Piezoelectric actuators

Abstract

The present invention provides a piezoelectric actuator. The piezoelectric actuator includes: a housing defining a housing with one end open and the other end closed; a piezoelectric component disposed in the housing, with the first end of the piezoelectric component fixed to the closed end of the housing, and the piezoelectric component configured to be deformable along its own axial direction; an output member fixed to the second end of the piezoelectric component to cause the output member to displace; a displacement detection component located in the housing, the displacement detection component including a movable member and a detection component, one end of the output member extending out of the opening, the other end of the output member being provided with a movable member, the movable member following the displacement of the output member, and the detection component being used to convert the mechanical displacement of the movable member into an electrical signal output. The technical solution of the present invention solves the problem of large actual displacement measurement errors of piezoelectric actuators in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of micro-driving technology, and in particular to a piezoelectric actuator. Background Art

[0002] Existing closed-loop piezoelectric actuators all use strain gauges as closed-loop sensors for feedback signals. Although strain gauges offer advantages such as high resolution, compact size, simple wiring, and low cost, in piezoelectric actuator applications, strain gauges do not directly measure the actuator's actual displacement output. Instead, they measure the local deformation of the piezoelectric ceramic within the actuator, and then use subsequent circuit calculations to correspond to the actuator's actual output displacement. This can result in signal errors. For example, patent application number 201310586696.6 discloses a closed-loop controlled packaged piezoelectric ceramic actuator and a method for fixing a resistance strain gauge. In the closed-loop controlled packaged piezoelectric ceramic actuator disclosed in this application, the actual displacement is characterized by strain gauges detecting local deformation. The actual test accuracy is approximately one thousandth of the total stroke, resulting in a low level of accuracy. Furthermore, strain gauges are not resistant to moisture and heat and have weak anti-interference capabilities. Closed-loop actuators with strain gauges are not suitable for use in humid and hot working conditions or those with strong electromagnetic interference. Summary of the Invention

[0003] The main purpose of the present invention is to provide a piezoelectric actuator to solve the problem of large actual displacement measurement error of the piezoelectric actuator in the prior art.

[0004] In order to achieve the above-mentioned objectives, the present invention provides a piezoelectric actuator, comprising: a housing defining a accommodating cavity with one end open and the other end closed; a piezoelectric component disposed in the accommodating cavity, with a first end of the piezoelectric component fixed to the closed end of the accommodating cavity, and the piezoelectric component configured to be able to deform along its own axial direction; an output member fixed to the second end of the piezoelectric component to cause the output member to generate displacement; a displacement detection component located in the accommodating cavity, the displacement detection component comprising a movable member and a detection component, with one end of the output member extending out of the opening, and a movable member being provided at the other end of the output member, the movable member following the displacement of the output member, and the detection component being used to convert the mechanical displacement of the movable member into an electrical signal output.

[0005] Furthermore, the movable component includes an iron core, and the detection component includes: a primary coil, which is configured to be able to pass alternating current and excite the iron core to generate a magnetic field; two secondary coils, the two secondary coils are respectively located on both sides of the primary coil along the axial direction, each secondary coil generates an induced voltage according to the movement of the iron core, and the two secondary coils are connected in anti-series to output a differential voltage.

[0006] Furthermore, the piezoelectric component is a cylindrical structure with a through hole, and part of the output component is located in the through hole; the piezoelectric actuator also includes a support tube located in the accommodating cavity, the second end of the piezoelectric component is fixed to the closed end of the accommodating cavity through the support tube, the detection component is connected to the outer periphery of the support tube, and the iron core moves in the support tube.

[0007] Furthermore, the detection component is connected to the outer periphery of the piezoelectric component. The piezoelectric component is a cylindrical structure with a through hole. Part of the output component is located in the through hole. The iron core is movably arranged in the through hole.

[0008] Furthermore, the detection component is connected to the outer periphery of the piezoelectric component, and the iron core is a hollow structure and is movably arranged on the outer periphery of the detection component.

[0009] Furthermore, the output displacement s of the output component satisfies the formula:

[0010] ;

[0011] Among them, K0, K1, K2, and K3 are coefficients determined by experimental calibration;

[0012] E out is the output differential voltage;

[0013] E0 is the excitation voltage input to the primary coil.

[0014] Furthermore, when the piezoelectric actuator further includes a support cylinder located in the accommodating cavity and the detection member is connected to the outer periphery of the support cylinder, the output displacement s of the output member satisfies the formula:

[0015] ;

[0016] Where k is the linear coefficient;

[0017] is the output differential voltage;

[0018] is the excitation voltage input to the primary coil;

[0019] b is the zero point offset coefficient.

[0020] Furthermore, an insulating layer is provided on the periphery of the piezoelectric component, and the insulating layer is located between the piezoelectric component and the detection component.

[0021] Furthermore, the output component includes: a base, located in the accommodating cavity, the base is fixed to the piezoelectric component; an output member, one end of the output member is connected to the base, and the other end of the output member extends out of the opening; a mounting member, connected to the side of the base away from the output member, and a movable member is provided on the mounting member.

[0022] Furthermore, when the piezoelectric component is a cylindrical structure, the mounting piece is a columnar structure and is at least partially disposed inside the piezoelectric component; or, when the piezoelectric component is a columnar structure, at least part of the mounting piece is located on the outer periphery of the piezoelectric component.

[0023] Furthermore, the piezoelectric actuator also includes an elastic member, which is located on the side of the output member facing away from the piezoelectric component, one end of the elastic member abuts against the top wall of the accommodating cavity near the opening, and the other end of the elastic member abuts against the output member; or, an adhesive layer is provided on the second end of the piezoelectric component, and the output member is fixed to the piezoelectric component through the adhesive layer.

[0024] By applying the technical solution of the present invention, compared with the problem of large detection error caused by using strain gauges to detect local deformation to characterize the actual output displacement in the prior art, in the present invention, the piezoelectric component can produce a certain deformation along the axial direction. Since the first end of the piezoelectric component is fixed at the closed end of the accommodating cavity, the second end of the piezoelectric component causes the output member to produce displacement, and when the output member is displaced, it will drive the movable member to move together. In this way, the displacement produced by the movable member is the actual output displacement of the output member, that is, the displacement of the movable member is the total deformation of the piezoelectric component. When the movable member is displaced, the detection member will produce an electrical signal change. By calculating the electrical signal change generated by the detection member, the displacement produced by the movable member can be obtained to obtain the actual output displacement produced by the output member, thereby avoiding using the local deformation detected by the strain gauge to characterize the actual output displacement of the output member, thereby solving the problem of inaccurate detection of the actual output displacement by the piezoelectric actuator in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 FIG2 shows a schematic structural diagram of a first embodiment of a piezoelectric actuator of the present invention;

[0027] Figure 2 FIG2 shows a structural diagram of a second embodiment of a piezoelectric actuator of the present invention;

[0028] Figure 3 FIG2 shows a schematic structural diagram of a third embodiment of a piezoelectric actuator of the present invention;

[0029] Figure 4 A circuit diagram showing a detection component of a piezoelectric actuator of the present invention;

[0030] Figure 5 The figure shows the assembly flow chart of the second embodiment and the third embodiment of the piezoelectric actuator of the present invention.

[0031] The above drawings include the following reference numerals:

[0032] 10. Housing; 20. Piezoelectric component; 30. Output member; 31. Base; 32. Output member; 33. Mounting member; 51. Movable member; 52. Detection member; 521. Primary coil; 522. Secondary coil; 53. Support tube; 55. Elastic member. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by those familiar with this technology. They are not used to limit the conditions for implementation of the present invention and therefore have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0035] like Figures 1 to 4 As shown, the present invention provides a piezoelectric actuator, including: a housing 10, which defines a receiving cavity with one end open and the other end closed; a piezoelectric component 20, which is arranged in the receiving cavity, and the first end of the piezoelectric component 20 is fixed to the closed end of the receiving cavity, and the piezoelectric component 20 is configured to be able to deform along its own axial direction; an output member 30, which is fixed to the second end of the piezoelectric component 20 to cause the output member 30 to be displaced; a displacement detection component, which is located in the receiving cavity, and the displacement detection component includes a movable member 51 and a detection component 52, one end of the output member 30 extends out of the opening, and the other end of the output member 30 is provided with a movable member 51, the movable member 51 follows the displacement of the output member 30, and the detection component 52 is used to convert the mechanical displacement of the movable member 51 into an electrical signal output.

[0036] In the above technical solution, compared with the problem of large detection error caused by using strain gauges to detect local deformation to represent the actual output displacement in the prior art, in the present invention, the piezoelectric component 20 can produce a certain deformation along the axial direction. Since the first end of the piezoelectric component 20 is fixed to the closed end of the accommodating cavity, the second end of the piezoelectric component 20 causes the output member 30 to displace, and when the output member 30 is displaced, it will drive the movable member 51 to move together. In this way, the displacement generated by the movable member 51 is the actual output displacement of the output member 30, that is, the displacement of the movable member 51 is the total deformation of the piezoelectric component 20. When the movable member 51 is displaced, the detection member 52 will generate an electrical signal change. By calculating the electrical signal change generated by the detection member 52, the displacement generated by the movable member 51 can be obtained to obtain the actual output displacement generated by the output member 30, thereby avoiding using the local deformation detected by the strain gauge to represent the actual output displacement of the output member 30, thereby solving the problem of inaccurate detection of the actual output displacement by the piezoelectric actuator in the prior art.

[0037] Furthermore, the coordination between the movable component 51 and the detection component 52 is less affected by the environment than the strain gauge.

[0038] Specifically, in the embodiment of the present invention, the output member 30 is a rigid transmission structure. Thus, during the movement, the output member 30 will not deform, thereby avoiding affecting the detection accuracy of the actual output displacement of the piezoelectric actuator.

[0039] Specifically, in an embodiment of the present invention, the piezoelectric component 20 is a multilayer piezoelectric ceramic, such as: barium titanate-based lead-free piezoelectric ceramic, bismuth-containing perovskite piezoelectric ceramic, etc.; thus, when the multilayer piezoelectric ceramic is energized, due to the inverse piezoelectric effect of the piezoelectric material, the multilayer piezoelectric ceramic will be able to produce a certain deformation along the axial direction.

[0040] Specifically, in the embodiment of the present invention, the output member 30 is fixedly connected to the movable member 51 . Preferably, the output member 30 is fixedly connected to the movable member 51 by glue.

[0041] like Figures 1 to 4 As shown, in an embodiment of the present invention, the movable component 51 includes an iron core, and the detection component 52 includes: a primary coil 521, which is configured to be able to pass alternating current and excite the iron core to generate a magnetic field; two secondary coils 522, and the two secondary coils 522 are respectively located on both sides of the primary coil 521 along the axial direction, each secondary coil 522 generates an induced voltage according to the movement of the iron core, and the two secondary coils 522 are connected in anti-series to output a differential voltage.

[0042] In the above technical solution, the primary coil 521 generates a magnetic field after being energized. When the iron core in the through hole of the primary coil 521 is displaced in the magnetic field generated by the closed circuit, the magnetic field of the closed circuit will change. According to the electromagnetic field theory, an electric field will be generated around the changing magnetic field. The electric field causes the free electrons in the two secondary coils 522 to move in a directional manner to form a current. The two secondary coils 522 can respectively generate induced potentials. Since the two secondary coils 522 are connected in anti-series, the detection component 52 can output the differential voltage of the two secondary coils 522. According to the principle of the linear variable differential transformer, there is a linear relationship between the displacement of the iron core and the differential voltage. Therefore, the actual displacement output of the piezoelectric actuator is obtained by analyzing and calculating the differential voltage signal. In this way, compared with the large error caused by local detection of the strain gauge, the detection accuracy can be improved by setting the detection component 52 to detect the displacement of the movable component 51.

[0043] It should be noted that, in the embodiment of the present invention, the detection component 52 and the movable component 51 form a linear variable differential transformer (LVDT). By setting up the LVDT, a linear relationship between the iron core and the differential voltage can be obtained.

[0044] Specifically, in the embodiment of the present invention, the two secondary coils 522 are connected in anti-series and have the same winding method. In this way, the same winding method can prevent the two secondary coils 522 from affecting each other during electromagnetic induction.

[0045] It should be noted that, in the embodiments of the present invention, Figure 4 E1 and E2 are the output voltages of the two secondary coils respectively.

[0046] like Figures 1 to 3 As shown, in an embodiment of the present invention, the output member 30 includes: a base 31, located in the accommodating cavity, the base 31 is fixed to the piezoelectric component 20; an output member 32, one end of the output member 32 is connected to the base 31, and the other end of the output member 32 extends out of the opening; a mounting member 33, connected to the side of the base 31 away from the output member 32, and a movable member 51 is provided on the mounting member 33.

[0047] Through the above-mentioned arrangement, when the piezoelectric component 20 is energized and deformed, the base 31 can simultaneously generate displacement, and the base 31 can drive the output member 32 and the mounting member 33 to move simultaneously. In this way, on the one hand, the normal operation of the piezoelectric actuator, that is, the output displacement, can be achieved. On the other hand, the mounting member 33 can drive the movable component 51 to move, thereby causing the detection component 52 to generate an electrical signal change, and then the output displacement of the movable component 51, that is, the actual output displacement of the output member 32, can be calculated.

[0048] Preferably, in the embodiment of the present invention, the base 31 , the output member 32 and the mounting member 33 are an integrally formed structure.

[0049] Specifically, in the embodiment of the present invention, the output member 32 may be in various shapes such as a ball head, a flat head, an internal thread, an external thread, etc.

[0050] like Figures 1 to 3 In an embodiment of the present invention, the piezoelectric actuator further includes an elastic member 55, which is located on a side of the output member 30 facing away from the piezoelectric assembly 20. One end of the elastic member 55 abuts against the top wall of the accommodating cavity near the opening, and the other end of the elastic member 55 abuts against the output member 30. In this way, the elastic member 55 can press the output member 30 against the piezoelectric assembly 20, thereby enabling the output member 30 to move continuously during the deformation of the piezoelectric assembly 20.

[0051] Preferably, in the embodiment of the present invention, one end of the elastic member 55 abuts against the top wall of the accommodating cavity close to the opening, and the other end of the elastic member 55 abuts against a side of the base 31 close to the output member 32 .

[0052] Preferably, in the embodiment of the present invention, the elastic member 55 is a spring.

[0053] like Figures 1 to 3 As shown in the embodiment of the present invention, an adhesive layer is provided on the second end of the piezoelectric assembly 20, and the output member 30 is fixed to the piezoelectric assembly 20 via the adhesive layer. This can enhance the secure connection between the output member 30 and the piezoelectric assembly 20, thereby preventing the output member 30 and the piezoelectric assembly 20 from becoming misaligned due to external forces, thereby preventing the piezoelectric assembly 20 from being unable to move the output member 30 together when it deforms.

[0054] Preferably, in the embodiment of the present invention, the bonding layer between the piezoelectric component 20 and the output member 30 is formed of an adhesive, such as glue, but the constituent material of the bonding layer includes but is not limited to glue.

[0055] Example 1

[0056] like Figure 1 As shown, in embodiment 1 of the present invention, the piezoelectric component 20 is a tubular structure having a through hole, and part of the output member 30 is located in the through hole; the piezoelectric actuator also includes a support tube 53 located in the accommodating cavity, the second end of the piezoelectric component 20 is fixed to the closed end of the accommodating cavity through the support tube 53, the detection member 52 is connected to the outer periphery of the support tube 53, and the iron core moves in the support tube 53.

[0057] Through the above-mentioned arrangement, on the one hand, compared with the problem in the prior art that the strain gauge is directly arranged on the measuring substrate, which causes a large detection error, in the first embodiment of the present invention, the detection member 52 is fixed to the support tube 53, which can avoid directly fixing the detection member 52 to the piezoelectric component 20, thereby avoiding the problem that the deformation of the piezoelectric component 20 affects the detection accuracy of the detection member 52; on the other hand, by setting the piezoelectric component 20 as a tubular structure with a through hole, space can be reserved for the installation and movement of the output member 30 and the iron core.

[0058] It should be noted that in the first embodiment of the present invention, when the piezoelectric actuator further includes a support cylinder 53 located in the accommodating cavity and the detection member 52 is connected to the outer periphery of the support cylinder 53, since the detection member 52 is not in direct contact with the piezoelectric assembly, the output displacement s of the output member 30 satisfies the formula:

[0059] ;

[0060] Where k is the linear coefficient;

[0061] E out is the output differential voltage;

[0062] E0 is the excitation voltage input to the primary coil;

[0063] b is the zero point offset coefficient.

[0064] In the above technical solution, by substituting the excitation voltage of the primary coil 521, the differential voltage of the secondary coil 522 and the related coefficients into the formula, the output displacement s of the output component 30 can be obtained, that is, the actual displacement output of the piezoelectric actuator can be obtained, so as to avoid the problem of large displacement detection errors caused by using strain gauges to perform local detection of the deformation of the piezoelectric ceramic.

[0065] The measurement method in which the strain gauge is adhered to the measuring substrate with an adhesive is to specifically measure the deformation of the substrate in the area where the strain gauge is attached, and then convert the deformation of the substrate according to the ratio of the length of the strain gauge area to the length of the entire substrate. Since the substrate and the strain gauge are mostly bonded together by glue, after the substrate is deformed, the glue layer will deform first, and then the strain gauge will participate in the measurement, so it will inevitably produce mechanical lag with the displacement or deformation of the substrate; in the first embodiment of the present invention, the detection component 52 directly measures the displacement of the movable component 51, so the measurement accuracy is higher.

[0066] Specifically, in the first embodiment of the present invention, support tube 53 is a coil bobbin constructed from a highly rigid material, including but not limited to steel, ceramic, or glass. This reduces the amount of actuator output displacement that would otherwise be lost due to compression of the coil bobbin under load, thereby avoiding displacement detection errors.

[0067] like Figure 1 As shown, in the first embodiment of the present invention, when the piezoelectric assembly 20 is a cylindrical structure, the mounting member 33 is a columnar structure and is at least partially disposed within the piezoelectric assembly 20. This allows for installation and movement of the mounting member 33 and the iron core fixedly connected to the mounting member 33, thereby saving the overall space of the piezoelectric actuator.

[0068] Example 2

[0069] like Figure 2 As shown, the difference between the second embodiment of the present invention and the first embodiment is that the piezoelectric component 20 replaces the support tube 53 as the coil skeleton of the detection member 52. The detection member 52 is connected to the outer periphery of the piezoelectric component 20. The piezoelectric component 20 is a cylindrical structure with a through hole. Part of the output member 30 is located in the through hole. The iron core is movably arranged in the through hole.

[0070] In the above technical solution, by replacing the support tube 53 with the piezoelectric component 20 as the coil skeleton of the detection component 52, the axial space of the piezoelectric actuator can be fully utilized, and a piezoelectric actuator with a smaller axial size can be obtained.

[0071] Specifically, in the second embodiment of the present invention, an insulating layer is provided on the periphery of the piezoelectric assembly 20, and the insulating layer is located between the piezoelectric assembly 20 and the detection member 52. This prevents the current generated by the detection member 52 from interfering with the deformation of the piezoelectric assembly 20, thereby preventing the normal operation of the piezoelectric actuator from being affected.

[0072] Specifically, in the second embodiment of the present invention, the surface of the piezoelectric component 20 is coated with a flexible insulating material, and the coating thickness must meet the breakdown voltage greater than or equal to 6 times the operating voltage. The flexible insulating material includes but is not limited to Teflon and encapsulation paint.

[0073] It should be noted that if Figure 5 In the second embodiment of the present invention, after the piezoelectric component 20 is insulated and packaged, a primary coil 521 and two secondary coils 522 located on either side of the primary coil 521 are wound in a designated area of the piezoelectric component 20. After the coils are wound, the output member 30 and the iron core are assembled. After the above components are fixed, the primary coil 521 and the piezoelectric component 20 are energized in sequence, and the voltage output of the secondary coil 522 is tested to confirm that the iron core and the detection member 52 system are normal. The elastic member 55 is then integrated with the housing 10 to obtain a complete piezoelectric actuator.

[0074] It should be noted that, in the second embodiment of the present invention, since the piezoelectric component 20 will have axial deformation during operation, in this embodiment, the detection member 52 is arranged on the periphery of the piezoelectric component 20. The axial deformation of the piezoelectric component 20 directly causes the position and size of the detection member 52 to change, thereby causing the output differential voltage E to change.out The relationship between the output displacement and the magnetic field intensity of the magnetic field system composed of the detection member 52 and the iron core varies slightly with the displacement of the piezoelectric component 20. Therefore, in the second embodiment of the present invention, through a large number of experiments and data fitting, a relationship formula between the coefficients K2 and K3, the iron core displacement and the differential voltage can be obtained, so that the output displacement of the iron core can be calculated more accurately, and the actual displacement output of the piezoelectric actuator can be obtained more accurately. Specifically, the output displacement s of the output member 30 satisfies the formula:

[0075] ;

[0076] Among them, K0, K1, K2, and K3 are coefficients determined by experimental calibration;

[0077] E out is the output differential voltage;

[0078] E0 is the excitation voltage input to the primary coil.

[0079] In the above technical solution, by substituting the excitation voltage of the primary coil 521, the differential voltage of the secondary coil 522 and the related coefficients into the formula, the output displacement s of the output component 30 can be obtained, that is, the actual displacement output of the piezoelectric actuator can be obtained, so as to avoid the problem of large displacement detection errors caused by using strain gauges to perform local detection of the deformation of the piezoelectric ceramic.

[0080] It should be noted that when coefficients K2 and K3 are 0, the formula becomes a linear formula, and K0 is the zero-point offset coefficient b. As a special case formula, it also satisfies the output displacement s formula in Example 1. The other structures in this Example 2 are the same as those in Example 1 and will not be repeated here.

[0081] Example 3

[0082] like Figure 3 The third embodiment of the present invention differs from the second embodiment in that the detection member 52 is connected to the outer periphery of the piezoelectric assembly 20, and the iron core is a hollow structure and is movably disposed on the outer periphery of the detection member 52. This can reduce the manufacturing cost of the piezoelectric assembly 20 and save axial space for the piezoelectric actuator.

[0083] Specifically, in the third embodiment of the present invention, the piezoelectric component 20 is a non-hollow cylindrical ceramic stack. Compared with a ceramic stack with a cylindrical structure having through holes, the non-hollow cylindrical ceramic stack has a lower manufacturing cost.

[0084] like Figure 3As shown in the third embodiment of the present invention, when the piezoelectric assembly 20 is a columnar structure, at least part of the mounting member 33 is located on the outer periphery of the piezoelectric assembly 20. In this way, space can be reserved on the outer periphery of the piezoelectric assembly 20 for the mounting member 33 and the iron core fixedly connected to the mounting member 33 to be installed and moved, thereby saving the overall space of the piezoelectric actuator.

[0085] Specifically, in the third embodiment of the present invention, the mounting member 33 is a cylindrical structure, or the mounting member 33 includes two connecting rods.

[0086] Specifically, in the third embodiment of the present invention, the iron core is a cylindrical structure, or the iron core includes two connecting rods.

[0087] The other structures in this embodiment 3 are the same as those in the embodiment 2 and will not be described again here.

[0088] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: compared with the problem of large detection error caused by using strain gauges to detect local deformation to characterize the actual output displacement in the prior art, in the present invention, the piezoelectric component can produce a certain deformation along the axial direction. Since the first end of the piezoelectric component is fixed at the closed end of the accommodating cavity, the second end of the piezoelectric component causes the output member to produce displacement, and when the output member is displaced, it will drive the movable member to move together. In this way, the displacement generated by the movable member is the actual output displacement of the output member, that is, the displacement of the movable member is the total deformation of the piezoelectric component. When the movable member is displaced, the detection member will generate an electrical signal change. By calculating the electrical signal change generated by the detection member, the displacement generated by the movable member can be obtained to obtain the actual output displacement generated by the output member, thereby avoiding using the local deformation detected by the strain gauge to characterize the actual output displacement of the output member, thereby solving the problem of inaccurate detection of the actual output displacement by the piezoelectric actuator in the prior art.

[0089] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A piezoelectric actuator, characterized in that: include: The housing (10) defines a receiving cavity with one end open and the other end closed; A piezoelectric component (20) is disposed in the accommodating cavity, a first end of the piezoelectric component (20) is fixed to a closed end of the accommodating cavity, and the piezoelectric component (20) is configured to be deformable along its own axial direction; an output member (30) fixed to the second end of the piezoelectric component (20) so as to cause the output member (30) to generate displacement; A displacement detection component is located in the accommodating cavity, the displacement detection component includes a movable member (51) and a detection member (52), one end of the output member (30) extends out of the opening, the other end of the output member (30) is provided with the movable member (51), the movable member (51) follows the displacement of the output member (30), and the detection member (52) is used to convert the mechanical displacement of the movable member (51) into an electrical signal output; The movable member (51) includes an iron core, and the detection member (52) includes: A primary coil (521) is configured to be capable of passing alternating current and exciting the iron core to generate a magnetic field; Two secondary coils (522), the two secondary coils (522) are respectively located on both sides of the primary coil (521) along the axial direction, each secondary coil (522) generates an induced voltage according to the movement of the iron core, and the two secondary coils (522) are connected in anti-series to output a differential voltage, and the two secondary coils (522) are wound in the same manner; The output displacement s of the output member (30) satisfies the formula: Among them, K0, K1, K2, and K3 are coefficients determined by experimental calibration; E out is the output differential voltage; E0 is the excitation voltage input to the primary coil; The detection member (52) is connected to the outer periphery of the piezoelectric component (20), the piezoelectric component (20) is a cylindrical structure with a through hole, part of the output member (30) is located in the through hole, and the iron core is movably arranged in the through hole; or, The detection component (52) is connected to the outer periphery of the piezoelectric component (20), and the iron core is a hollow structure and is movably arranged on the outer periphery of the detection component (52); An insulating layer is provided on the periphery of the piezoelectric component (20), and the insulating layer is located between the piezoelectric component (20) and the detection component (52); The surface of the piezoelectric component (20) is coated with a flexible insulating material, and the coating thickness must satisfy a breakdown voltage greater than or equal to 6 times the operating voltage; and the output member (30) is a rigid transmission structure.

2. The piezoelectric actuator according to claim 1, wherein The output member (30) comprises: A base (31) is located in the accommodating cavity, and the base (31) is fixed to the piezoelectric component (20); an output member (32), one end of the output member (32) being connected to the base (31), and the other end of the output member (32) extending out of the opening; The mounting member (33) is connected to a side of the base (31) facing away from the output member (32), and the movable component (51) is provided on the mounting member (33).

3. The piezoelectric actuator according to claim 2, wherein: When the piezoelectric component (20) is a cylindrical structure, the mounting member (33) is a columnar structure and is at least partially disposed within the piezoelectric component (20); or, When the piezoelectric component (20) is a columnar structure, at least part of the mounting member (33) is located on the outer peripheral side of the piezoelectric component (20).

4. The piezoelectric actuator according to claim 1, wherein: The piezoelectric actuator further comprises an elastic member (55), the elastic member (55) being located on a side of the output member (30) facing away from the piezoelectric assembly (20), one end of the elastic member (55) being in contact with a top wall of the accommodating cavity close to the opening, and the other end of the elastic member (55) being in contact with the output member (30); or, An adhesive layer is provided on the second end of the piezoelectric component (20), and the output member (30) is fixed to the piezoelectric component (20) via the adhesive layer.

Images