This effectively eliminates the problem of the guide direction not coinciding with the axis of the screw 20 due to installation deviations. This not only reduces the dependence on on-site installation accuracy and ensures the accuracy of the slide 40's movement trajectory, but also avoids additional bending moments and friction caused by non-parallel guides from the source, thereby ensuring the accuracy and long-term stability of the stroke detection benchmark. It should be understood that in some other embodiments, while ensuring installation accuracy, the guide rail can also be placed on the slide 40, and the slider can be placed on the base 10.

[0039] Please see Figure 2 , Figure 6As shown, in an optional embodiment of this utility model, the slide 40 is circumferentially rotated and axially fixedly connected to the screw 20 via a bearing 80. This optional embodiment connects the slide 40 and the screw 20 via the bearing 80, achieving precise decoupling of the motion. The inner and outer rings of the bearing 80 are fixed to the screw 20 and the slide 40 respectively. Utilizing the low-friction and high-precision rotational characteristics of the bearing 80, the rotational motion of the screw 20 can be decoupled from the slide 40 with almost no resistance; that is, the screw 20 can rotate freely while the slide 40 does not rotate with it. Simultaneously, the bearing 80 provides a rigid connection in the axial direction, ensuring that the axial displacement of the screw 20 can be transmitted to the slide 40 without hysteresis or gaps, thereby guaranteeing the accuracy and reliability of subsequent stroke detection.

[0040] Please see Figure 7 As shown, in an optional embodiment of this utility model, a controller is further included. The detection signal output terminal of the reading head 60 is electrically connected to the controller, and the controller is electrically connected to the drive signal receiving terminal of the piezoelectric drive element 30. The controller is configured to control the operation of the piezoelectric drive element 30 according to the detection signal of the reading head 60. This optional embodiment, by introducing a controller and establishing a closed-loop electrical connection between the controller, the reading head 60, and the piezoelectric drive element 30, transforms the direct displacement detection signal based on mechanical decoupling into real-time drive control commands. The controller dynamically adjusts the voltage, frequency, and other parameters applied to the piezoelectric drive element 30 by continuously comparing the actual displacement fed back by the reading head 60 with the target displacement, thereby actively compensating for errors caused by factors such as piezoelectric ceramic hysteresis, creep, nonlinearity, and transmission efficiency fluctuations. This closed-loop control mechanism transforms the speculative drive in the open-loop system into a feedback drive, fundamentally correcting the stroke deviation and ensuring that the drive can output high-precision and high-repeatability displacement under various loads and operating conditions.

[0041] Please see Figures 1 to 4As shown, in an optional embodiment of this utility model, the base 10 includes a body 11 and a cover 12. The cover 12 is detachably fixedly connected to the body 11. The cover 12 and the body 11 enclose at least one receiving portion, in which the slide 40, the limiting component 50, the reading head 60, and the encoder 70 are received. This optional embodiment, by setting the receiving portion formed by the body 11 and the detachable cover 12, constructs a closed physical barrier for the internal precision detection components. This embodiment isolates the core detection components such as the slide 40, the limiting component 50, the reading head 60, and the encoder 70 from the external environment, effectively preventing the intrusion of contaminants such as dust and oil, and avoiding their adhesion to the encoder 70 scale or the surface of the moving parts, which could lead to signal distortion, increased wear, or jamming. The detachability of the cover 12 balances sealing protection with ease of maintenance. While ensuring the protective effect, it facilitates the installation, debugging, and maintenance of internal components, thereby ensuring the long-term stable and reliable operation of the stroke detection system even in harsh industrial environments.

[0042] In summary, this utility model, by setting a slide block that is rotatably connected to the screw and slidably connected to the base and prevented from rotating by a limiting component, decomposes the compound motion of the screw into a pure axial translation of the slide block relative to the base. Furthermore, by setting the reading head and encoder separately on the slide block and the base or the screw and the slide block, it realizes closed-loop control of the threaded piezoelectric actuator, significantly improving its driving accuracy and long-term reliability under various loads and working conditions.

[0043] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

[0044] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.

Claims

1. A stroke detection device for a threaded piezoelectric actuator, the threaded piezoelectric actuator (100) comprising a base (10), a screw (20) threadedly engaged with the base (10), and a piezoelectric drive element (30) for driving the screw (20) to rotate. Its features are, The stroke detection device includes components integrated within the threaded piezoelectric actuator (100): A slide (40) is connected to the screw (20), the slide (40) being configured to rotate relative to the screw (20) and to move synchronously with the screw (20) along the axial direction of the screw (20); A limiting component (50) is provided between the slide (40) and the base (10). The limiting component (50) is configured to prevent the slide (40) from rotating relative to the base (10) when the slide (40) moves synchronously with the screw (20) along the axial direction of the screw (20). It also includes a reading head (60) and an encoder (70) arranged opposite to each other, one of the reading head (60) and the encoder (70) being disposed on the slide (40) and the other being disposed on the base (10), or one of the reading head and the encoder being disposed on the screw and the other being disposed on the slide.

2. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, In response to one of the reading head (60) and the encoder (70) being disposed on the slide (40) and the other being disposed on the base (10), the encoder (70) is elongated and the length direction of the encoder (70) is parallel to the axial direction of the screw (20).

3. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, In response to the fact that one of the reading head and the encoder is disposed on the screw and the other is disposed on the slide, the encoder is annular and the axis of the encoder is collinear with the axis of the screw.

4. The stroke detection device for the threaded piezoelectric actuator according to claim 3, characterized in that, The encoder is fixedly connected to the screw, and the reading head is fixedly connected to the slide.

5. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, The limiting component (50) includes a linear guide (51) and a guided part (52) slidably disposed along the linear guide (51). One of the linear guide (51) and the guided part (52) is disposed on the base (10) and the other is disposed on the slide (40). The length direction of the linear guide (51) is parallel to the axial direction of the screw (20).

6. The stroke detection device for the threaded piezoelectric actuator according to claim 5, characterized in that, The linear guide (51) includes a guide rail that is detachably fixedly connected to the base (10), and the guided part (52) includes a slider that is fixedly connected to the slide (40), and the slider is slidably connected to the guide rail.

7. The stroke detection device for the threaded piezoelectric actuator according to claim 6, characterized in that, The base (10) is provided with a positioning part (101) for limiting the installation angle of the guide rail. The positioning part (101) includes a positioning surface (102) arranged along the axial direction of the screw (20). One side of the guide rail abuts against the positioning surface (102).

8. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, The slide (40) is circumferentially rotated and axially fixedly connected to the screw (20) via a bearing (80).

9. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, It also includes a controller, the detection signal output terminal of the reading head (60) is electrically connected to the controller, the controller is electrically connected to the drive signal receiving terminal of the piezoelectric drive element (30), and the controller is configured to control the piezoelectric drive element (30) to operate according to the detection signal of the reading head (60).

10. The stroke detection device for the threaded piezoelectric actuator according to claim 1, characterized in that, The base (10) includes a body (11) and a cover (12). The cover (12) is fixedly connected to the body (11) in a detachable manner. The cover (12) and the body (11) enclose at least one receiving part. The slide (40), the limiting component (50), the reading head (60) and the encoder (70) are received in the receiving part.

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