Piezoelectric screw and its limiting structure

Abstract

The application discloses a piezoelectric screw and a limiting structure thereof, and belongs to the technical field of precise piezoelectric micro driving, which comprises a guide sleeve fixedly arranged relative to a mounting carrier and a screw rod axially penetrating through the guide sleeve and threadedly matched with the guide sleeve; further comprising: a first stop portion synchronously rotating with the screw rod; a limiting protrusion fixedly arranged relative to the mounting carrier, and the limiting protrusion extending to a rotating path of the first stop portion; when the screw rod is in a first axial limit position, a first end surface of the limiting protrusion abuts against the first stop portion to prevent the screw rod from rotating and feeding in a first direction; by arranging the first stop portion and a second stop portion on a screw cap and fixing the limiting protrusion relative to the mounting carrier, the stroke of the screw rod can be limited along the axial direction of the screw rod, the structure does not need to additionally arrange a limiting component on the screw rod body, the diameter of the screw rod is not increased, and the structure is more suitable for installation and use in a narrow space.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric screw technology, and particularly to a precision piezoelectric micro-drive technology. Background Technology

[0002] Piezoelectric-driven precision screws are core actuators in precision positioning and micro / nano adjustment fields, widely used in applications such as optical focusing, precision instruments, microelectronic packaging, and biomedical manipulation where stringent requirements for displacement accuracy and structural dimensions are present. Existing piezoelectric-driven rotary / linear actuators mostly employ piezoelectric stack deformation to drive the stator frame, using the stick-slip motion principle to rotate the screw. The rotary motion is then converted into linear feed motion through a threaded pair, offering advantages such as fast response, high resolution, no electromagnetic interference, and compact structure.

[0003] Patent CN107636951A discloses a piezoelectric rotary actuator for a shaft, which uses a piezoelectric actuator in conjunction with a deformable frame to achieve stick-slip drive and uses a leaf spring as a preload device. The structure is convenient for production and assembly. However, this solution focuses on rotary drive and does not have a reliable limit design for the linear feed stroke of the screw. Over-travel impact and positioning failure are likely to occur after long-term use.

[0004] Chinese patent CN223928243U discloses a linear motor-type electric screw, which uses a flexible hinge, piezoelectric ceramic, and preload spring to form a drive mechanism. This mechanism clamps the screw to achieve rotation and linear motion, with axial positioning relying on a stop nut. However, this design has shortcomings in practical applications: the stop nut directly contacts the housing structure for rigid positioning, and repeated impacts can easily cause plastic deformation at the contact point, resulting in positional deviation and decreased stroke accuracy. Furthermore, the stop nut's rigid end-face contact positioning lacks a reliable rotational positioning structure, making it prone to jamming and wear over time, and also increasing radial dimensions, hindering miniaturization design.

[0005] Therefore, it is necessary to provide a piezoelectric screw and its limiting structure to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a piezoelectric screw and its limiting structure to solve the technical problems mentioned in the background art.

[0007] Based on the above ideas, the present invention provides the following technical solution: a limiting structure for a piezoelectric screw, comprising a guide sleeve fixedly disposed relative to a mounting carrier and a screw threadedly disposed through the guide sleeve along its axial direction and threadedly engaged therewith; further comprising: The first stop rotates synchronously with the screw. A limiting protrusion is fixedly disposed relative to the mounting carrier, and the limiting protrusion extends to the rotation path of the first stop portion; When the screw is at the first axial limit position, the first end face of the limiting protrusion abuts against the first stop portion to prevent the screw from rotating and feeding in the first direction.

[0008] As a further aspect of the present invention, it also includes: The second stop is provided in pair with the first stop; When the screw is at the second axial limit position, the second end face of the limiting protrusion abuts against the second stop portion to prevent the screw from rotating and feeding in the second direction.

[0009] As a further aspect of the present invention: the first stop portion and the second stop portion are spaced apart along the axis parallel to the screw, and a clearance groove is formed between them for the limiting protrusion to rotate through. During the entire process of the screw rotating from the first axial limit position to the second axial limit position, the limiting protrusion passes through the clearance groove at least once.

[0010] As a further aspect of the present invention: along a direction parallel to the screw axis, the width of the limiting protrusion is adapted to the distance fed by the screw in one revolution.

[0011] As a further aspect of the present invention: the screw end is provided with a nut, and the first stop portion and the second stop portion are both plate-shaped structures extending outward along the diameter direction of the nut or parallel to the diameter direction of the nut.

[0012] As a further aspect of the present invention: the first stop portion and the second stop portion are symmetrically arranged about the center of the nut axis.

[0013] As a further aspect of the present invention: both the first stop portion and the second stop portion are integrally formed on the connector, and the connector is fixedly connected to the nut.

[0014] As a further aspect of the present invention, a gasket is provided between the connector and the nut.

[0015] As a further aspect of the present invention: the limiting protrusion is integrally formed on the limiting member, so that the limiting protrusion is fixedly positioned relative to the mounting carrier through the limiting member.

[0016] A piezoelectric screw, including the limiting structure of the piezoelectric screw described above; A stator frame is provided on the outside of the screw. The stator frame has a circumferential part and a frame leg. The circumferential part and the frame leg are connected by a flexible hinge. The circumferential part fits against the outer circular surface of the screw. A piezoelectric stack is installed between the frame leg and the circumferential part.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting the first stop and the second stop on the nut and fixing the limiting protrusion relative to the mounting carrier, the stroke of the screw can be limited along the axis of the screw. This structure does not require adding limiting components to the screw body, does not increase the screw diameter, and is more suitable for installation in confined spaces; at the same time, it can prevent the limiting components from deforming during long-term use, which is beneficial to improving the limiting accuracy and working stability. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram of the structure in which the first stop and the second stop are integrally formed on the connector of the present invention; Figure 2 This is a schematic diagram of the structure in which the first stop and the second stop of the present invention are respectively formed on the connector; Figure 3 This is a schematic diagram showing the position of the limiting protrusion entering the clearance groove of the present invention; Figure 4 This is a schematic diagram showing the position of the limiting protrusion abutting against the second stop portion of the present invention; Figure 5 This is a schematic diagram showing the first stop portion and the second stop portion of the present invention arranged symmetrically about the center of the nut axis; Figure 6 This is a schematic diagram of the internal structure of the outer shell of the present invention; Figure 7 This is a top view of the stator frame and screw assembly of the present invention; Figure 8 This is a three-dimensional structural diagram of the stator frame of the present invention; Figure 9 This is a three-dimensional structural diagram of the limiting component of the present invention.

[0020] In the diagram: 1. Outer shell; 2. Screw; 201. Nut; 3. Guide sleeve; 4. Connector; 5. Limiting protrusion; 501. First end face; 502. Second end face; 6. Limiting component; 601. First fixing part; 602. Second fixing part; 603. Bending part; 7. First stop part; 8. Second stop part; 9. Stator frame; 901. Encircling part; 902. Frame support leg; 903. Flexible hinge; 10. Annular grating; 11. Piezoelectric stack; 12. Clearance groove; 13. Leaf spring. Detailed Implementation

[0021] like Figures 1-9As shown, a piezoelectric screw and its limiting structure include a screw 2 and a guide sleeve 3 sleeved on the outside of the screw 2; the section of the screw 2 located inside the guide sleeve 3 is provided with external threads (the rest of the screw 2 can be a smooth rod structure), so that the screw 2 can move linearly along the axis of the guide sleeve 3 when it rotates relative to the guide sleeve 3.

[0022] like Figure 3 As shown, a pressing head is fixed at one end of the screw 2. The end of the pressing head adopts a crown-shaped structure, which can effectively reduce the wear generated when pushing the workpiece for a long time.

[0023] The screw 2 is provided with a stator frame 9 on its outer side. The stator frame 9 has a circumferential part 901 that cooperates with the screw 2. The circumferential part 901 can be set as a C-shaped structure and the arc length of the contact with the outer circle of the screw 2 is greater than half of the outer circumference of the screw 2, so as to ensure that a stable static friction fit is formed between the circumferential part 901 and the screw 2.

[0024] The stator frame 9 is provided with frame legs 902, which are connected to the circumferential portion 901 via flexible hinges 903. A piezoelectric stack 11 is installed between the frame legs 902 and the circumferential portion 901. Applying a control voltage to the piezoelectric stack 11 causes it to deform along the tangential or approximately tangential direction of the screw 2, thereby driving the circumferential portion 901 to deflect around the flexible hinges 903.

[0025] During operation, an asymmetric voltage waveform is used for driving: within one cycle, the voltage rises slowly, causing the piezoelectric stack 11 to elongate at a uniform speed. At this time, the retaining part 901 drives the screw 2 to rotate through static friction. The screw 2 and the guide sleeve 3 are threaded together to achieve axial feed. When the voltage drops rapidly, the piezoelectric stack 11 retracts quickly, and the screw 2 maintains its original rotational tendency under the action of inertia. The retaining part 901 and the screw 2 slide relative to each other. By periodically applying the driving voltage, continuous rotation of the screw 2 and continuous axial feed can be achieved.

[0026] To ensure a reliable fit between the retaining portion 901 and the screw 2, a leaf spring 13 is engaged between the extensions a at both ends of the stator frame 9. The leaf spring 13 applies an outward pulling force to the two sets of extensions a and provides an inward pressing force to the retaining portion 901, so that the retaining portion 901 is always tightly abutting against the outer circumferential surface of the screw 2.

[0027] An annular grating 10 is sleeved on the outside of the screw 2. The annular grating 10 is circumferentially fixed to the screw 2 and can rotate synchronously with the screw 2. A reading head is provided below the annular grating 10 to detect the rotation angle of the annular grating 10 in real time, thereby realizing high-precision closed-loop control of the feed displacement of the screw 2.

[0028] The aforementioned drive and closed-loop detection structures are all existing mature technologies, and their specific details and working principles will not be elaborated here. This solution mainly optimizes the axial limiting structure of screw 2, as follows: The stator frame 9, leaf spring 13, reading head, and annular grating 10 are all installed inside the housing 1. One end of the housing 1 is open, and the opening is sealed by a pressure cap. The pressure cap and the housing 1 can be connected and fixed by interference fit, adhesive, or screw fastening.

[0029] Both the gland and the outer casing 1 have through holes for the screw 2 to pass through and be installed. It should be noted that the guide sleeve 3 is fixed to the mounting carrier, which can be the outer casing 1 or the mounting end face of an external device.

[0030] The screw 2 is provided with a nut 201 at one end extending out of the outer shell 1. The nut 201 can increase the rotational inertia of the screw 2, ensuring that the screw 2 can stably maintain its original rotational motion state when the piezoelectric stack 11 retracts rapidly.

[0031] Currently, limiting structures typically assemble a nut at the end of the screw 2, achieving bidirectional limiting through direct contact between the nut and the end face of the guide sleeve 3, and between the nut 201 and the end face of the outer shell 1. However, in practical applications, the guide sleeve 3 is often made of copper, and the outer shell 1 has a relatively thin wall thickness. Long-term repeated impacts can easily cause deformation of the guide sleeve 3 and the outer shell 1, thereby reducing the axial limiting accuracy of the screw 2.

[0032] Therefore, in this solution, a limiting protrusion 5 is fixedly installed on the mounting carrier (the housing 1 or the mounting end face of the external device) by screws, and a first stop 7 is provided at the screw 2. The first stop 7 is a plate-shaped structure that extends outward along the direction parallel to the diameter of the nut 201. The first stop 7 can rotate with the screw 2, and the side of the limiting protrusion 5 near the first stop 7 extends into the rotation path of the first stop 7, so that the cooperation between the first stop 7 and the limiting protrusion 5 can restrict the rotational feed of the screw 2 along the first direction (one direction along the axis of the screw 2).

[0033] Furthermore, a second stop 8 is fixedly provided relative to the mounting carrier. The second stop 8 is a plate-shaped structure extending outward along the direction parallel to the diameter of the nut 201. The cooperation between the second stop 8 and the limiting protrusion 5 can restrict the rotational feed of the screw 2 in the second direction (the other direction along the axis of the screw 2). The first stop 7 and the second stop 8 can be provided with clearance grooves 12 along the axis of the screw 2.

[0034] Combination Figures 2-4 As shown: Initially, the first end face 501 of the limiting protrusion 5 abuts against the first stop part 7, so that the screw 2 is in the first axial limit position. When the screw 2 drives the first stop part 7 to rotate approximately one revolution so that the first stop part 7 returns to the limiting protrusion 5, the limiting protrusion 5 can enter the relief groove 12. During the process of screw 2 driving the first stop 7 and the second stop 8 to rotate, the limiting protrusion 5 passes through the clearance groove 12 at least once. When the limiting protrusion 5 moves axially relative to the relief groove 12 to the limit position and the screw 2 drives the second stop part 8 to rotate approximately one revolution and return to the limiting protrusion 5, the second end face 502 of the limiting protrusion 5 can abut against the second stop part 8, thereby preventing the screw 2 from axially feeding and causing the screw 2 to be in the second axial limit position.

[0035] It should be noted that the width of the limiting protrusion 5 is adapted to the feed distance of one revolution of the screw 2. Specifically, the width of the limiting protrusion 5 is greater than or equal to the feed distance of one revolution of the screw 2, so that when the limiting protrusion 5 moves axially to the limit position of the relief groove 12 and the screw 2 continues to rotate one revolution, the limiting protrusion 5 can abut against the first stop part 7 or the second stop part 8.

[0036] In summary, the axial feed of the screw 2 can be reliably limited by the cooperation of the first stop 7, the second stop 8, and the limiting protrusion 5. Compared with the traditional limiting structure set at the end of the screw, this solution is more conducive to the miniaturization of the screw 2, thereby improving its operational adaptability.

[0037] Combination Figure 4 As shown, in one embodiment, the first stop portion 7 and the second stop portion 8 are integrally formed on the connecting member 4, from Figure 4 It can be seen that the first stop part 7 and the second stop part 8 are fixedly connected to the nut 201 through the connecting member 4.

[0038] Combination Figure 1 As shown, in another embodiment, the first stop 7 and the second stop 8 are simultaneously formed on the connector 4. Specifically, they can be produced by stamping and bending, which saves materials. However, the overall structural rigidity is less than that of the previous embodiment.

[0039] It should be noted that a shim can be provided between the connector 4 and the nut 201 to adjust the distance between the first stop 7 and the second stop 8, thereby facilitating the control of the axial limit stroke distance of the screw 2.

[0040] Combination Figure 5 As shown, the first stop portion 7 and the second stop portion 8 are symmetrically arranged about the axis of the nut 201, which can ensure that the rotational inertia of the nut 201 is uniform.

[0041] The limiting protrusion 5 can be integrally formed on the limiting member 6, so that the limiting protrusion 5 is fixed to the mounting carrier through the limiting member 6. The limiting protrusion 5 can be a flat head or a round head, etc.

[0042] Combination Figures 2-4 , Figure 9 As shown, the limiting member 6 is provided with a first fixing part 601 and a second fixing part 602. The first fixing part 601 can be fixed to the side wall of the outer shell 1, while the second fixing part 602 can be fixed at the lower position of the outer shell 1, so that the limiting member 6 is stably connected to the outer shell 1.

[0043] Furthermore, both the first fixing part 601 and the second fixing part 602 can have through holes, so that the first fixing part 601 and the second fixing part 602 can be fixed to the outer shell 1 by screws.

[0044] from Figure 9 As can be seen, the limiting member 6 is provided with a curved part 603, which is bent toward the nut 201. When the limiting groove is provided on the limiting member 6, it is located at the curved part 603.

[0045] The above-disclosed examples are merely preferred embodiments of this application, intended to facilitate understanding and implementation by those skilled in the art. However, they cannot be used to limit the scope of this application. Therefore, equivalent variations made within the scope of this application are still within the scope of this application.

Claims

1. A limiting structure for a piezoelectric screw, comprising a guide sleeve (3) fixedly disposed relative to a mounting carrier and a screw (2) axially extending through the guide sleeve (3) and threadedly engaged therewith; characterized in that, Also includes: The first stop (7) rotates synchronously with the screw (2); The limiting protrusion (5) is fixedly disposed relative to the mounting carrier, and the limiting protrusion (5) extends to the rotation path of the first stop (7); When the screw (2) is in the first axial limit position, the first end face (501) of the limiting protrusion (5) abuts against the first stop (7) to prevent the screw (2) from rotating and feeding in the first direction; Also includes: The second stop (8) is provided in pair with the first stop (7); When the screw (2) is in the second axial limit position, the second end face (502) of the limiting protrusion (5) abuts against the second stop (8) to prevent the screw (2) from rotating and feeding in the second direction; The first stop (7) and the second stop (8) are spaced apart along a direction parallel to the axis of the screw (2), and a clearance groove (12) is formed between them for the limiting protrusion (5) to rotate through. During the entire process of the screw (2) rotating from the first axial limit position to the second axial limit position, the limiting protrusion (5) passes through the clearance groove (12) at least once.

2. The limiting structure for a piezoelectric screw according to claim 1, characterized in that: Along the direction parallel to the axis of the screw (2), the width of the limiting protrusion (5) is adapted to the distance fed by the screw (2) in one revolution.

3. The limiting structure for a piezoelectric screw according to claim 1, characterized in that: The screw (2) is provided with a nut (201) at its end. The first stop (7) and the second stop (8) are both plate-shaped structures that extend outward along the diameter direction of the nut (201) or parallel to the diameter direction of the nut (201).

4. The limiting structure for a piezoelectric screw according to claim 3, characterized in that: The first stop (7) and the second stop (8) are symmetrically arranged about the axis of the nut (201).

5. The limiting structure for a piezoelectric screw according to claim 3, characterized in that: The first stop (7) and the second stop (8) are both integrally formed on the connector (4), and the connector (4) is fixedly connected to the nut (201).

6. The limiting structure for a piezoelectric screw according to claim 5, characterized in that: A gasket is provided between the connector (4) and the nut (201).

7. The limiting structure for a piezoelectric screw according to claim 1, characterized in that: The limiting protrusion (5) is integrally formed on the limiting member (6), so that the limiting protrusion (5) is fixedly set relative to the mounting carrier through the limiting member (6).

8. A piezoelectric screw, characterized in that: The limiting structure of the piezoelectric screw according to any one of claims 1 to 7; The screw (2) is provided with a stator frame (9) on the outside. The stator frame (9) has a circumferential part (901) and a frame leg (902). The circumferential part (901) and the frame leg (902) are connected by a flexible hinge (903). The circumferential part (901) is in contact with the outer circular surface of the screw (2). A piezoelectric stack (11) is installed between the frame leg (902) and the circumferential part (901).

Images