Piezoelectric actuator and moving device

Abstract

In this application, a piezoelectric actuator and a moving device are proposed. Such a piezoelectric actuator includes a housing assembly having an accommodation chamber with one end open inside, a piezoelectric assembly provided in the accommodation chamber and having a plurality of piezoelectric bodies sequentially stacked in the axial direction, and at least one protection assembly provided in the accommodation chamber and at least a part of which is provided between the inner wall of the housing assembly and the outer wall of the piezoelectric assembly. When the number of the protection assemblies is two or more, the plurality of protection assemblies are arranged so as to be spaced apart vertically. According to the piezoelectric actuator proposed in this application, the problem that the ceramics stack in the conventional piezoelectric actuator is likely to break is solved.

Description

Technical Field

[0001] This application claims the priority of the patent application with the application number 202210708090.4 and the invention title of "Piezoelectric Actuator and Moving Device", which was filed with the State Intellectual Property Office of China on June 22, 2022.

[0002] This application relates to the technical field of micro drives, and particularly to piezoelectric actuators and moving devices.

Background Art

[0003] The operating principle of a piezoelectric actuator is as follows: When a predetermined voltage is applied to a piezoelectric ceramic stack, due to the inverse piezoelectric effect of the piezoelectric material, a certain amount of strain occurs along the axial direction of the piezoelectric ceramic stack, resulting in the output of displacement.

[0004] However, due to the limitation of assembly accuracy, during the use of a piezoelectric actuator, as shown in FIG. 1, it is inevitable to receive a certain amount of tangential force F T and in the case of a low-rigidity long stack, larger radial strain is more likely to occur and cause breakage; also, as shown in FIG. 2, when the rigidity decreases, the stability of the stacked piezoelectric rod becomes weak, and due to the brittleness of the piezoelectric ceramic material and insufficient adhesive strength, the ceramic stack will directly break; moreover, as shown in FIG. 3, when the rigidity decreases, the resonance frequency of the ceramic stack also decreases, and it is even more likely for the ceramic stack to break under external excitation (such as vibration and impact during the transportation process).

[0005] In an operating state with a longer stroke, a longer piezoelectric ceramic stack is required. However, when the piezoelectric ceramic stack becomes longer, the rigidity of the entire ceramic stack decreases, and the breakage of the ceramic stack is even more likely to occur.

Summary of the Invention

[0006] In view of the drawbacks of the above-described conventional technologies, the present application aims to provide a piezoelectric actuator and a moving device for solving the problem that the ceramic stack in a conventional piezoelectric actuator is likely to break, and is advantageous for realizing an operating state where the stroke of the piezoelectric actuator is long.

[0007] To achieve the above object and other related objects, the present application provides a piezoelectric actuator, and such a piezoelectric actuator includes a housing assembly having an accommodation chamber with one end open inside, a piezoelectric assembly provided in the accommodation chamber and having a plurality of piezoelectric bodies sequentially stacked in the axial direction, at least one protection assembly provided in the accommodation chamber and at least a part of which is provided between the inner wall of the housing assembly and the outer wall of the piezoelectric assembly, When the number of the protection assemblies is two or more, the plurality of protection assemblies are arranged at intervals in the vertical direction.

[0008] Optionally, the protection assembly includes a stopper with at most one side fixed to the inner wall of the housing assembly or the outer wall of the piezoelectric assembly and the non-fixed side being in close contact with the inner wall of the housing assembly and / or the outer wall of the piezoelectric assembly, the stopper having at least one lubricating surface provided at least on the non-fixed side of the stopper.

[0009] Optionally, the stopper has its outer side fixedly connected to the inner wall of the housing assembly, its inner side in close contact with the outer wall of the piezoelectric assembly, and the lubricating surface provided at least on the inner side of the stopper.

[0010] Optionally, the stopper has its outer side in close contact with the inner wall of the housing assembly, its inner side fixedly connected to the outer wall of the piezoelectric assembly, and the lubricating surface provided at least on the outer side of the stopper.

[0011] Optionally, the stopper is in close contact with the inner wall of the housing assembly on the outside and in close contact with the outer wall of the piezoelectric assembly on the inside, and the lubricating surface is provided at least on the outside and inside of the stopper.

[0012] Optionally, when the stopper is provided at the connection location of two adjacent piezoelectric bodies, the protection assembly further includes a connecting member fixedly connected between the two adjacent piezoelectric bodies, the stopper is fixedly connected to the connecting member on the inside and is in close contact with the inner wall of the housing assembly on the outside, and at this time, the lubricating surface is provided at least on the outside of the stopper.

[0013] Optionally, a sliding groove is provided at the location on the inner wall of the housing assembly opposite to the stopper, and the stopper is provided in the sliding groove.

[0014] Optionally, the equivalent friction coefficient of the stopper satisfies the formula

Equation

[0015] Optionally, the piezoelectric actuator includes a cover plate provided in the opening, connected to the housing assembly, and having a through hole with a stepped cross-sectional shape, a pedestal connected to the piezoelectric assembly, and a through member provided on the pedestal and extending upward and penetrating through the through hole, and further includes an output assembly having the same. The cross-sectional shape of the output assembly is stepped, and a movement space is surrounded within the wide area of the through-hole by the output assembly and the cover plate.

[0016] Optionally, the piezoelectric actuator further includes an elastic assembly provided within the movement space and arranged to go around the periphery outside the through-member.

[0017] Optionally, the elastic assembly includes a disc spring and / or a spring.

[0018] Optionally, there are a first gap and a second gap between the outer wall of the through-member and the inner wall of the through-hole, the second gap is larger than the first gap, and the first gap satisfies the formula δ1 < ω max where δ1 is the first gap and ω max is the maximum deflection of the strain due to the deflection of the piezoelectric assembly.

[0019] Optionally, the piezoelectric body includes a piezoelectric ceramic chip or a piezoelectric ceramic stack, and the piezoelectric ceramic stack includes at least two piezoelectric ceramic chips stacked vertically.

[0020] The present application further proposes a moving device, and such a moving device includes the piezoelectric actuator according to any one of the above items.

[0021] As described above, in the piezoelectric actuator and the moving device according to the present application, a protection assembly is added, and one or more stoppers are added in the radial direction of the piezoelectric assembly, so that the distortion caused by the deflection of the piezoelectric assembly is reduced and its breakage is prevented; in addition, the protection assembly plays a guiding role and provides a certain degree of movement space in the axial direction, so that the telescopic movement of the piezoelectric assembly proceeds smoothly and unobstructed, and the phenomena of movement locking and stack breakage are prevented; moreover, the protection assembly is advantageous for increasing the stroke of the piezoelectric actuator by increasing the length of the piezoelectric assembly. The piezoelectric actuator according to the present application not only has high stability and high reliability, but also has a longer stroke.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Explanation of Signs

[0023] 10: Housing assembly 11: Accommodation chamber 12: Sliding groove 20: Piezoelectric assembly 21: Piezoelectric body 30: Protection assembly 31: Stopper 32: Connecting member 40: Cover plate 41: Through hole 50: Output assembly 51: Pedestal 52: Through member 60: Elastic assembly

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described using specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can be implemented or used by other different embodiments, and various modifications or changes can be made to each detail of this specification without departing from the spirit of the present application based on different viewpoints and applications.

[0025] Refer to FIGS. 4 to 10. It should be particularly noted that the illustrations proposed in this embodiment are merely for exemplarily explaining the basic concept of the present application, and the illustrations are not drawn based on the number, shape, and dimensions of the actual assembled components during implementation. Instead, they only show the assemblies related to the present application. However, the form, number, and proportion of each assembly during actual implementation can be arbitrarily changed, and moreover, the layout form of the assemblies may become more complex.

[0026] As shown in FIGS. 4 to 7, in this embodiment, a piezoelectric actuator is proposed. Such a piezoelectric actuator includes a housing assembly 10, a piezoelectric assembly 20, and at least one protection assembly 30. Further, such a piezoelectric actuator further includes a cover plate 40 and an output assembly 50. Even further, such a piezoelectric actuator further includes an elastic assembly 60.

[0027] The housing assembly 10 has a receiving chamber 11 with one end open inside. The receiving chamber 11 is for mounting and fixing the piezoelectric assembly 20. A cover plate 40 is mounted and fixed at the opening of the receiving chamber 11. Also, the opening of the receiving chamber 11 is a joint for mounting and positioning the piezoelectric actuator externally and a joint for displacement output. In actual application, the housing assembly 10 is usually a metal processed product or a ceramic processed product, and functions to protect the piezoelectric assembly 20 inside it.

[0028] The piezoelectric assembly 20 is provided in the receiving chamber 11 and has a plurality of piezoelectric bodies 21 laminated sequentially in the axial direction.

[0029] Specifically, the piezoelectric assembly 20 is a displacement generating structure, one end of which is fixed to the bottom end away from the opening of the receiving chamber 11, and the other end is fixedly connected to the output assembly 50. When a predetermined voltage is applied to the piezoelectric assembly 20, due to the inverse piezoelectric effect of the piezoelectric material, a certain amount of strain occurs along the axial direction of the piezoelectric assembly 20, and this strain is transmitted to the output assembly 50 to become the output of displacement.

[0030] More specifically, the piezoelectric body 21 includes a piezoelectric ceramic chip or a piezoelectric ceramic stack, and the piezoelectric ceramic stack includes at least two piezoelectric ceramic chips stacked one above the other. In other words, the piezoelectric assembly 20 is composed of at least two piezoelectric ceramic chips sequentially stacked in the axial direction; with such a stacking design, the length of the entire piezoelectric assembly 20 in the axial direction can be increased, and furthermore, the displacement output force of the piezoelectric actuator can be increased.

[0031] The protection assembly 30 is provided in the accommodation chamber 11, and at least a part of it is provided between the inner wall of the housing assembly 10 and the outer wall of the piezoelectric assembly 20; when the number of the protection assemblies 30 is two or more, the plurality of protection assemblies 30 are arranged at intervals one above the other.

[0032] Specifically, the protection assembly 30 includes a stopper 31 with at most one side fixed to the inner wall of the housing assembly 10 or the outer wall of the piezoelectric assembly 20, and the non-fixed side being in close contact with the inner wall of the housing assembly 10 and / or the outer wall of the piezoelectric assembly 20. The stopper 31 has at least one lubricating surface, and the lubricating surface is provided at least on the non-fixed side of the stopper 31. In other words, at least one non-fixed side of the stopper 31 is provided with a lubricating surface.

[0033] More specifically, in order to ensure the stable operation of the piezoelectric actuator, the equivalent friction coefficient of the stopper 31 satisfies the formula

Number

[0034] Specifically, when the stopper 31 is fixed to the inner wall of the housing assembly 10, that is, when the outer side of the stopper 31 is the fixed side and the inner side is the non-fixed side, the equivalent friction coefficient of the stopper 31 is the friction coefficient between the stopper 31 and the outer wall of the piezoelectric assembly 20; when the stopper 31 is fixed to the outer wall of the piezoelectric assembly 20, that is, when the outer side of the stopper 31 is the non-fixed side and the inner side is the fixed side, the equivalent friction coefficient of the stopper 31 is the friction coefficient between the stopper 31 and the inner wall of the housing assembly 10; when the stopper 31 is not fixed to the inner wall of the housing assembly 10 nor to the outer wall of the piezoelectric assembly 20, that is, when both the outer side and the inner side of the stopper 31 are non-fixed sides, the equivalent friction coefficient of the stopper 31 is the total friction coefficient existing between the stopper 31 and the inner wall of the housing assembly 10 and between the stopper 31 and the outer wall of the piezoelectric assembly 20.

[0035] In actual applications, as long as the stopper 31 is made of a self-lubricating material (such as polytetrafluoroethylene, polyetheretherketone, etc.), the frictional force between the stopper 31 and the housing assembly 10 and / or between the stopper 31 and the piezoelectric assembly 20 will be reduced, and it will play a guiding role for the piezoelectric assembly 20. Therefore, the telescopic movement of the piezoelectric assembly 20 proceeds smoothly and unobstructed, and the phenomena of movement locking and stack breakage are prevented; in addition, the self-lubricating material has a certain degree of elasticity and plays a buffering role for the displacement and vibration in the radial direction of the piezoelectric assembly 20, so it can be prevented from breaking after being subjected to vibration or impact.

[0036] In actual applications, the shapes of the cross-sections of the accommodation chamber 11 and the piezoelectric assembly 20 are usually circular, and the stopper 31 is an annular workpiece made of a self-lubricating material; of course, the stopper 31 may also be a plurality of rectangular workpieces made of a self-lubricating material, etc., which will not affect this embodiment.

[0037] In the first exemplary embodiment, the stopper 31 is in close contact with the inner wall of the housing assembly 10 on the outside and in close contact with the outer wall of the piezoelectric assembly 20 on the inside, and lubricating surfaces are provided at least on the outside and the inside of the stopper 31. In this exemplary embodiment, the stopper 31 is provided in an interference fit form between the inner wall of the housing assembly 10 and the outer wall of the piezoelectric assembly 20, and both its inside and outside are non-fixed sides; by making its inner surface and outer surface into lubricating surfaces, the frictional force between the piezoelectric assembly 20 and the stopper 31 during movement, and between the stopper 31 and the housing assembly 10 is reduced, and since the frictional force is large during the movement of the piezoelectric assembly 20, a large stress is generated on the stopper 31, preventing the piezoelectric assembly 20 from breaking. In addition, the stopper 31 can play a guiding role for the movement of the piezoelectric assembly 20.

[0038] In the second exemplary embodiment, the stopper 31 is fixedly connected to the inner wall of the housing assembly 10 on the outside and in close contact with the outer wall of the piezoelectric assembly 20 on the inside, and a lubricating surface is provided at least on the inside of the stopper 31. In this exemplary embodiment, the stopper 31 has a fixed side on the outside and a non-fixed side on the inside; by making its inner surface into a lubricating surface, the frictional force between the piezoelectric assembly 20 and the stopper 31 during movement is reduced, and since the frictional force is large during the movement of the piezoelectric assembly 20, a large stress is generated on the stopper 31, preventing the piezoelectric assembly 20 from breaking. In addition, the stopper 31 can play a guiding role for the movement of the piezoelectric assembly 20.

[0039] In the third illustration, the stopper 31 has its outer side in close contact with the inner wall of the housing assembly 10 and its inner side fixedly connected to the outer wall of the piezoelectric assembly 20, and at least the outer side of the stopper 31 is provided with a lubricating surface. In this illustration, the stopper 31 has its inner side as the fixed side and its outer side as the non-fixed side; by making the outer surface thereof a lubricating surface, the frictional force between the moving stopper 31 and the housing assembly 10 is reduced, and since the frictional force is large during the movement of the piezoelectric assembly 20, a large stress is generated in the stopper 31, preventing the piezoelectric assembly 20 from breaking. In addition, the stopper 31 can play a guiding role in the movement of the piezoelectric assembly 20.

[0040] As shown in FIG. 6, in the fourth illustration, when the stopper 31 is provided at the connection portion between two adjacent piezoelectric bodies 21, the protection assembly 30 further includes a connecting member 32 fixedly connected between the two adjacent piezoelectric bodies 21. The stopper 31 has its inner side fixedly connected to the connecting member 32 and its outer side in close contact with the inner wall of the housing assembly 10. At this time, at least the outer side of the stopper 31 is provided with a lubricating surface. In this illustration, the stopper 31 has its inner side as the fixed side and its outer side as the non-fixed side; by making the outer surface thereof a lubricating surface, the frictional force between the moving stopper 31 and the housing assembly 10 is reduced, and since the frictional force is large during the movement of the piezoelectric assembly 20, a large stress is generated in the stopper 31, preventing the piezoelectric assembly 20 from breaking. In addition, the stopper 31 can play a guiding role in the movement of the piezoelectric assembly 20.

[0041] It should be particularly noted that, compared with the protection assembly 30 according to the fourth illustration, the protection assemblies 30 according to the first to third illustrations only include the stopper 31, so they are characterized by having a simple structure, low cost, low load capacity, and being suitable for piezoelectric actuators with a medium displacement stroke; on the other hand, the protection assembly 30 according to the fourth illustration includes, in addition to the stopper 31, a connecting member 32, and it is because of the design of the connecting member 32 that it becomes suitable for piezoelectric actuators with a longer displacement stroke.

[0042] In the above example, when the outside of the stopper 31 is the non-fixed side, a sliding groove 12 is provided at the position on the inner wall of the housing assembly 10 facing the stopper 31, and the stopper 31 is provided in the sliding groove 12, whereby the movement of the stopper 31 is restricted.

[0043] As shown in FIG. 7, the cover plate 40 is provided at the opening of the accommodation chamber 11, connected to the housing assembly 10, and has a through-hole 41 whose cross-sectional shape is stepped. In actual application, the cover plate 40 can be manufactured together with the housing assembly 10 and thus integrally formed.

[0044] The output assembly 50 includes a pedestal 51 connected to the piezoelectric assembly 20 and a through-member 52 provided on the pedestal 51 and extending upward to penetrate through the through-hole 41; the cross-sectional shape of the output assembly 50 is stepped, and the output assembly 50 and the cover plate 40 enclose a movement space within the wide area of the through-hole 41.

[0045] Specifically, the output assembly 50 is a rigid structure and is directly fixedly connected to the piezoelectric assembly 20 for directly outputting the position of the piezoelectric assembly 20 to the outer end of the piezoelectric actuator.

[0046] Specifically, there are a first gap δ1 and a second gap δ2 between the outer wall of the through-member 52 and the inner wall of the through-hole 41, the second gap δ2 is larger than the first gap δ1, and the first gap δ1 satisfies the formula δ1 < ω max wherein, ω max is the maximum deflection of the strain due to the deflection of the piezoelectric assembly.

[0047] As shown in FIG. 7, the elastic assembly 60 is provided within the above-described movement space and is provided to surround the outside of the through member 52. Specifically, the elastic assembly 60 is located between the cover plate 40 and the pedestal 51, and the elastic force after distortion due to its compression reacts on the piezoelectric assembly 20, applying a preload to the piezoelectric assembly 20 to accelerate the contraction of the piezoelectric assembly 20. In actual applications, the elastic assembly 60 includes a disc spring and / or a spring.

[0048] As described in the foregoing (Background Art), due to the causes of breakage of the long stack, the breakage is classified into three types: (1) breakage due to receiving an eccentric force, (2) breakage due to instability of the piezoelectric rod, and (3) breakage due to vibration; hereinafter, the performance of the piezoelectric actuator according to this embodiment will be briefly analyzed based on the three types of breakage; here, as the protection assembly 30 of the piezoelectric actuator according to this embodiment, the structure shown in the fourth exemplification is used.

[0049] (1) Breakage due to receiving an eccentric force In the structure of the piezoelectric actuator according to this embodiment, the operating state of receiving an eccentric force is actually a state in which an axial force and a tangential force are combined, and hereinafter, the two types of force-receiving situations will be decomposed and described.

[0050] When receiving a tangential force, the piezoelectric assembly 20 can be simplified to a cantilever structure with one end fixed, as shown in FIG. 8, where F T is the tangential force received by the cantilever structure; the strain due to the deflection of the cantilever satisfies the formula

Equation

[0051] As can be seen from the above, when the length of the piezoelectric assembly 20 in the axial direction increases, the overall rigidity

Number

[0052] When receiving an axial force, as described above, if the first gap between the cover plate 40 and the output assembly 50 is controlled within a fairly small range, the piezoelectric assembly 20 can be simplified to an elongated rod structure with both ends fixed, as shown in Fig. 9. The Euler formula for the critical pressure of the piezoelectric rod is

Number

Number

[0053] As can be understood from the above, when the length of the piezoelectric assembly 20 increases, the critical pressure of the piezoelectric rod decreases significantly. Therefore, in a pressure-receiving state, breakage is more likely to occur. In the case of a piezoelectric assembly with a given material and cross-section, to increase the critical pressure of the piezoelectric rod and prevent breakage under pressure, the only way is to increase the positioning points and divide the slender rod into a combination of multi-stage short rods.

[0054] In other words, the piezoelectric assembly 20 is divided into a plurality of thick and short piezoelectric rods by the connecting member 32. At this time, the piezoelectric assembly 20 is equivalently converted into a plurality of slender rods fixed at both ends. For example, the piezoelectric assembly 20 is divided into (n + 1) slender rods by n connecting members 32, and the critical pressure of the piezoelectric rod satisfies the formula

Equation

[0055] (2) Breakage due to instability of the piezoelectric rod The breakage due to the instability of the piezoelectric rod is the same as the breakage due to the axial force described above, and will not be described repeatedly here.

[0056] (3) Breakage due to vibration As described above, when the first gap between the cover plate 40 and the output assembly 50 is controlled within a fairly small range, the piezoelectric assembly 20 can be simplified into a vibration system model with a simply supported beam as shown in FIG. 10. When analyzing the characteristics of the free vibration of the piezoelectric assembly by the static strain method, the formula

Equation

Number

Number

[0057] As can be seen from the above, in the case of a piezoelectric assembly with a given material and cross-section, in order to increase the natural frequency of the entire system and prevent the piezoelectric actuator from being affected by external shocks and vibrations and causing resonance and breakage, by increasing the positioning points, the slender rod can also be divided into a combination of multi-stage short rods.

[0058] In other words, the piezoelectric assembly 20 is divided into a plurality of thick and short piezoelectric rods by the connecting member 32. For example, the piezoelectric assembly 20 is divided into (n + 1) piezoelectric rods by n connecting members 32. At this time, the natural frequency of the piezoelectric assembly 20 is

Number

[0059] Correspondingly, in this embodiment, a moving device including the above-described piezoelectric actuator is proposed. Here, the moving device may be any one of the conventional devices to which the piezoelectric actuator is applied, and this is not limited in this embodiment.

[0060] To summarize the above, in the piezoelectric actuator and the moving device according to the present application, a protection assembly is added, and one or more stoppers are increased in the radial direction of the piezoelectric assembly, so that the distortion caused by the deflection of the piezoelectric assembly is reduced and its breakage is prevented; in addition, the protection assembly serves as a guiding function and provides a certain degree of movement space in the axial direction, so that the telescopic movement of the piezoelectric assembly proceeds smoothly and without obstruction, and the phenomena of movement locking and stack breakage are prevented; moreover, the protection assembly is advantageous for increasing the stroke of the piezoelectric actuator by increasing the length of the piezoelectric assembly. The piezoelectric actuator according to the present application not only has high stability and high reliability, but also has a longer stroke. Therefore, the present application effectively overcomes various drawbacks in the prior art and has a high industrial utilization value.

[0061] The above-described embodiments are merely illustrative of the principles and effects of the present application and do not limit the present application. Any person familiar with this technology can make modifications and changes to the above-described embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those having ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present application shall be covered by the claims of the present application.

Claims

1. A housing assembly (10) having an accommodation chamber (11) with one end open therein, A piezoelectric assembly (20) provided in the accommodation chamber (11), having one end fixed to the bottom away from the opening of the accommodation chamber (11), and having a plurality of piezoelectric bodies (21) stacked sequentially in the axial direction, At least one protection assembly (30) provided in the accommodation chamber (11), with at least a part thereof provided between the inner wall of the housing assembly (10) and the outer wall of the piezoelectric assembly (20), When the number of the protection assemblies (30) is two or more, the plurality of protection assemblies (30) are arranged at intervals vertically, The protection assembly (30) includes a stopper (31) with at most one side fixed to the inner wall of the housing assembly (10) or the outer wall of the piezoelectric assembly (20), and the non-fixed side being in close contact with the inner wall of the housing assembly (10) and / or the outer wall of the piezoelectric assembly (20). The stopper (31) has at least one lubricating surface, and the lubricating surface is provided at least on the non-fixed side of the stopper (31), The equivalent friction coefficient of the stopper (31) is given by the formula 【Number 1】 satisfies the formula, where k is the rigidity of the stopper (31), D is the thickness of the stopper (31), δ is the distance between the inner wall of the housing assembly (10) and the outer wall of the piezoelectric assembly (20), μ is the equivalent friction coefficient of the stopper (31), E is the Young's modulus of the stopper (31), A is the cross-sectional area of the piezoelectric assembly (20), A ｉ is the effective pressing area of the piezoelectric assembly (20) against the stopper (31), σ is the tensile strength of the piezoelectric assembly (20), σ ａｄ is the tensile adhesion strength of the piezoelectric assembly (20), σ ｃｅ is the tensile strength of the piezoelectric ceramic chip in the piezoelectric assembly (20). A piezoelectric actuator characterized by the above.

2. The stopper (31) has its outer side fixedly connected to the inner wall of the housing assembly (10) and its inner side in close contact with the outer wall of the piezoelectric assembly (20), The piezoelectric actuator according to claim 1, characterized in that the lubricating surface is provided at least on the inner side of the stopper (31).

3. The stopper (31) has its outer side in close contact with the inner wall of the housing assembly (10) and its inner side fixedly connected to the outer wall of the piezoelectric assembly (20), The piezoelectric actuator according to claim 1, characterized in that the lubricating surface is provided at least on the outer side of the stopper (31).

4. The stopper (31) has its outer side in close contact with the inner wall of the housing assembly (10) and its inner side in close contact with the outer wall of the piezoelectric assembly (20), The piezoelectric actuator according to claim 1, characterized in that the lubricating surface is provided at least on the outer side and the inner side of the stopper (31).

5. When the stopper (31) is provided at the connection portion of two adjacent piezoelectric bodies (21), the protection assembly (30) further includes a connecting member (32) fixedly connected between two adjacent piezoelectric bodies (21). The stopper (31) is fixedly connected to the connecting member (32) on the inner side and is in close contact with the inner wall of the housing assembly (10) on the outer side. At this time, the lubricating surface is provided at least on the outer side of the stopper (31). The piezoelectric actuator according to claim 1, characterized in that.

6. A sliding groove (12) is provided at a position on the inner wall of the housing assembly (10) facing the stopper (31), and the stopper (31) is provided in the sliding groove (12). The piezoelectric actuator according to any one of claims 3 to 5, characterized in that.

7. The piezoelectric actuator is A cover plate (40) provided in the opening, connected to the housing assembly (10), and having a through hole (41) with a stepped cross-sectional shape. An output assembly (50) having a pedestal (51) connected to the piezoelectric assembly (20), and a through member (52) provided on the pedestal (51) and extending upward and penetrating through the through hole (41). The cross-sectional shape of the output assembly (50) is stepped, and a movement space is surrounded within a wide area of the through hole (41) by the output assembly (50) and the cover plate (40). The piezoelectric actuator according to claim 1, characterized in that.

8. The piezoelectric actuator further includes an elastic assembly (60) provided in the movement space and provided to surround the outside of the through member (52). The piezoelectric actuator according to claim 7, characterized in that.

9. The elastic assembly (60) includes a disc spring and / or a spring. The piezoelectric actuator according to claim 8, characterized in that.

10. There are a first gap and a second gap between the outer wall of the through member (52) and the inner wall of the through hole (41), the second gap is larger than the first gap, and the first gap satisfies the formula δ1 < ω ｍａｘ wherein δ1 is the first gap and ω ｍａｘ is the maximum deflection of the strain due to the deflection of the piezoelectric assembly (20). The piezoelectric actuator according to claim 7, characterized in that.

11. The piezoelectric body (21) includes a piezoelectric ceramic chip or a piezoelectric ceramic stack. The piezoelectric ceramic stack includes at least two piezoelectric ceramic chips stacked vertically. The piezoelectric actuator according to claim 1, characterized in that.

12. A moving device comprising the piezoelectric actuator according to any one of claims 1 to 11.

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