Limiting structure and piezoelectric screw

Abstract

This invention discloses a limiting structure and a piezoelectric screw, belonging to the field of precision piezoelectric micro-drive technology. It includes a guide sleeve fixedly disposed relative to a mounting carrier and a screw threadedly disposed along the axial direction of the guide sleeve; it also includes: a limiting protrusion that rotates synchronously with the screw; and a first stop portion fixedly disposed relative to the mounting carrier, extending along the rotation path of the limiting protrusion. When the screw is at a first axial limit position, the first end face of the limiting protrusion abuts against the first stop portion to prevent the screw from rotating in a first direction. By setting the limiting protrusion on the nut and fixing the first and second stops relative to the mounting carrier, the travel of the screw can be limited along its axial direction. This structure eliminates the need for additional limiting components on the screw body, does not increase the screw diameter, and is more suitable for installation in confined spaces.

Description

Technical Field

[0001] This invention relates to the field of precision piezoelectric micro-drive technology, and in particular to a limiting structure and a piezoelectric screw. 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] Invention 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 limiting structure and a piezoelectric screw to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a limiting structure and a piezoelectric screw 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 limiting protrusion rotates synchronously with the screw. The first stop portion is fixedly disposed relative to the mounting carrier, and the first stop portion extends to the rotation path of the limiting protrusion; 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: a second stop portion is provided in pair with the first stop portion; 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 a direction parallel to the screw axis, 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 widths of the first stop portion and the second stop portion are both adapted to the feed distance of one revolution of the screw.

[0011] As a further aspect of the present invention: the screw end is provided with a nut, and the limiting protrusion is a plate-like structure 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 limiting protrusion is fixedly connected to the outer circumferential surface of the nut.

[0013] As a further aspect of the present invention: the limiting protrusion is integrally formed on the connector, and the connector is fixedly connected to the nut.

[0014] As a further aspect of the present invention: the number of the limiting protrusions is at least one; when the number of the limiting protrusions is multiple, the mid-planes of the multiple limiting protrusions are coplanar and the multiple limiting protrusions are symmetrically distributed about the axis center of the nut.

[0015] 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.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting the limiting protrusion on the nut and fixing the first stop and the second stop 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 avoid deformation of the limiting components during long-term use, which is beneficial to improving the limiting accuracy and working stability. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram showing the position of the limiting protrusion abutting against the first stop portion of the present invention; Figure 2 This is a schematic diagram showing the position of the limiting protrusion entering the clearance groove of the present invention; Figure 3 This is a schematic diagram showing the position of the limiting protrusion abutting against the second stop portion of the present invention; Figure 4 This is a schematic diagram of the structure of the present invention, in which the limiting protrusion is a double protrusion; Figure 5 This is a schematic diagram showing the physical arrangement of the first stop portion and the second stop portion of the present invention; Figure 6 This is a schematic diagram showing the cooperation between the limiting protrusion of the present invention and the second stop in the split structure; Figure 7 This is a schematic diagram showing that the first stop portion and the second stop portion of the present invention are in a coplanar state on opposite sides; Figure 8 This is a schematic diagram of the internal structure of the outer shell of the present invention; Figure 9 This is a top view of the stator frame and screw assembly of the present invention; Figure 10 This is a three-dimensional structural diagram of the stator frame of the present invention; Figure 11 This is a three-dimensional structural diagram of the limiting component of the present invention.

[0019] In the diagram: 1. Outer shell; 101. Pressure cap; 2. Screw; 201. Nut; 202. Extrusion head; 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

[0020] like Figures 1-11 As shown, a limiting structure and a piezoelectric screw 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.

[0021] like Figure 2 As shown, a pressing head 202 is fixedly provided at one end of the screw 2. The end of the pressing head 202 adopts a crown-shaped structure, which can effectively reduce the wear generated when pushing the workpiece for a long time.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 101. The pressure cap 101 and the housing 1 can be connected and fixed by interference fit, adhesive, or screw fastening.

[0028] Both the pressure cap 101 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.

[0029] 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.

[0030] 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.

[0031] Therefore, this solution has a first stop 7 fixedly installed on the mounting carrier (the mounting surface of the outer shell 1 or the external device) by screws, and a limiting protrusion 5 is provided at the screw 2. The limiting protrusion 5 can rotate with the screw 2, and the side of the first stop 7 near the limiting protrusion 5 extends into the rotation path of the limiting protrusion 5, so that the cooperation between the first stop 7 and the limiting protrusion 5 can restrict the rotational feed of the screw 2 in the first direction (one direction along the axis of the screw 2); correspondingly, the nut 201 can be used to limit the screw in another direction by contacting the end face of the outer shell 1.

[0032] Furthermore, a second stop 8 is provided in the rotation path of the limiting protrusion 5 to cooperate with the first stop 7. It can be understood that the second stop 8 is also fixed relative to the mounting carrier. 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).

[0033] Combination Figure 3 , Figure 7As shown, the opposing surfaces of the first stop portion 7 and the second stop portion 8 are coplanar. Initially, the limiting protrusion 5 is in the first axial limit position. At this time, the first end face 501 of the limiting protrusion 5 contacts the first stop portion 7 to restrict the axial feed of the screw 2 along the first direction. When the screw 2 drives the limiting protrusion 5 to rotate nearly one revolution so that the second end face 502 of the limiting protrusion 5 abuts against the second stop portion 8, the screw 2 is in the second axial limit position. At this time, the contact between the second end face 502 of the limiting protrusion 5 and the second stop portion 8 can restrict the axial feed of the screw 2 along the second direction.

[0034] Of course, in order to increase the axial feed stroke of the screw 2, the first stop 7 and the second stop 8 can be provided with clearance grooves 12 in a direction parallel to the axis of the screw 2, such as... Figure 4 As shown, the axial feed stroke of the screw 2 can be controlled by changing the width of the clearance groove 12.

[0035] Combination Figures 1-3 As shown: Initially, the first end face 501 of the limiting protrusion 5 abuts against the first stop portion 7, so that the screw 2 is in the first axial limit position. In this state, when the screw 2 drives the limiting protrusion 5 to rotate approximately one revolution so that the limiting protrusion 5 returns to the first stop portion 7, the limiting protrusion 5 can enter the relief groove 12. During the process of the screw 2 driving the limiting protrusion 5 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 limiting protrusion 5 to rotate approximately one revolution and return to the second stop 8, the second end face 502 of the limiting protrusion 5 can abut against the second stop 8, thereby preventing the screw 2 from axially feeding and causing the screw 2 to be in the second axial limit position.

[0036] It should be noted that the widths of the first stop 7 and the second stop 8 are both adapted to the feed distance of one revolution of the screw 2. Specifically, the widths of the first stop 7 and the second stop 8 are both 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 clearance groove 12 and the screw 2 continues to rotate one revolution, the limiting protrusion 5 can abut against the first stop 7 or the second stop 8.

[0037] In one embodiment, both the first stop 7 and the second stop 8 are integrally formed on the limiting member 6, which is fixed to the mounting end face of the housing 1 or external equipment. In actual production, the limiting member 6 can be manufactured by stamping and bending, with the first stop 7 and the second stop 8 respectively on either side of the end of the limiting member 6 with the slot. This method saves materials during production and facilitates the rapid installation of the first stop 7 and the second stop 8.

[0038] In another embodiment, the first stop portion 7 and the second stop portion 8 are respectively integrally formed on the limiting member 6, such as Figure 5 As shown, the first stop 7 and the second stop 8 are separately configured and installed independently. Compared to the previous embodiment, the installation steps of the first stop 7 and the second stop 8 in this solution are more complicated. However, the width of the clearance groove 12 between the first stop 7 and the second stop 8 is easy to adjust, which is beneficial for adjusting the axial feed stroke range of the screw 2 and adapting to different installation requirements.

[0039] The limiting protrusion 5 is a plate-like structure extending outward along the diameter direction of the nut 201. In one embodiment of the limiting protrusion 5, the number of limiting protrusions 5 can be set to a single one, and the limiting protrusion 5 can be fixed to the outer circular surface of the nut 201 or integrally formed on the connector 4, and then fixed to the end of the nut 201 by the connector 4.

[0040] In another embodiment of the limiting protrusion 5, the number of the limiting protrusion 5 is set to multiple. Preferably, the number of limiting protrusions 5 is set to two. That is, the limiting protrusion 5 includes a first protrusion and a second protrusion ( Figure 4 (as shown in a1 and a2). (Refer to...) Figure 4 As shown, in this embodiment, the first protrusion and the second protrusion are arranged symmetrically about the axis of the nut 201. The mid-plane surfaces of the first protrusion and the second protrusion are coplanar and have equal thickness, which ensures that the rotational inertia of the nut 201 is uniform. It should be noted that the first end face 501 and the second end face 502 can be uniformly disposed at the first protrusion or the second protrusion, or disposed along the circumference of the nut 201 on the side opposite to the first protrusion and the second protrusion.

[0041] Combination Figure 2 , Figure 11As 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 to the lower position of the outer shell 1, so that the limiting member 6 is stably connected to the outer shell 1. Furthermore, both the first fixing part 601 and the second fixing part 602 can be provided with through round holes, so that the first fixing part 601 and the second fixing part 602 can be fixed to the outer shell 1 by screws.

[0042] from Figure 11 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.

[0043] 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 engaging therewith; characterized in that, Also includes: The limiting protrusion (5) rotates synchronously with the screw (2); The first stop (7) is fixedly disposed relative to the mounting carrier, and the first stop (7) extends to the rotation path of the limiting protrusion (5); 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.

2. The limiting structure for a piezoelectric screw according to claim 1, characterized in that, 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.

3. The limiting structure for a piezoelectric screw according to claim 2, characterized in that: 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.

4. The limiting structure for a piezoelectric screw according to claim 3, characterized in that: Along the direction parallel to the axis of the screw (2), the widths of the first stop (7) and the second stop (8) are both adapted to the distance fed by the screw (2) in one revolution.

5. The limiting structure for a piezoelectric screw according to claim 2, characterized in that: The screw (2) is provided with a nut (201) at its end, and the limiting protrusion (5) is a plate-shaped structure that extends outward along the diameter direction of the nut (201) or parallel to the diameter direction of the nut (201).

6. The limiting structure for a piezoelectric screw according to claim 5, characterized in that: The limiting protrusion (5) is fixed to the outer circumferential surface of the nut (201).

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

8. The limiting structure for a piezoelectric screw according to claim 5, characterized in that: The number of the limiting protrusions (5) is at least one. When the number of the limiting protrusions (5) is multiple, the mid-planes of the multiple limiting protrusions (5) are coplanar and the multiple limiting protrusions (5) are symmetrically distributed about the axis of the nut (201).

9. A piezoelectric screw, characterized in that: The limiting structure of the piezoelectric screw according to any one of claims 1 to 8; 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).

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