Piezoelectric actuator and encapsulation method

Abstract

The present application belongs to the technical field of micro-drives. Provided is a piezoelectric actuator, comprising a housing structure, a piezoelectric structure, a protective layer, a filling encapsulation layer and a transmission output structure, wherein an accommodating space with a first opening is provided in the housing structure; the piezoelectric structure is connected to the bottom of the accommodating space; the transmission output structure is located at the first opening to output the displacement generated by the piezoelectric structure; the protective layer is located between the housing structure and the piezoelectric structure; and the filling encapsulation layer is located between the protective layer and the housing structure, and can support a stroke surface of the piezoelectric structure and prevent the piezoelectric structure from being damaged. The protective layer comprises an anti-sticking layer and an elastic encapsulation layer, which can reduce the resistance of the piezoelectric structure during an action and avoid hard contact between the piezoelectric structure and the filling encapsulation layer, thereby further improving a protection effect on the piezoelectric structure, and thus improving the structural stability and working reliability of a product. In addition, further provided in the present application is an encapsulation method for performing encapsulation to form the piezoelectric actuator.

Description

A piezoelectric actuator and its packaging method

[0001] This application claims priority to Chinese Patent Application No. 202411507007.2, filed on October 28, 2024, entitled "A piezoelectric actuator and packaging method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of micro-drive technology, and in particular to a piezoelectric actuator and its packaging method. Background Technology

[0003] A piezoelectric actuator is a device that utilizes the inverse piezoelectric effect of piezoelectric materials to achieve precise displacement control. Piezoelectric materials, such as piezoelectric ceramics, possess unique physical properties: when a voltage is applied, the piezoelectric material deforms and produces displacement; when mechanical stress is applied, the piezoelectric material generates an electric charge. Piezoelectric actuators are typically formed by stacking multiple layers of piezoelectric materials, creating a piezoelectric stack structure. Electrodes are usually connected to both ends of the piezoelectric stack. When a certain voltage is applied to the piezoelectric stack, according to the inverse piezoelectric effect, the piezoelectric stack deforms along its stacking axis, allowing the entire piezoelectric stack to provide a large displacement output. This displacement is precisely controllable, characterized by high accuracy and fast response, making it suitable for various applications requiring high-precision positioning.

[0004] Currently, prestressed piezoelectric actuators on the market consist of a piezoelectric ceramic stack, a base, an output pusher, and a housing. The base and output pusher are connected to opposite ends of the piezoelectric ceramic stack along their axial directions, and the housing is fitted around the outer periphery of the piezoelectric ceramic stack, output pusher, and base. Due to limitations in assembly precision, piezoelectric actuators are inevitably subjected to tangential impacts during use, causing the piezoelectric ceramic stack to bear significant tangential stress, which can easily lead to stack fracture and product damage. Furthermore, longer stroke applications require longer piezoelectric ceramic stacks, further increasing the risk of stack fracture.

[0005] In order to solve the above problems, this application provides a piezoelectric actuator and packaging method to reduce or prevent the risk of breakage of piezoelectric ceramic stacks. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a piezoelectric actuator and packaging method to solve the problems of easy breakage damage caused by tangential force and / or tangential impact in the prior art.

[0007] To achieve the above and other related objectives, this application provides a piezoelectric actuator, comprising:

[0008] The outer shell structure has an internal receiving space, and one end of the receiving space has a first opening;

[0009] A piezoelectric structure, located within the receiving space, has a top surface and a bottom surface opposite to each other, and a side surface connecting the top surface and the bottom surface. The bottom surface of the piezoelectric structure is connected to the bottom of the receiving space away from the first opening. The piezoelectric structure includes a plurality of piezoelectric elements, which are stacked sequentially from the bottom of the receiving space toward the direction closer to the first opening. The stacking direction of the plurality of piezoelectric elements is taken as the first direction.

[0010] A protective layer, located between the housing structure and the piezoelectric structure, includes an anti-adhesion layer that at least covers a portion of the side surface of the piezoelectric structure.

[0011] A filling encapsulation layer is located between the protective layer and the housing structure, at least partially covering the protective layer, and is spaced apart from the piezoelectric structure;

[0012] The transmission output structure is located on the side of the piezoelectric structure near the first opening, and is used to output the displacement generated by the piezoelectric structure along the first direction.

[0013] Optionally, the protective layer further includes an elastic encapsulation layer located between the anti-stick layer and the piezoelectric structure, and spaced apart from the filler encapsulation layer, wherein the elastic encapsulation layer at least covers a portion of the side surface of the piezoelectric structure.

[0014] Optionally, the filling encapsulation layer includes multiple filling segments, which are arranged sequentially at intervals along the first direction.

[0015] Optionally, the housing structure includes a housing and a base, the bottom surface of the piezoelectric structure is connected to the base, the first opening is located at one end of the housing, and the end of the housing away from the first opening is connected to the base, so that the housing is fitted around the base and the outer periphery of the piezoelectric structure, and the housing and the piezoelectric structure are spaced apart.

[0016] Optionally, when viewed from above along the first direction, the piezoelectric actuator has an annular or rectangular annular profile, and the piezoelectric structure has a circular or rectangular profile.

[0017] Optionally, the transmission output structure includes a transmission base and a transmission output member, the transmission output member being connected to the surface of the transmission base away from the piezoelectric structure; wherein, when the piezoelectric actuator is viewed from above along the first direction, the outer contour line of the transmission output member is located within the outer contour line of the transmission base.

[0018] Optionally, the piezoelectric actuator further includes:

[0019] A cover plate is provided at intervals along the first direction on the side of the transmission base away from the piezoelectric structure and is fixedly connected to the housing structure. The cover plate has a through hole that extends along the first direction, and the transmission output member passes through the through hole.

[0020] An elastic element surrounds the outside of the transmission output element and is located between the cover plate and the transmission base.

[0021] Optionally, the piezoelectric actuator further includes an isolation pad located between the transmission output structure and the piezoelectric structure, connected to the piezoelectric structure, and in sliding contact with the transmission output structure.

[0022] Optionally, the housing structure is a metal workpiece or a ceramic workpiece to protect the piezoelectric structure; or, the piezoelectric element is a piezoelectric ceramic monolith; or, the material of the filling encapsulation layer is a high-rigidity encapsulating adhesive or a composite material; or, the transmission output structure is spaced apart from the sidewall of the first opening.

[0023] Optionally, the anti-stick layer is an oil-based coating or a nano-coating; and / or, the elastic encapsulation layer is made of an elastic material.

[0024] Optionally, the housing structure is an integral structure or a discrete structure; and / or, the transmission output structure is an integral structure or a discrete structure.

[0025] Optionally, the packaging shell can be bonded to the packaging base, or fixedly connected to the packaging base by threads, or fixedly fixed to the packaging base by welding.

[0026] This application also provides a packaging method for a piezoelectric actuator, used to package and form any of the piezoelectric actuators described in the foregoing embodiments, comprising the following steps:

[0027] A piezoelectric structure, a housing structure, and a transmission output structure are provided. The housing structure has a receiving space, and one end of the receiving space has a first opening.

[0028] A protective layer is formed on the side of the piezoelectric structure;

[0029] The piezoelectric structure is fixedly connected to the bottom of the accommodating space;

[0030] A filling and encapsulation layer is formed between the protective layer and the outer shell structure;

[0031] The transmission output structure is installed at the first opening of the housing structure to output the displacement generated by the piezoelectric structure along the first direction.

[0032] Optionally, the protective layer includes an anti-stick layer and an elastic encapsulation layer, and forming the protective layer on the side of the piezoelectric structure includes the following steps:

[0033] An elastic encapsulation layer is formed on the side of the piezoelectric structure;

[0034] The anti-stick layer is formed on the surface of the elastic encapsulation layer, and the anti-stick layer completely covers the elastic encapsulation layer.

[0035] Optionally, the housing structure includes an encapsulation housing and an encapsulation base, and fixing the piezoelectric structure to the bottom of the receiving space includes the following steps:

[0036] The piezoelectric structure is fixedly connected to the packaging base;

[0037] The encapsulation shell is fitted onto the outer periphery of the piezoelectric structure and fixedly connected to the encapsulation base.

[0038] Optionally, the transmission output structure includes a transmission base and a transmission output component, and the piezoelectric actuator further includes a cover plate and an elastic element. After installing the transmission output structure into the first opening of the housing structure, the following steps are further included:

[0039] The elastic element is sleeved on the outer periphery of the transmission output element;

[0040] The cover plate is fitted onto the outer periphery of the transmission output component, and the elastic member is pressed down toward the transmission base so that the elastic member abuts against the transmission base.

[0041] The cover plate is fixedly connected to the outer shell structure.

[0042] Optionally, the step of forming the anti-stick layer on the surface of the resilient encapsulation layer includes:

[0043] An anti-stick material is applied to the side surface of the piezoelectric structure to form the anti-stick layer, or the anti-stick material is applied to a portion of the side surface of the piezoelectric structure to form the anti-stick layer, wherein the anti-stick material is an oil-based material or a nanomaterial, and the thickness of the anti-stick layer is less than 50 μm; and / or,

[0044] The step of forming an elastic encapsulation layer on the side of the piezoelectric structure includes:

[0045] An elastic material is coated onto the surface of the piezoelectric structure to form the elastic encapsulation layer, such that the elastic encapsulation layer covers at least a portion of the surface of the piezoelectric structure.

[0046] The elastic material is polyurethane, rubber, or graphite, and the thickness of the elastic encapsulation layer is 10 μm to 1 μm.

[0047] Optionally, the step of fixing the piezoelectric structure to the bottom of the receiving space includes:

[0048] The bottom surface of the piezoelectric structure is fixedly connected to the bottom of the receiving space by bonding, or an adhesive material is applied to the bottom of the receiving space and the piezoelectric structure is placed on the adhesive material so that the piezoelectric structure is fixedly connected to the bottom of the receiving space, wherein the piezoelectric structure is connected to the central region of the bottom of the receiving space.

[0049] Optionally, the step of fitting the encapsulation housing onto the outer periphery of the piezoelectric structure and fixing it to the encapsulation base includes:

[0050] The outer casing and the base are fixedly connected by adhesive bonding, or by welding, or by threaded connection.

[0051] Optionally, the piezoelectric actuator further includes an isolation pad, and the step of mounting the transmission output structure to the first opening of the housing structure includes:

[0052] An adhesive material is applied to the top surface of the piezoelectric structure;

[0053] The insulating pad is installed on the top surface of the piezoelectric structure to fix the insulating pad to the piezoelectric structure.

[0054] As described above, the piezoelectric actuator and packaging method provided in this application have at least the following beneficial effects:

[0055] The piezoelectric actuator of this application includes a protective layer and a filler encapsulation layer. The filler encapsulation layer supports the stroke surface of the piezoelectric structure, effectively dispersing impact energy and preventing damage to the piezoelectric structure due to excessive local stress. The anti-stick layer of the protective layer prevents adhesion between the filler encapsulation layer and the piezoelectric structure, helping to reduce the motion resistance of the piezoelectric structure and ensuring the displacement output of the piezoelectric actuator. Furthermore, the protective layer includes an elastic encapsulation layer to prevent hard contact between the piezoelectric structure and the filler encapsulation layer, reducing the constraint of the piezoelectric structure in the displacement direction and further ensuring the stable output of the piezoelectric actuator. Therefore, the piezoelectric actuator of this application can apply elastic constraint to the piezoelectric structure when subjected to tangential impact, effectively reducing or avoiding the risk of damage to the piezoelectric structure. At the same time, while ensuring the protection of the piezoelectric structure, it effectively reduces the resistance during the operation of the piezoelectric actuator, improves the structural stability and operational reliability of the product, and thus improves the applicability of the piezoelectric actuator, enabling it to adapt to various complex application scenarios. It effectively overcomes various defects in the prior art and has high industrial application value. Attached Figure Description

[0056] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 shows a schematic diagram of the structure of the piezoelectric actuator provided in Embodiment 1 of this application.

[0058] Figure 2 shows a schematic diagram of the specific structure of the piezoelectric actuator housing provided in Embodiment 1 of this application.

[0059] Figure 3 shows a schematic diagram of the side of the piezoelectric structure covered by the protective layer provided in Embodiment 1 of this application.

[0060] Figure 4 shows a schematic diagram of the structure of a piezoelectric actuator in the prior art.

[0061] Figure 5 shows a schematic diagram of the structure of a piezoelectric actuator with an elastic encapsulation layer provided in Embodiment 1 of this application.

[0062] Figures 6 to 9 show schematic diagrams of four cross-sections of the piezoelectric actuator provided in Embodiment 1 of this application, perpendicular to the first direction.

[0063] Figures 10 and 11 show schematic diagrams of the piezoelectric actuators with two and three filling segments respectively, provided in Embodiment 1 of this application.

[0064] Figure 12 shows a schematic diagram of the structure of a piezoelectric actuator with an isolation pad provided in Embodiment 1 of this application.

[0065] Figure 13 shows a schematic flowchart of the packaging method for the piezoelectric actuator provided in Embodiment 2 of this application.

[0066] Figure 14 shows a schematic diagram of a protective layer formed on the side of a piezoelectric structure according to Embodiment 2 of this application.

[0067] Figure 15 shows a schematic diagram of the structure for forming a filling encapsulation layer provided in Embodiment 2 of this application.

[0068] Figure 16 shows a schematic diagram of the structure of fixing the piezoelectric structure to the packaging base according to Embodiment 2 of this application.

[0069] Schematic diagram of reference numerals: 1. Outer shell structure; 11. Encapsulation shell; 12. Encapsulation base; 101. Accommodation space; 102. First opening; 2. Piezoelectric structure; 21. Piezoelectric element; 3. Protective layer; 31. Anti-stick layer; 32. Elastic encapsulation layer; 4. Filling encapsulation layer; 41. Filling segment; 5. Transmission output structure; 51. Transmission output component; 52. Transmission base; 61. Cover plate; 611. Through hole; 62. Elastic element; 7. Isolation gasket; 81. Piezoelectric ceramic stack; 82. Shell base; 83. Output pusher; 83. Outer shell. Detailed Implementation

[0070] To make the technical objectives, technical solutions, and technical effects of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0071] Therefore, the following detailed description of embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] In the description of this application, it should be noted that the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with an implementation or example, which are included in at least one implementation or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same implementation or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more implementations or examples.

[0073] Example 1

[0074] This embodiment provides a piezoelectric actuator to solve the problem that piezoelectric stacks are easily damaged when piezoelectric actuators are subjected to tangential stress in the prior art. Referring to FIG1, the piezoelectric actuator provided in this embodiment includes a housing structure 1, a piezoelectric structure 2, a protective layer 3, a filling and encapsulation layer 4, and a transmission output structure 5.

[0075] Referring to Figures 1 and 2, the housing structure 1 has a receiving space 101, and one end of the receiving space 101 has a first opening 102. The receiving space 101 is used to install and fix the piezoelectric structure 2. The transmission output structure 5 at the first opening 102 is the external mounting and positioning structure and displacement output structure of the piezoelectric actuator. In practical applications, the housing structure 1 is generally a metal or ceramic workpiece, which serves to protect the internal piezoelectric structure 2. Specifically, the material of the housing structure 1 can be stainless steel, copper alloy, titanium alloy, or other suitable materials.

[0076] A piezoelectric structure 2 is disposed within the receiving space 101. The piezoelectric structure 2 is a displacement generating structure, having a top surface and a bottom surface opposite to each other, and a side surface connecting the top and bottom surfaces. The bottom surface of the piezoelectric structure 2 is connected to the bottom of the receiving space 101 away from the first opening 102. The piezoelectric structure 2 includes multiple piezoelectric elements 21, which are stacked sequentially from the bottom of the receiving space 101 towards the direction closer to the first opening 102. The stacking direction of the multiple piezoelectric elements 21 is defined as the first direction. In practical applications, when a certain voltage is applied to the piezoelectric structure 2, due to the inverse piezoelectric effect of the piezoelectric material, the piezoelectric structure 2 undergoes a certain deformation along the first direction. This deformation is transmitted to the transmission output structure 5, forming a displacement output.

[0077] In an optional embodiment, the piezoelectric element 21 is a piezoelectric ceramic monolith. Multiple piezoelectric ceramic monoliths are stacked sequentially from the bottom of the receiving space 101 to form a piezoelectric ceramic stack, which effectively increases the length of the piezoelectric structure 2 along the first direction, thereby improving the displacement output of the piezoelectric actuator.

[0078] Referring to Figures 1 and 3, the protective layer 3 is disposed between the housing structure 1 and the piezoelectric structure 2 to protect the piezoelectric structure 2, prevent damage to the piezoelectric structure 2 when the piezoelectric actuator is subjected to tangential impact, and reduce the constraint on the displacement of the piezoelectric structure 2 along the first direction. The protective layer 3 includes an anti-adhesion layer 31, which covers at least part of the side surface of the piezoelectric structure 2 to reduce the resistance when the piezoelectric structure 2 is activated. Optionally, the anti-adhesion layer 31 may cover part of the side surface of the piezoelectric structure 2 or cover the entire side surface of the piezoelectric structure 2. For example, the anti-adhesion layer 31 covers the area of ​​the side surface of the piezoelectric structure 2 except for the area near the first opening 102 and the bottom of the receiving space 101.

[0079] A filler encapsulation layer 4 is formed between the protective layer 3 and the outer shell structure 1, at least partially covering the protective layer 3, and spaced apart from the piezoelectric structure 2. The filler encapsulation layer 4 can support the stroke surface (side) of the piezoelectric structure 2, fully decompose the impact energy generated by tangential stress, and prevent excessive local stress from damaging the piezoelectric structure 2. It can also cooperate with the protective layer 3 to ensure the stable output of the piezoelectric actuator. Optionally, the material of the filler encapsulation layer 4 can be a high-rigidity encapsulating adhesive, composite material, or other suitable material. Further, the material of the filler encapsulation layer 4 is, for example, an encapsulating epoxy.

[0080] It should be noted that, in order to ensure the motion output of the piezoelectric structure 2, the portion of the side of the piezoelectric structure 2 covered by the anti-stick layer 31 should be greater than or equal to the contact surface between the filling encapsulation layer 4 and the piezoelectric structure 2.

[0081] The transmission output structure 5 is located on the side of the piezoelectric structure 2 near the first opening 102, passes through the first opening 102 and extends to the outside of the receiving space 101, and is used to output the displacement generated by the piezoelectric structure 2 along the first direction. Optionally, the transmission output structure 5 is spaced apart from the side wall of the first opening 102.

[0082] In the prior art, referring to Figure 4, the structure of the prestressed piezoelectric actuator consists of a piezoelectric ceramic stack 81, a housing base 82, an output pusher 83, and a housing 83. A space is reserved between the piezoelectric ceramic stack 81 and the housing 83 to facilitate installation and prevent interference with the actuation effect. When the piezoelectric actuator is subjected to a tangential impact perpendicular to the first direction, the tangential force is transmitted to the piezoelectric ceramic stack 81. Due to the brittleness of the piezoelectric ceramic stack 81 and the bridge structure connecting its two ends, it is prone to fracture and other damage when subjected to tangential stress, resulting in a high risk of product damage during product transportation, installation, and use. In the piezoelectric actuator provided in this embodiment, a filling and encapsulation layer 4 is provided between the piezoelectric structure 2 and the outer shell structure 1. This layer can improve the constraint effect on the piezoelectric structure 2 in the tangential direction when the product is subjected to tangential impact, reduce the risk of breakage of the piezoelectric structure 2 or prevent the piezoelectric structure 2 from breaking. At the same time, a protective layer 3 is also provided to reduce the constraint on the output displacement of the piezoelectric structure 2 along the first direction, reduce the resistance when the piezoelectric actuator is in motion, and effectively improve the structural stability and reliability of the product, making the piezoelectric actuator applicable to a variety of complex scenarios.

[0083] In an optional embodiment, the anti-stick layer 31 can be an oil-based coating or a nano-coating, which can effectively reduce the resistance when the piezoelectric structure 2 operates.

[0084] In an optional embodiment, referring to FIG5, the protective layer 3 further includes an elastic encapsulation layer 32, which is formed between the anti-adhesive layer 31 and the piezoelectric structure 2 and spaced apart from the filling encapsulation layer 4, for reducing the constraint when the piezoelectric structure 2 operates. Optionally, the elastic encapsulation layer 32 covers at least part of the side surface of the piezoelectric structure 2. For example, the elastic encapsulation layer 32 may cover part of the side surface of the piezoelectric structure 2 or cover the entire side surface of the piezoelectric structure 2. For example, the elastic encapsulation layer 32 covers the side surface of the piezoelectric structure 2 except for the area near the first opening 102 and the bottom of the receiving space 101. The anti-adhesive layer 31 completely covers the elastic encapsulation layer 32.

[0085] Furthermore, the elastic encapsulation layer 32 is made of an elastic material. Optionally, the elastic encapsulation layer 32 can be, for example, a polyurethane coating, a rubber coating, a graphite coating, or other suitable material coating. In practical applications, the piezoelectric structure 2 may have poor straightness along the first direction, resulting in poor linearity of movement of the piezoelectric structure 2 after potting, leading to motion obstruction. By using the elastic encapsulation layer 32 made of an elastic material, the resistance to displacement of the piezoelectric structure 2 along the first direction is further reduced, ensuring stable output of the piezoelectric actuator. It also applies elastic constraints when the piezoelectric structure 2 undergoes tangential displacement, effectively preventing damage such as breakage of the piezoelectric structure 2 when subjected to tangential impact, further improving the structural stability and reliability of the piezoelectric actuator.

[0086] In an optional embodiment, referring to FIG1, the housing structure 1 can be an integral structure or a discrete structure. For example, the housing structure 1 includes an encapsulation housing 11 and an encapsulation base 12. The encapsulation housing 11 is sleeved on the outer periphery of the encapsulation base 12 and the piezoelectric structure 2, and is spaced apart from the piezoelectric structure 2. The piezoelectric structure 2 is fixedly connected to the encapsulation base 12, which facilitates the installation and fixation of the piezoelectric structure 2. Optionally, the encapsulation housing 11 has a cylindrical structure, with one end connected to the outer side of the encapsulation base 12, so that the encapsulation housing 11 and the encapsulation base 12 form an accommodating space 101.

[0087] Furthermore, the package housing 11 may be glued to the package base 12, or fixedly connected to the package base 12 by threads, or fixedly connected to the package base 12 by welding, or fixedly connected to the package base 12 by other acceptable means.

[0088] In this embodiment, referring to Figures 6 to 9, the piezoelectric actuator is viewed from above along the first direction. The encapsulation shell 11 has a circular or rectangular ring-shaped profile, and the piezoelectric structure 2 has a circular or rectangular profile. That is, the cross-section of the encapsulation shell 11 along the first direction is a circular or rectangular ring structure, and the cross-section of the piezoelectric structure 2 along the first direction is a circular or rectangular structure.

[0089] In an optional embodiment, referring to FIG6, the piezoelectric actuator is viewed from above along the first direction. For example, the package housing 11 has an annular profile and the piezoelectric structure 2 has a rectangular profile. That is, the cross-section of the package housing 11 along the first direction is an annular structure and the cross-section of the piezoelectric structure 2 along the first direction is a rectangular structure.

[0090] In an optional embodiment, referring to FIG7, the piezoelectric actuator is viewed from above along the first direction. For example, the package housing 11 has a rectangular annular profile and the piezoelectric structure 2 has a circular profile. That is, the cross-section of the package housing 11 along the first direction is a rectangular annular structure and the cross-section of the piezoelectric structure 2 along the first direction is a circular structure.

[0091] In an optional embodiment, referring to FIG8, the piezoelectric actuator is viewed from above along a first direction. For example, the encapsulation housing 11 has a rectangular annular profile, and the piezoelectric structure 2 has a rectangular profile. That is, the cross-section of the encapsulation housing 11 perpendicular to the first direction is a rectangular annular structure, and the cross-section of the piezoelectric structure 2 perpendicular to the first direction is a rectangular structure. In practical applications, some specific scenarios require the use of a rectangular housing. When the encapsulation housing 11 with a rectangular profile and the piezoelectric structure 2 with a rectangular profile are combined, the thickness of the filling encapsulation layer 4 will be consistent, thereby making the force on the piezoelectric structure 2 more evenly distributed.

[0092] In an optional embodiment, referring to FIG9, the piezoelectric actuator is viewed from above along a first direction. For example, the encapsulation housing 11 has an annular profile, and the piezoelectric structure 2 has a circular profile. That is, the cross-section of the encapsulation housing 11 perpendicular to the first direction is an annular structure, and the cross-section of the piezoelectric structure 2 perpendicular to the first direction is a circular structure. Compared with the embodiment of FIG8, using a circular profile encapsulation housing 11 and a circular profile piezoelectric structure 2 not only makes the thickness of the filling encapsulation layer 4 consistent, but also allows for a larger area and more uniform force distribution.

[0093] It should be noted that users can make the above combinations based on factors such as application scenario, cost, and process; there is no absolutely optimal choice.

[0094] In an optional embodiment, referring to Figures 1 and 3, the transmission output structure 5 includes a transmission base 52 and a transmission output member 51. The transmission base 52 is located between the transmission output member 51 and the piezoelectric structure 2, and the transmission output member 51 is connected to the surface of the transmission base 52 away from the piezoelectric structure 2. Optionally, when the piezoelectric actuator is viewed from above along a first direction, the outer contour line of the transmission output member 51 is located within the outer contour line of the transmission base 52. The transmission output member 51 extends from the receiving space 101 through the first opening 102 and extends to the outside of the receiving space 101. The transmission output structure 5 can be an integral structure or a discrete structure. Optionally, the transmission output structure 5 adopts an integral structure, with the transmission base 52 in contact with the piezoelectric structure 2. Further, the transmission base 52 abuts against the piezoelectric structure 2, and the transmission base 52 and the piezoelectric structure 2 are fixedly connected.

[0095] Furthermore, the piezoelectric actuator also includes a cover plate 61 and an elastic element 62; the cover plate 61 is disposed along the first direction on the side of the transmission base 52 away from the piezoelectric structure 2 and is fixedly connected to the housing structure 1; the cover plate 61 and the housing structure 1 form a receiving space 101, and are spaced apart from the transmission base 52, thereby forming a movement space for the transmission base 52; a through hole 611 is provided in the cover plate 61 along the first direction, and the transmission output element 51 passes through the through hole 611 from inside the receiving space 101 and extends to the outside of the receiving space 101. Optionally, the transmission output element 51... The elastic element 62 is spaced apart from the inner wall of the through hole 611; the elastic element 62 surrounds the outer periphery of the transmission output element 51 and is located between the cover plate 61 and the transmission base 52. The elastic element 62 can apply prestress to the transmission base 52, thereby giving the transmission output structure 5 and the piezoelectric structure 2 prestress. This ensures that the transmission output structure 5 can move along the first direction to output the displacement of the piezoelectric structure 2 and reset, thus improving the structural stability and operational reliability of the piezoelectric actuator. Optionally, the elastic element 62 can be, for example, an elastic pad, a spring or other acceptable elastic element 62.

[0096] In an optional embodiment, referring to Figures 10 and 11, the filling encapsulation layer 4 includes a plurality of filling segments 41. Preferably, the plurality of filling segments 41 are arranged sequentially and evenly at intervals along the first direction. Optionally, the filling encapsulation layer 4 includes, for example, two filling segments 41, referred to as the first filling segment and the second filling segment, respectively. For example, the first filling segment may surround the end of the piezoelectric structure 2 near the first opening 102, and the second filling segment may be located between the first filling segment 41 and the encapsulation base 12; or the filling encapsulation layer 4 may include, for example, three filling segments 41, which are arranged sequentially and evenly at intervals along the first direction. By setting the filling encapsulation layer 4 as a plurality of evenly spaced filling segments 41, the contact area between the filling encapsulation layer 4 and the protective layer 3 can be reduced while ensuring the protective effect of the filling encapsulation layer 4 on the piezoelectric structure 2, thereby further reducing the resistance when the piezoelectric actuator moves along the first direction.

[0097] In an optional embodiment, referring to FIG12, the piezoelectric actuator further includes an isolation pad 7, which is located between the transmission output structure 5 and the piezoelectric structure 2. Optionally, the isolation pad 7 is fixedly connected to the piezoelectric structure 2 and makes sliding contact with the transmission output structure 5. By setting the isolation pad 7, the normal stress along the first direction and the tangential stress perpendicular to the first direction on the transmission output structure 5 are decoupled, which can protect the piezoelectric structure 2 from the tangential force on the transmission output structure 5, thereby further reducing the risk of the piezoelectric structure 2 breaking when the piezoelectric actuator is subjected to tangential impact, improving the protection effect of the piezoelectric structure 2, and helping to improve the service life of the piezoelectric actuator.

[0098] In summary, the piezoelectric actuator provided in this application supports the stroke surface of the piezoelectric structure 2 through the filling and encapsulation layer 4, effectively decomposing impact energy and preventing damage to the piezoelectric structure 2 due to excessive local stress. The anti-stick layer 31 of the protective layer 3 prevents adhesion between the filling and encapsulation layer 4 and the piezoelectric structure 2, helping to reduce the motion resistance of the piezoelectric structure 2 and ensuring the displacement output of the piezoelectric actuator. Furthermore, the protective layer 3 also includes an elastic encapsulation layer 32, which prevents hard contact between the piezoelectric structure 2 and the filling and encapsulation layer 4, reducing the constraint of the piezoelectric structure 2 in the displacement direction and further ensuring the stable output of the piezoelectric actuator. By setting the isolation gasket 7, the decoupling between the piezoelectric structure 2 and the transmission output structure 5 is achieved, further reducing the risk of breakage of the piezoelectric structure 2 and improving the service life of the piezoelectric actuator. Therefore, compared with the prior art, the piezoelectric actuator of this application can apply elastic constraints to the piezoelectric structure 2 when subjected to tangential impact or tangential stress, effectively reducing or avoiding the risk of damage to the piezoelectric structure 2. At the same time, while ensuring the protection effect of the piezoelectric structure 2, it effectively reduces the constraint of the output displacement of the piezoelectric structure 2 along the first direction, reduces the resistance when the piezoelectric actuator is in motion, improves the structural stability and reliability of the product, and improves the applicability of the piezoelectric actuator, enabling it to adapt to a variety of complex application scenarios. The solution of this application effectively overcomes the various defects in the prior art and has high industrial application value.

[0099] Example 2

[0100] This embodiment provides a packaging method for a piezoelectric actuator, used to package and form any of the piezoelectric actuators described in Embodiment 1. Referring to FIG13, the packaging method for the piezoelectric actuator provided in this embodiment includes steps S1 to S5, specifically including:

[0101] Step S1: Provide a piezoelectric structure 2, a housing structure 1 and a transmission output structure 5. The housing structure 1 has a receiving space 101, and one end of the receiving space 101 has a first opening 102.

[0102] Step S2: Form a protective layer 3 on the side of the piezoelectric structure 2;

[0103] Step S3: Fix the piezoelectric structure 2 to the bottom of the accommodating space 101;

[0104] Step S4: A filling and encapsulation layer 4 is formed between the protective layer 3 and the outer shell structure 1;

[0105] Step S5: Install the transmission output structure 5 to the first opening 102 of the housing structure 1 to output the displacement generated by the piezoelectric structure 2 along the first direction.

[0106] The packaging method of the piezoelectric actuator provided in this embodiment will be described in detail below with reference to the accompanying drawings. It should be noted that the above order does not strictly represent the process sequence of the packaging method protected by this application, and those skilled in the art can make changes according to the actual processing steps.

[0107] First, step S1 is performed, providing the piezoelectric structure 2, the housing structure 1, and the transmission output structure 5.

[0108] Specifically, the housing structure 1 has a receiving space 101 for mounting and fixing the piezoelectric structure 2. One end of the receiving space 101 has a first opening 102, which is the mounting and positioning interface and displacement output interface of the piezoelectric actuator. The piezoelectric structure 2 has a top surface and a bottom surface arranged opposite to each other, as well as a side surface connecting the top surface and the bottom surface. The piezoelectric structure 2 includes a plurality of piezoelectric elements 21, which are stacked sequentially, and the stacking direction of the plurality of piezoelectric elements 21 is taken as the first direction.

[0109] Then, step S2 is performed to form a protective layer 3 on the side of the piezoelectric structure 2.

[0110] Specifically, referring to FIG14, the protective layer 3 includes an anti-stick layer 31, which is formed by coating an anti-stick material onto the side of the piezoelectric structure 2. Optionally, the anti-stick material can be an oily material or a nanomaterial, and the thickness of the anti-stick layer 31 formed by coating is less than 50 μm.

[0111] In an optional embodiment, an anti-sticking material can be coated on a portion of the sides of the piezoelectric structure 2 to form a protective layer 3, or an anti-sticking material can be coated on all the sides of the piezoelectric structure 2 to form an anti-sticking layer 31.

[0112] Next, in step S3, the piezoelectric structure 2 is fixedly connected to the bottom of the accommodating space 101.

[0113] Specifically, referring to Figure 2, the bottom surface of the piezoelectric structure 2 can be fixedly connected to the bottom of the receiving space 101 by adhesive bonding. Optionally, adhesive material is applied to the bottom of the receiving space 101, and the piezoelectric structure 2 is placed on the adhesive material so that the piezoelectric structure 2 is fixedly connected to the bottom of the receiving space 101. Further, the piezoelectric structure 2 is connected to the central region of the bottom of the receiving space 101.

[0114] Next, step S4 is performed to form a filling encapsulation layer 4 between the protective layer 3 and the outer shell structure 1.

[0115] Specifically, referring to FIG15, a filler material is injected between the protective layer 3 and the outer shell structure 1 to form a filler encapsulation layer 4. Optionally, the filler material may be, for example, a high-rigidity encapsulating adhesive, a composite material, or other acceptable material.

[0116] Finally, step S5 is performed to install the transmission output structure 5 at the first opening 102 of the housing structure 1 to output the displacement generated by the piezoelectric structure 2 along the first direction.

[0117] In an optional embodiment, referring to FIG14, the protective layer 3 includes an anti-stick layer 31 and an elastic encapsulation layer 32. Step S2 is performed to form the protective layer 3 on the side of the piezoelectric structure 2, including the following steps: forming an elastic encapsulation layer 32 on the side of the piezoelectric structure 2; forming an anti-stick layer 31 on the surface of the elastic encapsulation layer 32, and making the anti-stick layer 31 completely cover the elastic encapsulation layer 32.

[0118] Further, an elastic material is coated onto the surface of the piezoelectric structure 2 to form an elastic encapsulation layer 32, and the elastic encapsulation layer 32 covers at least a portion of the surface of the piezoelectric structure 2. The elastic material can be, for example, polyurethane, rubber, graphite, or other acceptable materials, and the thickness of the coated elastic encapsulation layer 32 is 10 μm to 1 mm.

[0119] In an optional embodiment, the housing structure 1 includes an encapsulation housing 11 and an encapsulation base 12. Step S3, which fixes the piezoelectric structure 2 to the bottom of the accommodating space 101, includes the following steps: fixing the piezoelectric structure 2 to the encapsulation base 12; and fitting the encapsulation housing 11 around the outer periphery of the piezoelectric structure 2 and fixing it to the encapsulation base 12.

[0120] Furthermore, step S2 can be performed first, followed by step S3; or, referring to Figures 16 and 2, after the piezoelectric structure 2 is fixedly connected to the encapsulation base 12, step S2 can be performed, and then the encapsulation shell 11 can be fitted onto the outer periphery of the piezoelectric structure 2.

[0121] Furthermore, the package housing 11 and the package base 12 can be fixedly connected by adhesive bonding, or by welding, or by threading, or by other acceptable means.

[0122] In an optional embodiment, the transmission output structure 5 includes a transmission base 52 and a transmission output component 51. The piezoelectric element also includes a cover plate 61 and an elastic element 62. After step S5, the following steps are further included: fitting the elastic element 62 onto the outer periphery of the transmission output component 51; fitting the cover plate 61 onto the outer periphery of the transmission output component 51 and pressing the elastic element 62 downward toward the transmission base 52 so that the elastic element 62 abuts against the transmission base 52; and fixing the cover plate 61 to the outer shell structure 1. Optionally, the cover plate 61 is fixedly connected to the outer shell structure 1 by welding.

[0123] Furthermore, before step S5, the following step is included: applying an adhesive material to the top surface of the piezoelectric structure 2. Based on the above operations, the transmission output structure 5 and the piezoelectric structure 2 can be fixedly connected.

[0124] Further, referring to FIG10, the piezoelectric actuator also includes an isolation pad 7, and before performing step S5, the following steps are also included: applying an adhesive material to the top surface of the piezoelectric structure 2; and installing the isolation pad 7 onto the top surface of the piezoelectric structure 2 so that the isolation pad 7 and the piezoelectric structure 2 are fixedly connected.

[0125] In an optional embodiment, referring to Figures 11 and 12, the filling encapsulation layer 4 includes a plurality of filling segments 41, which are sequentially formed between the protective layer 3 and the outer shell structure 1 and spaced apart along the first direction to form the filling encapsulation layer 4.

[0126] This embodiment provides a packaging method for a piezoelectric actuator, which is used to package and form any of the piezoelectric actuators described in Embodiment 1, and therefore has the same beneficial effects as Embodiment 1.

[0127] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify, alter, or combine the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A piezoelectric actuator, characterized in that, include: The outer shell structure (1) has an internal accommodating space (101), and one end of the accommodating space (101) has a first opening (102); A piezoelectric structure (2) is located within the receiving space (101) and has a top surface and a bottom surface disposed opposite to each other, as well as a side surface connecting the top surface and the bottom surface. The bottom surface of the piezoelectric structure (2) is connected to the bottom of the receiving space (101) away from the first opening (102). The piezoelectric structure (2) includes a plurality of piezoelectric elements (21), which are stacked sequentially from the bottom of the receiving space (101) toward the direction closer to the first opening (102). The stacking direction of the plurality of piezoelectric elements (21) is taken as the first direction. A protective layer (3) is located between the outer shell structure (1) and the piezoelectric structure (2), and includes an anti-stick layer (31) that at least covers a portion of the side surface of the piezoelectric structure (2). A filling encapsulation layer (4) is located between the protective layer (3) and the outer shell structure (1), at least partially covering the protective layer (3), and spaced apart from the piezoelectric structure (2); The transmission output structure (5) is located on the side of the piezoelectric structure (2) near the first opening (102) and is used to output the displacement generated by the piezoelectric structure (2) along the first direction.

2. The piezoelectric actuator according to claim 1, characterized in that, The protective layer (3) further includes an elastic encapsulation layer (32) located between the anti-stick layer (31) and the piezoelectric structure (2), and spaced apart from the filling encapsulation layer (4). The elastic encapsulation layer (32) at least covers a portion of the side surface of the piezoelectric structure (2).

3. The piezoelectric actuator according to claim 1, characterized in that, The filling and encapsulation layer (4) includes a plurality of filling segments (41), which are arranged sequentially at intervals along the first direction.

4. The piezoelectric actuator according to claim 1, characterized in that, The outer shell structure (1) includes an encapsulation shell (11) and an encapsulation base (12). The bottom surface of the piezoelectric structure (2) is connected to the encapsulation base (12). The first opening (102) is disposed at one end of the encapsulation shell (11). The end of the encapsulation shell (11) away from the first opening (102) is connected to the encapsulation base (12), so that the encapsulation shell (11) is sleeved on the outer periphery of the encapsulation base (12) and the piezoelectric structure (2), and the encapsulation shell (11) and the piezoelectric structure (2) are spaced apart.

5. The piezoelectric actuator according to claim 4, characterized in that, Viewed from above along the first direction, the piezoelectric actuator has an annular or rectangular annular profile, and the piezoelectric structure (2) has a circular or rectangular profile.

6. The piezoelectric actuator according to claim 1, characterized in that, The transmission output structure (5) includes a transmission base (52) and a transmission output member (51), wherein the transmission output member (51) is connected to the surface of the transmission base (52) away from the piezoelectric structure (2); wherein, when the piezoelectric actuator is viewed from above along the first direction, the outer contour line of the transmission output member (51) is located within the outer contour line of the transmission base (52).

7. The piezoelectric actuator according to claim 6, characterized in that, The piezoelectric actuator also includes: A cover plate (61) is spaced along the first direction on the side of the transmission base (52) away from the piezoelectric structure (2) and is fixedly connected to the outer shell structure (1). The cover plate (61) has a through hole (611) that runs through the first direction. The transmission output member (51) passes through the through hole (611). An elastic element (62) surrounds the outside of the transmission output element (51) and is located between the cover plate (61) and the transmission base (52).

8. The piezoelectric actuator according to claim 1, characterized in that, The piezoelectric actuator further includes an isolation pad (7), which is located between the transmission output structure (5) and the piezoelectric structure (2), and is connected to the piezoelectric structure (2) and has sliding contact with the transmission output structure (5).

9. The piezoelectric actuator according to claim 1, characterized in that, The outer shell structure (1) is a metal workpiece or a ceramic workpiece to protect the piezoelectric structure (2); or, the piezoelectric element (21) is a piezoelectric ceramic monolith; or, the material of the filling encapsulation layer (4) is a high-rigidity encapsulating adhesive or a composite material; or, the transmission output structure (5) is spaced apart from the sidewall of the first opening (102).

10. The piezoelectric actuator according to claim 2, characterized in that, The anti-stick layer (31) is an oil-based coating or a nano-coating; and / or, the elastic encapsulation layer (32) is made of an elastic material.

11. The piezoelectric actuator according to claim 1, characterized in that, The outer shell structure (1) is an integral structure or a discrete structure; and / or, the transmission output structure (5) is an integral structure or a discrete structure.

12. The piezoelectric actuator according to claim 4, characterized in that, The encapsulation shell (11) can be bonded to the encapsulation base (12), or fixedly connected to the encapsulation base (12) by threads, or fixedly fixed to the encapsulation base (12) by welding.

13. A method for packaging a piezoelectric actuator, used to package and form the piezoelectric actuator according to any one of claims 1 to 12, characterized in that, Includes the following steps: A piezoelectric structure (2), a housing structure (1) and a transmission output structure (5) are provided. The housing structure (1) has a receiving space (101) and a first opening (102) is provided at one end of the receiving space (101). A protective layer (3) is formed on the side of the piezoelectric structure (2); The piezoelectric structure (2) is fixedly connected to the bottom of the receiving space (101); A filling and encapsulation layer (4) is formed between the protective layer (3) and the outer shell structure (1); The transmission output structure (5) is installed at the first opening (102) of the housing structure (1) to output the displacement generated by the piezoelectric structure along the first direction.

14. The packaging method for the piezoelectric actuator according to claim 13, characterized in that, The protective layer (3) includes an anti-stick layer (31) and an elastic encapsulation layer (32). The formation of the protective layer (3) on the side of the piezoelectric structure (2) includes the following steps: An elastic encapsulation layer (32) is formed on the side of the piezoelectric structure (2); The anti-stick layer (31) is formed on the surface of the elastic encapsulation layer (32) and the anti-stick layer (31) completely covers the elastic encapsulation layer (32).

15. The packaging method for the piezoelectric actuator according to claim 13, characterized in that, The housing structure (1) includes an encapsulation housing (11) and an encapsulation base (12). The step of fixing the piezoelectric structure (2) to the bottom of the receiving space (101) includes the following steps: The piezoelectric structure (2) is fixedly connected to the encapsulation base (12); The encapsulation shell (11) is fitted onto the outer periphery of the piezoelectric structure (2) and fixedly connected to the encapsulation base (12).

16. The packaging method for the piezoelectric actuator according to claim 13, characterized in that, The transmission output structure (5) includes a transmission base (52) and a transmission output component (51). The piezoelectric actuator also includes a cover plate (61) and an elastic component (62). After the transmission output structure (5) is installed at the first opening (102) of the housing structure (1), the following steps are also included: The elastic element (62) is sleeved on the outer periphery of the transmission output element (51); The cover plate (61) is fitted onto the outer periphery of the transmission output member (51), and the elastic member (62) is pressed down toward the transmission base (52) so that the elastic member (62) abuts against the transmission base (52); The cover plate (61) is fixedly connected to the outer shell structure (1).

17. The packaging method for the piezoelectric actuator according to claim 14, characterized in that, The step of forming the anti-stick layer (31) on the surface of the elastic encapsulation layer (32) includes: An anti-adhesive material is applied to the side surface of the piezoelectric structure (2) to form the anti-adhesive layer (31), or the anti-adhesive material is applied to a portion of the side surface of the piezoelectric structure (2) to form the anti-adhesive layer (31), wherein the anti-adhesive material is an oil-based material or a nanomaterial, and the thickness of the anti-adhesive layer (31) is less than 50 μm; and / or, The step of forming an elastic encapsulation layer (32) on the side of the piezoelectric structure (2) includes: An elastic material is applied to the surface of the piezoelectric structure (2) to form the elastic encapsulation layer (32) such that the elastic encapsulation layer (32) covers at least a portion of the surface of the piezoelectric structure (2); The elastic material is polyurethane, rubber, or graphite, and the thickness of the elastic encapsulation layer (32) is 10 μm to 1 μm.

18. The packaging method for a piezoelectric actuator according to claim 13, characterized in that, The step of fixing the piezoelectric structure (2) to the bottom of the receiving space (101) includes: The bottom surface of the piezoelectric structure (2) is fixedly connected to the bottom of the receiving space (101) by bonding, or an adhesive material is applied to the bottom of the receiving space (101), and the piezoelectric structure (2) is placed on the adhesive material so that the piezoelectric structure (2) is fixedly connected to the bottom of the receiving space (101), wherein the piezoelectric structure (2) is connected to the central region of the bottom of the receiving space (101).

19. The packaging method for a piezoelectric actuator according to claim 15, characterized in that, The steps of fitting the encapsulation shell (11) onto the outer periphery of the piezoelectric structure (2) and fixing it to the encapsulation base (12) include: The encapsulation shell (11) and the encapsulation base (12) are fixedly connected by adhesive bonding, or the encapsulation shell (11) and the encapsulation base (12) are fixedly connected by welding, or the encapsulation shell (11) and the encapsulation base (12) are fixedly connected by threads.

20. The packaging method for a piezoelectric actuator according to claim 13, characterized in that, The piezoelectric actuator further includes an isolation pad (7), and the step of mounting the transmission output structure (5) to the first opening (102) of the housing structure (1) includes: An adhesive material is applied to the top surface of the piezoelectric structure (2); The isolation pad (7) is installed on the top surface of the piezoelectric structure (2) so that the isolation pad (7) and the piezoelectric structure (2) are fixedly connected.

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