piezoelectric actuator

Abstract

The application relates to the piezoelectric technology field and discloses a piezoelectric actuating device. The piezoelectric actuating device comprises a seat body, a piezoelectric device and a buffer structure; the piezoelectric device comprises a fixed area and a free area connected along a first direction; along a second direction, the seat body, the buffer structure and the fixed area are sequentially fixedly connected, along the first direction, the free area protrudes from the seat body and the buffer structure, and the second direction intersects the first direction. Wherein, the hardness of the buffer structure is less than the hardness of the seat body, the buffer structure comprises a first buffer area and a second buffer area sequentially connected along the first direction, along the first direction, the first buffer area is farther away from the free area than the second buffer area, and the hardness of the first buffer area is greater than the hardness of the second buffer area. In this way, the stress concentration phenomenon of the piezoelectric actuating device can be reduced, the service life of the piezoelectric actuating device is prolonged, and the thrust generated by the piezoelectric actuating device is increased.

Description

Technical Field

[0001] This application relates to the field of piezoelectric technology, and in particular to a piezoelectric actuator. Background Technology

[0002] With the development of electronic technology, piezoelectric actuators (also known as piezoelectric actuators or piezoelectric drivers) have become one of the core components of precision control due to the piezoelectric effect of piezoelectric materials. They are widely used in fields such as optical path control, high-precision positioning, and rapid workpiece deflection. The piezoelectric effect refers to the effect of applying an electric field inside a piezoelectric material, causing strain or stress within the material, and subsequently generating macroscopic mechanical force and deformation. This piezoelectric effect enables piezoelectric actuators to output displacement and generate thrust.

[0003] However, current piezoelectric actuators have a short lifespan and generate relatively low thrust even at high drive voltages, limiting the overall performance improvement of piezoelectric actuators. Utility Model Content

[0004] To solve the above-mentioned technical problems, this application provides a piezoelectric actuator. The following describes this application from multiple aspects, and the implementation methods and beneficial effects of the following aspects can be referred to each other.

[0005] In a first aspect, this application provides a piezoelectric actuator, which includes a base, a piezoelectric element, and a buffer structure. The piezoelectric element includes a fixed region and a free region connected along a first direction. Along a second direction, the base, buffer structure, and fixed region are sequentially fixedly connected. Along the first direction, the free region protrudes from the base and buffer structure. The second direction intersects the first direction. The buffer structure has a lower hardness than the base. The buffer structure includes a first buffer zone and a second buffer zone sequentially connected along the first direction. Along the first direction, the first buffer zone is further away from the free region than the second buffer zone, and the hardness of the first buffer zone is greater than that of the second buffer zone.

[0006] Thus, because the first buffer zone is harder than the second buffer zone, it provides appropriate support stiffness for the piezoelectric device, ensuring a stable deformation basis when the free region undergoes bending deformation. This makes it easier for the piezoelectric device to generate a larger output displacement under the electric field excitation of the driving voltage. The second buffer zone has better flexibility and deformation capacity, effectively releasing the stress generated in the fixed region due to assembly or force. Furthermore, the second buffer zone can increase the overall output displacement of the piezoelectric device, thereby improving the service life and output performance of the piezoelectric actuator.

[0007] In some implementations of the first aspect mentioned above, the buffer structure also includes a third buffer. Along the first direction, the first buffer, the second buffer, and the third buffer are connected in sequence, and the hardness of the first buffer, the second buffer, and the third buffer decreases in sequence.

[0008] Thus, since the buffer structure consists of three buffer zones of different hardness connected sequentially along the first direction, a gradient distribution of hardness is formed, gradually decreasing from the fixed area to the free area. That is, the first buffer zone has the highest hardness, providing strong support and constraint for the piezoelectric device, ensuring its stable fixation and reducing additional displacement. The second buffer zone in the middle has moderate hardness, serving as a transition. The third buffer zone has the lowest hardness, possessing superior flexibility and deformation capacity. It not only effectively releases stress within the piezoelectric device but also provides greater bending deformation space, making it easier to deform during driving, thereby improving the overall output displacement. Therefore, the technical solution of this application, through the gradient hardness layout of the buffer structure, balances the structural stability and reliability of the piezoelectric actuator with its dynamic deformation flexibility, which is beneficial to improving the stability, reliability, and output performance of the piezoelectric actuator.

[0009] In some implementations of the first aspect described above, the piezoelectric device includes a first piezoelectric layer and a second piezoelectric layer stacked together along a second direction, wherein the second piezoelectric layer is stacked together with a buffer structure along the second direction. The first piezoelectric layer includes at least one first piezoelectric functional layer and at least one first electrode layer alternately stacked along the second direction, and the second piezoelectric layer includes at least one second piezoelectric functional layer and at least one second electrode layer alternately stacked along the second direction. Specifically, the number of first piezoelectric functional layers in the first piezoelectric layer is 15 to 25; and / or, the number of second piezoelectric functional layers in the second piezoelectric layer is 4 to 10.

[0010] Thus, the appropriate number of the first and second piezoelectric functional layers ensures that the piezoelectric device maintains an appropriate overall thickness, preventing excessive thickness from causing excessive stiffness and thereby improving the dynamic performance of the piezoelectric device.

[0011] In some implementations of the first aspect described above, the dimensions of each first piezoelectric functional layer along the second direction are from 5 micrometers (μm) to 15 μm. The dimensions of each second piezoelectric functional layer along the second direction are greater than or equal to 120 μm, and the second piezoelectric layer is used to receive a driving voltage opposite to the polarization direction of the second piezoelectric functional layer.

[0012] Thus, due to the smaller thickness of the first piezoelectric functional layer, the spacing between adjacent first electrode layers can be reduced, thereby increasing the electric field strength. This allows for increased thrust and output displacement even when the driving voltage received by the piezoelectric device is reduced, for example, from 150 volts (V) to 24V. Furthermore, since the electric field direction of the second piezoelectric layer is opposite to its own polarization, setting the thickness of the second piezoelectric functional layer to be greater than or equal to 120 μm ensures that the depolarization voltage of the second piezoelectric layer is much higher than the driving voltage (e.g., 24V in a low-voltage system), thereby guaranteeing the long-term safe use of the piezoelectric device.

[0013] In some implementations of the first aspect described above, the material of the first piezoelectric functional layer is piezoelectric ceramic. It should be noted that the material of the first piezoelectric functional layer can also be other materials with piezoelectric effects, and this application does not impose any restrictions on this.

[0014] In some implementations of the first aspect described above, the material of the second piezoelectric functional layer is piezoelectric ceramic. It should be noted that the material of the second piezoelectric functional layer can also be other materials with piezoelectric effects, and this application does not impose any restrictions on this.

[0015] In some implementations of the first aspect described above, the first piezoelectric layer is a monolithic structure. For example, the first piezoelectric layer can be prepared by a multilayer co-firing method, that is, the first piezoelectric functional layer and the first electrode layer can be prepared by a co-firing method to form the first piezoelectric layer, thereby improving the overall strength and stability of the first piezoelectric layer.

[0016] In some implementations of the first aspect described above, the second piezoelectric layer is an integral structure. The second piezoelectric layer can be fabricated using a multilayer co-firing method, meaning that the second piezoelectric functional layer and the second electrode layer can be co-fired to form the second piezoelectric layer, thereby improving the overall strength and stability of the second piezoelectric layer.

[0017] In some implementations of the first aspect described above, the piezoelectric device includes a piezoelectric bicrystalline wafer, with a first direction being the length direction of the piezoelectric bicrystalline wafer, a second direction being the thickness direction of the piezoelectric bicrystalline wafer, and a third direction being the width direction of the piezoelectric bicrystalline wafer. Furthermore, the first direction, the second direction, and the third direction are mutually perpendicular. In other embodiments, the first direction, the second direction, and the third direction may be other directions, and this application does not impose any limitations on this.

[0018] In some implementations of the first aspect described above, the Shore hardness of the buffer structure is between 40 and 75. For example, the Shore hardness of the buffer structure can be 40, 45, 50, 55, 60, 65, 70, or 75, etc. It should be noted that the buffer structure can also be set to other hardnesses as needed, and this application does not impose any restrictions on this.

[0019] In this way, the buffer structure can combine appropriate flexibility and stiffness, thereby effectively absorbing the impact and vibration from the piezoelectric device when it generates output displacement, and also providing stable support for the piezoelectric device, thereby increasing the output displacement and reducing stress while ensuring the resonant frequency. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0021] Figure 1 A schematic diagram (perspective view) of a piezoelectric actuator in the prior art is shown;

[0022] Figure 2 A schematic diagram (perspective view) of a piezoelectric actuator in the prior art is shown;

[0023] Figure 3 A schematic diagram (cross-sectional view) of a piezoelectric actuator in the prior art is shown;

[0024] Figure 4 A schematic diagram (cross-sectional view) of an optional piezoelectric actuator according to an embodiment of this application is shown;

[0025] Figure 5A and Figure 5B Schematic diagrams (cross-sectional views) of a piezoelectric actuator in the prior art and an optional piezoelectric actuator in an embodiment of this application are shown respectively;

[0026] Figure 6 A schematic diagram (cross-sectional view) of an optional piezoelectric device according to an embodiment of this application is shown.

[0027] Explanation of reference numerals in the attached figures:

[0028] 01. Piezoelectric actuator; 11. Base; 111. Fixing through hole; 112. Groove; 112a. Mounting surface; 12. Piezoelectric bicrystalline wafer; 12a. Interface; 121. First piezoelectric ceramic sheet; 122. Passive structure layer; 123. Second piezoelectric ceramic sheet; 13. Lead wire;

[0029] 02. Piezoelectric actuator; 21. Base; 211. Main body; 21a. First surface; 212. Limiting part; 22. Piezoelectric device; 221. Fixed area; 222. Free area; 223. First piezoelectric layer; 224. Second piezoelectric layer; 23. Buffer structure; 231. First buffer zone; 232. Second buffer zone; 233. Third buffer zone. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0031] As mentioned earlier, piezoelectric actuators have a relatively short lifespan and produce relatively low thrust even at higher drive voltages. The following section combines... Figures 1 to 3 Please provide a detailed explanation.

[0032] Figure 1 A perspective view of the piezoelectric actuator 01 is shown; Figure 2 Another perspective view of the piezoelectric actuator 01 is shown, specifically a schematic diagram of the piezoelectric actuator 01 when it outputs displacement outward; Figure 3 A cross-sectional view of the piezoelectric actuator 01 is shown.

[0033] To facilitate the subsequent description, before introducing the specific structure of the piezoelectric actuator 01, let's first combine... Figure 1 Define the x-axis, y-axis, and z-axis directions corresponding to piezoelectric actuator 01. For example... Figure 1 As shown, the x-axis direction can be the length direction of the piezoelectric actuator 01, or the length direction of the base 11 and the length direction of the piezoelectric bicrystalline wafer 12. The y-axis direction can be the width direction of the piezoelectric actuator 01, or the width direction of the base 11 and the width direction of the piezoelectric bicrystalline wafer 12. The z-axis direction can be the thickness direction of the piezoelectric actuator 01, or the thickness direction of the base 11 and the thickness direction of the piezoelectric bicrystalline wafer 12. In some embodiments of this application, the x-axis, y-axis, and z-axis directions intersect each other. In some implementations, the x-axis, y-axis, and z-axis directions can be perpendicular to each other.

[0034] It should be noted that the directional terms such as "upper," "lower," "left," "right," "top," "bottom," and "above" used in this document refer to exemplary orientations shown in the accompanying drawings corresponding to the embodiments, and do not indicate or imply that the components referred to must have a specific orientation. These terms can vary accordingly based on actual use and should not be construed as limiting this application. Furthermore, it is understood that when the viewing angle of the accompanying drawings changes (e.g., the drawings are rotated at any angle for reference), the directional terms also change accordingly.

[0035] It is understood that the perpendicularity in this application is not absolute perpendicularity. Approximate perpendicularity due to processing and assembly errors (e.g., an angle of 89° between two structural features) is also within the scope of mutual perpendicularity in this application. Similarly, the parallelism in this application is not absolute parallelism. Approximate parallelism due to processing and assembly errors (e.g., an angle of 1° between two structural features) is also within the scope of mutual parallelism in this application. The limitations of mutual parallelism and mutual perpendicularity will not be repeated below.

[0036] Reference in the prior art Figures 1 to 3The piezoelectric actuator 01 may include a base 11 and a piezoelectric bicrystalline wafer 12. The base 11 has fixing through holes 111 and grooves 112 spaced apart along the x-axis. The number of fixing through holes 111 can be one or more (e.g., two), used to install fasteners to fix the base 11. The bottom wall of the groove 112 forms a mounting surface 112a. One end of the piezoelectric bicrystalline wafer 12 along the x-axis is fixed to the mounting surface 112a, for example, by adhesive bonding; that is, this end of the piezoelectric bicrystalline wafer 12 is the fixed end (or fixed area). The other end of the piezoelectric bicrystalline wafer 12 along the x-axis is the free end (or free area). The piezoelectric bicrystalline wafer 12 can be considered as consisting of a fixed area and a free area connected along the x-axis.

[0037] The piezoelectric actuator 01 may further include three leads 13, which are respectively connected to three interfaces 12a on the piezoelectric bicrystalline wafer 12 to drive the piezoelectric bicrystalline wafer 12. Specifically, the piezoelectric bicrystalline wafer 12 may include a first piezoelectric ceramic sheet 121, a passive structure layer 122, and a second piezoelectric ceramic sheet 123 stacked sequentially along the z-axis. The three interfaces 12a are respectively connected to the first piezoelectric ceramic sheet 121, the passive structure layer 122, and the second piezoelectric ceramic sheet 123. The material of the passive structure layer 122 may be carbon fiber, metal, or ceramic, etc.

[0038] The working principle of the piezoelectric actuator 01 is as follows: The first piezoelectric ceramic sheet 121 and the second piezoelectric ceramic sheet 123 have the same polarization direction. By inputting a positive bias voltage and 0 volts (V) to the first piezoelectric ceramic sheet 121 and the passive structure layer 122 respectively through the lead 13 and interface 12a, the first piezoelectric ceramic sheet 121 becomes thicker in the z-axis direction and shorter in the x-axis direction, thus causing the piezoelectric bicrystalline wafer 12 to tilt upwards, resulting in upward displacement. By inputting a positive bias voltage and 0V to the passive structure layer 122 and the second piezoelectric ceramic sheet 123 respectively through the lead 13 and interface 12a, the second piezoelectric ceramic sheet 123 becomes thicker in the z-axis direction and shorter in the x-axis direction, thus causing the piezoelectric bicrystalline wafer 12 to bend downwards, resulting in downward displacement. The above two driving methods are single-sided control methods. In other embodiments, a differential pressure control method can also be used: a fixed positive bias voltage and 0V are respectively input to the first piezoelectric ceramic sheet 121 and the second piezoelectric ceramic sheet 123, while a varying positive bias voltage is input to the passive structure layer 122. This varying positive bias voltage is located between the voltages of the first piezoelectric ceramic sheet 121 and the second piezoelectric ceramic sheet 123, thereby enabling the first piezoelectric ceramic sheet 121 and the second piezoelectric ceramic sheet 123 to deform simultaneously, so that the piezoelectric bicrystalline wafer 12 as a whole outputs an upward or downward displacement.

[0039] Continue to refer to Figure 2 and Figure 3Since the piezoelectric bicrystalline wafer 12 is a rigid device, and as mentioned earlier, the fixed area of ​​the piezoelectric bicrystalline wafer 12 is fixed to the base 11 by bonding, a stress concentration point will be generated at the bonding area between the fixed area of ​​the piezoelectric bicrystalline wafer 12 and the base 11 as the fixed area of ​​the piezoelectric bicrystalline wafer 12 continuously generates outward output displacement. Furthermore, as the piezoelectric bicrystalline wafer 12 is used (operated), the stress at this stress concentration point will continuously accumulate, making the piezoelectric bicrystalline wafer 12 prone to fracture, with a short lifespan, and unable to be used for a long time.

[0040] Furthermore, the piezoelectric bicrystalline wafer 12 generates thrust (or resistance) while outputting displacement to drive the load. For example, in some applications, a piezoelectric actuator 01 can be used to replace a solenoid valve. Compared to a solenoid valve, the piezoelectric actuator 01 has a faster response speed, lower power consumption, and longer lifespan. However, since high thrust requires high material stiffness to generate a large force, but high stiffness limits deformation and reduces displacement, the piezoelectric bicrystalline wafer 12 cannot simultaneously achieve high thrust and large displacement. Therefore, even when a high driving voltage (e.g., 150 volts (V)) is applied to the piezoelectric bicrystalline wafer 12, the thrust is still relatively small (e.g., less than 1.5 Newtons (N)). Moreover, at higher driving voltages, the piezoelectric bicrystalline wafer 12 may experience discharge breakdown, thus affecting the performance of the piezoelectric actuator 01.

[0041] To address the aforementioned problems, this application provides a piezoelectric actuator. In this actuator, the piezoelectric device includes a fixed region and a free region connected along the x-axis. A buffer structure connects the fixed region of the piezoelectric device, such as the base and the piezoelectric bicrystalline wafer. The buffer structure includes at least two buffer zones with different hardnesses, which are sequentially connected along the x-axis. The buffer zone closer to the free region has a higher hardness than the buffer zone farther from the free region.

[0042] Thus, the buffer structure is composed of non-rigid materials with varying hardness, creating a hardness gradient distribution along the x-axis. This results in a lower hardness buffer near the free zone, providing better flexibility and deformation capacity, effectively releasing stress generated at the fixed end due to assembly or force, and preventing excessive local stress that could lead to piezoelectric device breakage. Conversely, the higher hardness buffer further from the free zone provides appropriate support stiffness for the piezoelectric device, ensuring a stable deformation basis during bending deformation in the free zone. This allows the piezoelectric device to more easily generate a larger output displacement under the electric field excitation of the driving voltage. Therefore, the technical solution of this application can increase the output displacement of the piezoelectric device while alleviating stress, thereby improving the reliability and output performance of the piezoelectric actuator.

[0043] The following is combined with Figures 4 to 6 An exemplary structure of a piezoelectric actuator in some embodiments of this application is described.

[0044] Figure 4 A cross-sectional view of the piezoelectric actuator 02 is shown, specifically a cross-sectional view of the xz plane. Figure 5A and Figure 5B Cross-sectional views of piezoelectric actuator 01 and piezoelectric actuator 02 are shown, specifically cross-sectional views of the xz plane, and schematic diagrams of the piezoelectric actuator generating outward output displacement.

[0045] It should be noted that the direction definition of the piezoelectric actuator 02 is the same as that of the piezoelectric actuator 01. Please refer to the relevant content of the piezoelectric actuator 01 mentioned above, and it will not be repeated here.

[0046] refer to Figure 4 The piezoelectric actuator 02 includes a base 21, a piezoelectric element 22, and a buffer structure 23. The piezoelectric element 22 includes a fixed region 221 and a free region 222 connected along the x-axis (as an example of a first direction). Along the z-axis (as an example of a second direction), the base 21, the buffer structure 23, and the fixed region 221 are sequentially fixedly connected, and along the x-axis, the free region 222 protrudes from the base 21 and the buffer structure 23. The buffer structure 23 has a lower hardness than the base 21. The buffer structure 23 includes a first buffer zone 231 and a second buffer zone 232 sequentially connected along the x-axis. Along the x-axis, the first buffer zone 231 is further away from the free region 222 than the second buffer zone 232, and the hardness of the first buffer zone 231 is greater than that of the second buffer zone 232.

[0047] Thus, since the hardness of the first buffer zone 231 is greater than that of the second buffer zone 232, the first buffer zone 231 can provide appropriate support stiffness for the piezoelectric device 22, ensuring that the free region 222 has a stable deformation basis when bending deformation occurs, making it easier for the piezoelectric device 22 to generate a larger output displacement under the electric field excitation of the driving voltage. The second buffer zone 232 has better flexibility and deformation capability, which can effectively release the stress generated in the fixed region 221 due to assembly or force. In addition, the second buffer zone 232 can also increase the overall output displacement of the piezoelectric device 22, thereby improving the service life and output performance of the piezoelectric actuator 02.

[0048] In this embodiment, the x-axis, y-axis, and z-axis directions can be mutually perpendicular. Furthermore, the x-axis can be the length direction of the piezoelectric device 22, the y-axis can be the width direction of the piezoelectric device 22, and the z-axis can be the thickness direction of the piezoelectric device 22. It should be noted that in this embodiment, the first direction can be the x-axis, the second direction can be the z-axis, and the third direction can be the y-axis, but this application is not limited to these. In other embodiments, the first direction, the second direction, and the third direction can be other directions, and this application does not impose any restrictions on these.

[0049] In some embodiments, continue to refer to Figure 4 The buffer structure 23 also includes a third buffer 233. Along the x-axis, the first buffer 231, the second buffer 232 and the third buffer 233 are connected in sequence, and the hardness of the first buffer 231, the second buffer 232 and the third buffer 233 decreases in sequence.

[0050] Thus, since the buffer structure 23 consists of three buffers of different hardness connected sequentially along the x-axis, a gradient distribution of hardness is formed, with the hardness gradually decreasing from the fixed region 221 to the free region 222. That is, the first buffer 231 has the highest hardness, providing strong support and constraint for the piezoelectric device 22, ensuring its stable fixation and reducing additional displacement. The second buffer 232 has moderate hardness, serving as a transition. The third buffer 233 has the lowest hardness, possessing superior flexibility and deformation capacity. It not only effectively releases stress within the piezoelectric device 22, preventing stress concentration, but also provides a larger bending deformation space for the piezoelectric device 22, making it easier to deform during driving, thereby improving the overall output displacement. Therefore, the technical solution of this application, through the gradient hardness layout of the buffer structure, balances the structural stability and reliability of the piezoelectric actuator 02 with its dynamic deformation flexibility, which is beneficial to improving the stability, reliability, and output performance of the piezoelectric actuator 02.

[0051] As can be seen, in this embodiment, the bottom surface of the buffer structure 23 can be fixedly connected to the base 21, and the top surface of the buffer structure 23 can be fixedly connected to the piezoelectric device 22. Furthermore, the contact area between the piezoelectric device 22 and the buffer structure 23 can be referred to as the fixed area 221 of the piezoelectric device 22. It can be understood that, with the overall length of the piezoelectric device 22 remaining constant, by adjusting the size of the contact area between the piezoelectric device 22 and the buffer structure 23, the length of the fixed area 221 and the length of the free area 222 in the piezoelectric device 22 can be adjusted. Since the length of the free area 222 is related to both the resonant frequency and the output displacement, the resonant frequency and output displacement of the piezoelectric actuator 02 can be adjusted according to requirements.

[0052] In some embodiments, the Shore hardness of the buffer structure 23 is 40 to 75. For example, the Shore hardness of the buffer structure 23 can be 40, 45, 50, 55, 60, 65, 70, or 75, etc. It should be noted that the buffer structure 23 can also be set to other hardnesses as needed, and this application does not impose any limitations on this.

[0053] Thus, the buffer structure 23 can combine appropriate flexibility and rigidity, thereby effectively absorbing the impact and vibration from the piezoelectric device 22 when it generates output displacement, and also providing stable support for the piezoelectric device 22, thereby increasing the output displacement and reducing stress while ensuring the resonant frequency.

[0054] In some embodiments, the buffer structure 23 includes at least one of a rubber pad and a silicone pad. For example, the buffer structure 23 can be a polyurethane rubber pad, a soft silicone pad, or a rubber damping pad, etc. It should be noted that the buffer structure 23 may also include other non-rigid materials to provide stress buffering and structural support for the piezoelectric device 22, and this application does not impose any limitations on this.

[0055] In some embodiments, the seat 21, the buffer structure 23, and the fixing area 221 are sequentially fixedly connected. The connection method between the seat 21 and the buffer structure 23 is adhesive bonding, such as bonding with an adhesive, to improve the fixing stability between the seat 21 and the buffer structure 23. It should be noted that this application does not impose any restrictions on the connection method between the seat 21 and the buffer structure 23, and the seat 21 and the buffer structure 23 can also be fixedly connected in other ways.

[0056] In some embodiments, the connection between the buffer structure 23 and the fixing area 221 is by bonding, for example, using an adhesive, to improve the stability of the connection between the buffer structure 23 and the fixing area 221. It should be noted that this application does not impose any restrictions on the connection method between the buffer structure 23 and the fixing area 221; other methods can also be used for the fixed connection between the buffer structure 23 and the fixing area 221.

[0057] refer to Figure 5A and Figure 5B It can be seen that Figure 5A The piezoelectric actuator 01 is a piezoelectric actuator without a buffer structure. The piezoelectric actuator 01 includes a base 11 and a piezoelectric bicrystalline wafer 12. Figure 5B The piezoelectric actuator 02 provided in this application employs a buffer structure 23 with a gradient hardness layout. (And...) Figure 5A Compared to the piezoelectric actuator 01, Figure 5BThe piezoelectric actuator 02 incorporates a buffer structure 23 with a hardness gradient between the fixed region 221 and the base 21. This allows the fixed region 221 to have sufficient deformation space under load, reducing the limitation imposed by the fixed constraint on the deformation of the piezoelectric device 22. This makes the free region 222 more prone to bending or stretching deformation under electric field excitation, thereby increasing the output displacement of the free region 222. Simultaneously, the buffer structure 23 can absorb the stress generated in the fixed region 221 during dynamic operation, thus improving the reliability and service life of the piezoelectric actuator 02.

[0058] The following is combined with Figure 6 An exemplary structure of the piezoelectric device 22 is described.

[0059] Figure 6 A cross-sectional view of a piezoelectric device 22 is shown, specifically a cross-sectional view of the xz plane.

[0060] In some embodiments, the piezoelectric device 22 may be a piezoelectric bicrystalline wafer. In other embodiments, the piezoelectric device 22 may also be other devices with piezoelectric effect, and this application does not limit this.

[0061] It should be noted that this application does not limit the specific size of the piezoelectric device 22, and those skilled in the art can choose a suitable size according to actual needs.

[0062] refer to Figure 6 and combined Figure 4 In some embodiments, the piezoelectric device 22 includes a first piezoelectric layer 223 and a second piezoelectric layer 224 stacked along the z-axis (as an example of a second direction), and the second piezoelectric layer 224 is stacked with the buffer structure 23 along the z-axis. The first piezoelectric layer 223 includes at least one first piezoelectric functional layer and at least one first electrode layer (not shown) alternately stacked along the z-axis, and the second piezoelectric layer 224 includes at least one second piezoelectric functional layer and at least one second electrode layer (not shown) alternately stacked along the z-axis.

[0063] In some embodiments, the piezoelectric device 22 may also be provided with a plurality of at least one interface (not shown), and the piezoelectric actuator 02 may also include leads connected to the interfaces one by one for providing driving voltages to the first piezoelectric layer 223 and the second piezoelectric layer 224 of the piezoelectric device 22, respectively.

[0064] The first electrode layer is used to receive the driving voltage applied to the first piezoelectric layer 223 and form an electric field that drives the deformation of the first piezoelectric functional layer. The first piezoelectric functional layer is used to deform under the excitation of the electric field. Specifically, the first electrode layer receives a driving voltage (or unidirectional voltage) with the same polarization direction as the first piezoelectric functional layer, so that the thickness (dimension along the z-axis) of the entire first piezoelectric layer 223 increases and the length (dimension along the x-axis) decreases when the driving voltage is received. The second electrode layer is used to receive the driving voltage applied to the second piezoelectric layer 224 and form an electric field that drives the deformation of the second piezoelectric functional layer. The second piezoelectric functional layer is used to deform under the excitation of the electric field. Specifically, the second electrode layer receives a driving voltage (or reverse voltage) with the opposite polarization direction to the second piezoelectric functional layer, so that the thickness (dimension along the z-axis) of the entire second piezoelectric layer 224 decreases and the length (dimension along the x-axis) increases when the driving voltage is received. Thus, when a driving voltage is applied to the piezoelectric device 22, the first piezoelectric layer 223 thickens in the thickness direction and shortens in the length direction, resulting in an upward (positive z-axis direction) bending effect. Therefore, the first piezoelectric layer 223 can be called a positive tension layer or a positive push layer. The second piezoelectric layer 224 thins in the thickness direction and lengthens in the length direction, also resulting in an upward bending effect. Therefore, the second piezoelectric layer 224 can be called a reverse push layer. Since the first piezoelectric layer 223 and the second piezoelectric layer 224 exert upward force simultaneously, the piezoelectric device 22 can undergo strong bending deformation, doubling the thrust when generating upward output displacement. The principle of the piezoelectric device 22 generating downward output displacement is the same as the principle of generating upward output displacement, and will not be repeated here. Thus, the piezoelectric actuator 02 provided in this application can output large thrust and high displacement at a relatively small driving voltage (e.g., 24V).

[0065] In some embodiments, the first piezoelectric functional layer and the second piezoelectric functional layer have the same polarization direction, for example, both facing the negative z-axis direction. Accordingly, the first piezoelectric layer 223 is used to receive a driving voltage with the electric field direction downward, and the second piezoelectric layer 224 is used to receive a driving voltage with the electric field direction upward. It should be noted that the polarization direction of the first piezoelectric functional layer and the second piezoelectric functional layer can also both be facing the positive z-axis direction, and the direction of the driving voltage can also be adaptively changed. This application does not limit this.

[0066] In some embodiments, the number of first piezoelectric functional layers in the first piezoelectric layer 223 can be 15 to 25; and the number of second piezoelectric functional layers in the second piezoelectric layer 224 can be 4 to 10. Thus, the appropriate number of first and second piezoelectric functional layers allows the piezoelectric device 22 to maintain an appropriate overall thickness, avoiding excessive thickness that could lead to excessive stiffness, thereby improving the dynamic performance of the piezoelectric device 22.

[0067] For example, in the first piezoelectric layer 223, the number of first piezoelectric functional layers can be 15, 18, 20, or 25, etc. In the second piezoelectric layer 224, the number of second piezoelectric functional layers can be 4, 6, 8, or 10, etc.

[0068] In some embodiments, the dimension (thickness) of each first piezoelectric functional layer along the z-axis can be from 5 micrometers (μm) to 15 μm; the dimension (thickness) of each second piezoelectric functional layer along the z-axis can be greater than or equal to 120 μm. Because the thickness of the first piezoelectric functional layer is relatively small, the spacing between adjacent first electrode layers can be reduced, thereby increasing the electric field strength. This allows for increased thrust and output displacement even when the driving voltage received by the piezoelectric device 22 is reduced, for example, from 150V to 24V. Furthermore, since the electric field direction of the second piezoelectric layer 224 is opposite to its own polarization, setting the thickness of the second piezoelectric functional layer to greater than or equal to 120 μm ensures that the depolarization voltage of the second piezoelectric layer 224 is much higher than the driving voltage (e.g., 24V in a low-voltage system), thus guaranteeing the long-term safe use of the piezoelectric device 22.

[0069] For example, the thickness of the first piezoelectric functional layer can be 5 μm, 8 μm, 10 μm, or 15 μm, etc. The thickness of the second piezoelectric functional layer can be 120 μm, 125 μm, 130 μm, or 135 μm, etc.

[0070] In summary, when the thickness of the first piezoelectric functional layer is relatively small and the thickness of the second piezoelectric functional layer is relatively large, setting the number of layers of the first piezoelectric functional layer to 15 to 25 and the number of layers of the second piezoelectric functional layer to 4 to 10 can avoid the problem of excessive stiffness caused by excessive thickness of the first piezoelectric layer 223 or the second piezoelectric layer 224, which would affect the output displacement.

[0071] In some embodiments, the material of the first piezoelectric functional layer is piezoelectric ceramic. It should be noted that the material of the first piezoelectric functional layer can also be other materials with piezoelectric effect, and this application does not limit this.

[0072] In some embodiments, the material of the second piezoelectric functional layer is piezoelectric ceramic. It should be noted that the material of the second piezoelectric functional layer can also be other materials with piezoelectric effect, and this application does not limit this.

[0073] In some embodiments, the first piezoelectric layer 223 is an integral structure. For example, the first piezoelectric layer 223 can be prepared by a multilayer co-firing method, that is, the first piezoelectric functional layer and the first electrode layer can be prepared by a co-firing method to form the first piezoelectric layer 223, thereby improving the overall strength and stability of the first piezoelectric layer 223.

[0074] In some embodiments, the second piezoelectric layer 224 is a monolithic structure. For example, the second piezoelectric layer 224 can be prepared by a multilayer co-firing method, that is, the second piezoelectric functional layer and the second electrode layer can be prepared by a co-firing method to form the second piezoelectric layer 224, thereby improving the overall strength and stability of the second piezoelectric layer 224.

[0075] In some embodiments, the first piezoelectric layer 223 and the second piezoelectric layer 224 can be connected by adhesive bonding, or they can be fixedly connected by other means, which is not limited in this application.

[0076] The overall performance of the piezoelectric actuator 02 is described below when the piezoelectric device 22 and the buffer structure 23 adopt different structures in some embodiments of this application.

[0077] Continue to refer to Figure 5A and Figure 5B In this embodiment, Figure 5A The piezoelectric bicrystalline wafer 12 is a piezoelectric bicrystalline wafer, and the length of the piezoelectric bicrystalline wafer can be 21 mm, the width can be 7.8 mm, and the thickness can be 1.0 mm. Among them, the first piezoelectric layer in the piezoelectric bicrystalline wafer has 18 layers and the thickness of the first piezoelectric functional layer is 16 μm, the second piezoelectric layer has 6 layers and the thickness of the second piezoelectric functional layer is 120 μm. Figure 5B The piezoelectric device 22 is with Figure 5A The same piezoelectric bicrystalline wafer. Figure 5A piezoelectric actuator 01 and Figure 5B The piezoelectric actuator 02 receives a drive voltage of 24V.

[0078] The material of the first buffer 231 of the buffer structure 23 is rigid polyurethane with a Shore D hardness of 75, the material of the second buffer 232 is polyurethane rubber with a Shore D hardness of 60, and the material of the third buffer 233 is nitrile rubber with a Shore D hardness of 45.

[0079] After testing, Figure 5B When the thickness of the buffer structure 23 is different (e.g., 1mm, 2mm, 3mm respectively), Figure 5B The thrust (greater than 2N) and output displacement (greater than 100μm) of the piezoelectric actuator 02 are both greater than Figure 5A The piezoelectric actuator 01 has a thrust (approximately 1.5 N) and an output displacement (less than 100 μm), and, Figure 5B The lifespan of the piezoelectric actuator 02 (greater than 100 million cycles) is far greater than Figure 5A The lifespan of the piezoelectric actuator 01 is less than 20 million cycles.

[0080] In other words, the technical solution of this embodiment can increase the thrust and displacement of the piezoelectric device 22 under a smaller driving voltage, and when the thickness of the buffer structure 23 is large, it can further increase the output displacement.

[0081] Continue to refer to Figure 5A and Figure 5B In this embodiment, Figure 5A The piezoelectric bicrystalline wafer 12 is a piezoelectric bicrystalline wafer, and the length of the piezoelectric bicrystalline wafer can be 21 mm, the width can be 7.8 mm, and the thickness can be 1.0 mm. Among them, the first piezoelectric layer in the piezoelectric bicrystalline wafer has 18 layers and the thickness of the first piezoelectric functional layer is 16 μm, the second piezoelectric layer has 6 layers and the thickness of the second piezoelectric functional layer is 120 μm. Figure 5B The piezoelectric device 22 is with Figure 5A The same piezoelectric bicrystalline wafer. Figure 5A piezoelectric actuator 01 and Figure 5B The piezoelectric actuator 02 receives a drive voltage of 24V.

[0082] The material of the first buffer 231 of the buffer structure 23 is rigid polyurethane with a Shore D hardness of 75, the material of the second buffer 232 is low crystallinity polyetheretherketone with a Shore D hardness of 55, and the material of the third buffer 233 is chloroprene rubber with a Shore D hardness of 40.

[0083] In other words, compared with the previous embodiment, the second buffer 232 and the third buffer 233 of this embodiment have lower hardness.

[0084] After testing, Figure 5B When the thickness of the buffer structure 23 is different (e.g., 1mm, 2mm, 3mm respectively), Figure 5B The thrust and output displacement of the piezoelectric actuator 02 are both further greater than Figure 5A The thrust and output displacement of the piezoelectric actuator 01, and, Figure 5B The lifespan of the piezoelectric actuator 02 is much longer than Figure 5A The lifespan of the piezoelectric actuator 01.

[0085] In other words, the technical solution of this embodiment further reduces the hardness of the buffer zone near the free region 222, thereby providing a larger deformation space for the fixed region 221, thus enabling a larger output displacement of the piezoelectric bicrystalline wafer. Thus, by using the buffer structure 23 with a hardness gradient provided in this application, piezoelectric actuators 02 with different output displacements and thrusts can be obtained by adjusting the thickness of the buffer structure 23 and the hardness of different regions, thereby further improving the adjustability of the piezoelectric actuator 02 and balancing the structural stability and dynamic performance of the piezoelectric actuator 02.

[0086] Continue to refer to Figure 5A and Figure 5B In this embodiment, Figure 5A The piezoelectric bicrystalline wafer 12 is a piezoelectric bicrystalline wafer, and the length of the piezoelectric bicrystalline wafer can be 21 mm, the width can be 7.8 mm, and the thickness can be 1.0 mm. Among them, the first piezoelectric layer in the piezoelectric bicrystalline wafer has 24 layers and the thickness of the first piezoelectric functional layer is 8 μm, the second piezoelectric layer has 6 layers and the thickness of the second piezoelectric functional layer is 120 μm. Figure 5B The piezoelectric device 22 is with Figure 5A The same piezoelectric bicrystalline wafer. Figure 5A piezoelectric actuator 01 and Figure 5B The piezoelectric actuator 02 receives a drive voltage of 24V.

[0087] The material of the first buffer 231 of the buffer structure 23 is rigid polyurethane with a Shore D hardness of 75, the material of the second buffer 232 is low crystallinity polyetheretherketone with a Shore D hardness of 55, and the material of the third buffer 233 is chloroprene rubber with a Shore D hardness of 40.

[0088] In other words, compared with the previous embodiment, the first piezoelectric layer 223 of this embodiment has more first piezoelectric functional layers and first electrode layers, and the thickness of the first piezoelectric functional layer is smaller.

[0089] After testing, Figure 5B When the thickness of the buffer structure 23 is different (e.g., 1mm, 2mm, 3mm respectively), Figure 5B The thrust and output displacement of the piezoelectric actuator 02 are both further greater than Figure 5A The thrust and output displacement of the piezoelectric actuator 01, and, Figure 5B The lifespan of the piezoelectric actuator 02 is much longer than Figure 5A The lifespan of the piezoelectric actuator 01.

[0090] Since the first electrode layer has more layers and the spacing between two adjacent first electrode layers is smaller, the field strength formed inside the first piezoelectric layer 223 is greater when it receives the driving voltage, thereby enhancing the deformation of the first piezoelectric layer 223 and thus simultaneously improving the thrust and output displacement of the piezoelectric device 22.

[0091] and Figure 5A Compared to the piezoelectric actuator 01, Figure 5B The piezoelectric actuator 02 not only improves thrust and output displacement with the same drive voltage (e.g., 24V), but also... Figure 5A When the piezoelectric actuator 01 receives a larger drive voltage (150V), Figure 5B The piezoelectric actuator 02 can still achieve Figure 5A The thrust and output displacement achieved by the piezoelectric actuator 01. Therefore, Figure 5B The piezoelectric actuator 02 can also improve the problem of discharge breakdown caused by excessive drive voltage.

[0092] The following will continue to combine Figure 4 The other structures of the piezoelectric actuator 02 will be described.

[0093] Continue to refer to Figure 4 In some embodiments, the base 21 may further include a main body 211 and a limiting part 212. For example, the main body 211 may extend along the xy plane. One end of the main body 211 along the z-axis has a first surface 21a, and the first surface 21a, the buffer structure 23, and the fixing area 221 of the piezoelectric device 22 are sequentially fixedly connected. The limiting part 212 is provided on the first surface 21a and is used to limit the piezoelectric device 22 along the x-axis (as an example of the first direction) and / or the y-axis (as an example of the third direction). Thus, during the installation process of the buffer structure 23 and the piezoelectric device 22 on the base 21, the limiting part 212 can effectively position and constrain the piezoelectric device 22, preventing it from shifting or misaligning during pasting or fixing. This ensures accurate relative positioning and good assembly consistency between the piezoelectric device 22, the buffer structure 23, and the base 21, and also simplifies the installation process and improves the assembly efficiency and reliability of the piezoelectric actuator 02.

[0094] In other embodiments, the base 21 can also be a clamp with a clamping structure, and the piezoelectric device 22 can be fixed by the clamping structure. Correspondingly, the buffer structure 23 can be located between the clamping structure and the piezoelectric device 22. Similarly, the buffer structure 23 can also alleviate the stress concentration phenomenon between the clamping structure and the piezoelectric device 22, and can also simultaneously improve the resonant frequency and output displacement of the piezoelectric actuator 02. The specific structure and function of the buffer structure 23 are the same as in the above embodiments, and will not be repeated here. It should be noted that this application does not impose any limitations on the specific structure of the base 21, and the base 21 can also be other structures.

[0095] The specific embodiments described above illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Although the description of this application is presented in conjunction with some embodiments, this does not mean that the features of this application are limited to this embodiment. On the contrary, the purpose of describing the application in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of this application. This application may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this application, some specific details have been omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0096] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "outer", "inner", "circumferential", "radial", "axial", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0097] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "fit" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0098] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A piezoelectric actuator, characterized in that, It includes a base (21), a piezoelectric device (22), and a buffer structure (23); among which, The piezoelectric device (22) includes a fixed region (221) and a free region (222) connected along a first direction; Along the second direction, the seat (21), the buffer structure (23), and the fixed area (221) are fixedly connected in sequence. Along the first direction, the free area (222) protrudes from the seat (21) and the buffer structure (23). The second direction intersects with the first direction. The buffer structure (23) has a lower hardness than the seat (21). The buffer structure (23) includes a first buffer (231) and a second buffer (232) connected sequentially along the first direction. Along the first direction, the first buffer (231) is further away from the free area (222) than the second buffer (232). The hardness of the first buffer (231) is greater than the hardness of the second buffer (232).

2. The piezoelectric actuator according to claim 1, characterized in that, The buffer structure (23) further includes a third buffer (233). Along the first direction, the first buffer (231), the second buffer (232), and the third buffer (233) are connected in sequence, and the hardness of the first buffer (231), the second buffer (232), and the third buffer (233) decreases in sequence.

3. The piezoelectric actuator according to claim 1 or 2, characterized in that, The piezoelectric device (22) includes a first piezoelectric layer (223) and a second piezoelectric layer (224) stacked together along the second direction, and the second piezoelectric layer (224) is stacked together with the buffer structure (23) along the second direction; The first piezoelectric layer (223) includes at least one first piezoelectric functional layer and at least one first electrode layer alternately stacked along the second direction, and the second piezoelectric layer (224) includes at least one second piezoelectric functional layer and at least one second electrode layer alternately stacked along the second direction. In the first piezoelectric layer (223), the number of layers of the first piezoelectric functional layer is 15 to 25; and / or, in the second piezoelectric layer (224), the number of layers of the second piezoelectric functional layer is 4 to 10.

4. The piezoelectric actuator according to claim 3, characterized in that, The dimensions of each of the first piezoelectric functional layers along the second direction are 5 μm to 15 μm; Each of the second piezoelectric functional layers has a dimension greater than or equal to 120 μm along the second direction, and the second piezoelectric layer (224) is used to receive a driving voltage opposite to the polarization direction of the second piezoelectric functional layer.

5. The piezoelectric actuator according to claim 4, characterized in that, The material of the first piezoelectric functional layer is piezoelectric ceramic.

6. The piezoelectric actuator according to claim 4, characterized in that, The material of the second piezoelectric functional layer is piezoelectric ceramic.

7. The piezoelectric actuator according to claim 4, characterized in that, The first piezoelectric layer (223) is an integral structure.

8. The piezoelectric actuator according to claim 4, characterized in that, The second piezoelectric layer (224) is an integral structure.

9. The piezoelectric actuator according to claim 1 or 2, characterized in that, The piezoelectric device (22) includes a piezoelectric bicrystalline wafer, the first direction being the length direction of the piezoelectric bicrystalline wafer, and the second direction being the thickness direction of the piezoelectric bicrystalline wafer.

10. The piezoelectric actuator according to claim 1 or 2, characterized in that, The Shore hardness of the buffer structure (23) is 40 to 75.

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