Piezoelectric vibration sensor and design method thereof

Abstract

The invention discloses a piezoelectric vibration sensor and a design method thereof, and relates to the field of vibration sensors, the piezoelectric vibration sensor comprises a connecting column with high temperature resistance and piezoelectric sensing units, the piezoelectric sensing units are symmetrically arranged on the two sides of the connecting column, and each piezoelectric sensing unit comprises a piezoelectric sensing element, an electrode plate and a balancing weight which have high temperature resistance, piezoelectric sensing elements are arranged on the two sides of the electrode plate, the piezoelectric sensing element on one side is arranged close to the connecting column, the piezoelectric sensing element on the other side is arranged close to the balancing weight, and a pre-tightening screw penetrates through the piezoelectric sensing elements on the two sides and the connecting column to be connected with a pre-tightening nut; the pre-tightening force change generated by different thermal expansion coefficients of each component at high temperature is reduced, so that the temperature drift is reduced, the temperature stability is improved, and the reliability and the detection accuracy are further improved; the sensor is good in comprehensive performance, stable signal output can be guaranteed when the sensor works under the high-temperature condition, the risk of material damage under the high-temperature environment is reduced, and commercialized production and application are facilitated.

Description

Technical Field

[0001] The present invention relates to the field of vibration sensors, and in particular to a piezoelectric vibration sensor and a design method thereof. Background Art

[0002] In recent years, with the rapid development of high-tech and industries such as aerospace, nuclear power, automobile, and chemical industries, people's requirements for vibration testing have also increased. The measurement equipment used in these industries usually faces extremely harsh working environments. For example, high-temperature resistant piezoelectric vibration sensors used in aerospace engine measurements need to face extreme high temperatures, high pressures, oil pollution, impact and other harsh conditions when the engine is working. This puts high demands on the stability, sensitivity, reliability and other performance of the sensor.

[0003] In the piezoelectric vibration sensors currently known to the applicant, since insulating materials need to be provided, the preload force generated by the different thermal expansion coefficients of the components at high temperatures varies greatly, the temperature drift increases, the temperature stability is low, and the reliability and detection accuracy are also reduced.

[0004] Therefore, people are in urgent need of a piezoelectric vibration sensor that is resistant to high temperatures, has good temperature stability, high reliability, and high detection accuracy. Summary of the invention

[0005] The purpose of the present invention is to provide a piezoelectric vibration sensor and a design method thereof to solve the problems existing in the above-mentioned prior art. By designing the structure and eliminating the insulating material, the temperature stability, reliability and detection accuracy are improved on the basis of high temperature resistance.

[0006] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a piezoelectric vibration sensor, comprising a connecting column with high temperature resistance and a piezoelectric sensing unit, the piezoelectric sensing units are symmetrically arranged on both sides of the connecting column, the piezoelectric sensing unit comprises a piezoelectric sensitive element, an electrode sheet and a counterweight block, all of which have high temperature resistance, the piezoelectric sensitive elements are arranged on both sides of the electrode sheet, the piezoelectric sensitive element on one side is arranged close to the connecting column, and the piezoelectric sensitive element on the other side is arranged close to the counterweight block, the pre-tightening screw passes through the piezoelectric sensing units and the connecting column on both sides and is connected with the pre-tightening nut, the piezoelectric sensitive element, the electrode sheet and the counterweight block of the piezoelectric sensing unit are all provided with through holes in the middle, and the inner peripheral wall of the through hole is spaced apart from the pre-tightening screw.

[0007] Preferably, the piezoelectric sensitive element is a YCOB piezoelectric single crystal.

[0008] Preferably, the materials of the connecting column, the counterweight block, the electrode sheet, the pre-tightening screw and the pre-tightening nut are all high-entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy.

[0009] Preferably, the piezoelectric vibration sensor further comprises a base and a shell, the connecting column is arranged on the base, the shell sealing buckle is arranged on the base, and the connecting column and the piezoelectric sensing unit are both arranged in the shell.

[0010] Preferably, the shell and the base are both made of high entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy.

[0011] Preferably, the outer peripheral edge of the base is arranged in a stepped shape, and the bottom edge of the shell matches the outer peripheral edge of the base.

[0012] Preferably, the housing is provided with a lead-out hole, the electrode sheet is connected to a wire, and the wire passes through the lead-out hole to be connected to an external device.

[0013] Preferably, the material of the wire is platinum, high entropy alloy, nickel-based high-temperature alloy or nickel.

[0014] Preferably, a mounting threaded hole for fixing the base is provided at the bottom of the base.

[0015] The present invention also provides a design method for the above-mentioned piezoelectric vibration sensor, comprising the following steps:

[0016] S1. Design the dimensions of each component of the piezoelectric vibration sensor according to the frequency response range and sensitivity requirements, and select appropriate high temperature resistant materials to process each component according to the designed dimensions;

[0017] S2, growing a YCOB single crystal by the Czochralski method, and preparing a piezoelectric single crystal of a required size as a piezoelectric sensitive element according to the required cutting shape;

[0018] S3, assemble the piezoelectric vibration sensor and complete the positioning and pre-tightening of the built-in circuit;

[0019] S4. Fix the piezoelectric vibration sensor to the test platform for calibration.

[0020] Compared with the prior art, the present invention mainly achieves the following technical effects:

[0021] This sensor does not use insulating materials, uses fewer components, and has a simpler structure. The change in preload force caused by different thermal expansion coefficients of various components under high temperature is reduced, thereby reducing temperature drift, improving temperature stability, and further improving reliability and detection accuracy. At the same time, the cooperation of the locking screw and the locking nut reduces the lateral sensitivity, improves the main performance of the sensor, and makes the sensor have higher reliability and detection accuracy. This sensor has good comprehensive performance, can ensure stable signal output when working under high temperature conditions, reduces the risk of material damage in high temperature environments, and is conducive to commercial production and application.

[0022] Compared with the prior art, other solutions of the present invention have achieved the following technical effects:

[0023] High entropy alloys have extremely high operating temperatures (above 1000°C), high strength, and good corrosion and oxidation resistance, making them suitable for applications in extreme environments. The sensitive element uses YCOB piezoelectric single crystals, which still have a very high resistivity at extremely high temperatures and can output stable electrical signals, which is beneficial for high-temperature applications. The two as core materials can increase the maximum operating temperature of the sensor to above 850°C, meeting the testing requirements under extreme conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of the structure of a piezoelectric vibration sensor in an embodiment of the present invention;

[0026] Figure 2 is a top view of a piezoelectric vibration sensor according to an embodiment of the present invention;

[0027] Figure 3 A bottom view of a piezoelectric vibration sensor according to an embodiment of the present invention;

[0028] Figure 4 is a cross-sectional view of a piezoelectric vibration sensor according to an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of the piezoelectric vibration sensor after the housing is hidden in an embodiment of the present invention;

[0030] Figure 6 It is a front view of the piezoelectric vibration sensor after the housing is hidden in the embodiment of the present invention;

[0031] Figure 7 It is a left side view of the piezoelectric vibration sensor after the housing is hidden in the embodiment of the present invention;

[0032] Figure 8 A top view of the piezoelectric vibration sensor after the housing is hidden in the embodiment of the present invention;

[0033] Among them, 1. base; 2. shell; 3. lead-out hole; 4. connecting column; 5. piezoelectric sensitive element; 6. electrode sheet; 7. counterweight; 8. pre-tightening screw; 9. pre-tightening nut; 10. mounting threaded hole. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide a piezoelectric vibration sensor and a design method thereof to solve the problems existing in the prior art. By designing the structure and eliminating the insulating material, the temperature stability, reliability and accuracy are improved on the basis of high temperature resistance.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Please refer to Figures 1 to 8 As shown, a piezoelectric vibration sensor is provided, including a connecting column 4 with high temperature resistance and a piezoelectric sensing unit. The piezoelectric sensing units are symmetrically arranged on both sides of the connecting column 4. The piezoelectric sensing unit includes a piezoelectric sensitive element 5, an electrode sheet 6 and a counterweight block 7, all of which have high temperature resistance. Piezoelectric sensitive elements 5 are arranged on both sides of the electrode sheet 6. The piezoelectric sensitive element 5 on one side is arranged close to the connecting column 4, and the piezoelectric sensitive element 5 on the other side is arranged close to the counterweight block 7. The pre-tightening screw 8 passes through the piezoelectric sensing units on both sides and the connecting column 4 and is connected to the pre-tightening nut 9. By tightening the locking nut, the piezoelectric sensing units on both sides are positioned on the connecting column 4. The connecting column 4 and the counterweight block 7 are non-conductively arranged. The sensor does not use insulating materials, uses fewer components, and has a simpler structure. At high temperatures, the change in preload force caused by different thermal expansion coefficients of various components is reduced, thereby reducing temperature drift, improving temperature stability, and further improving reliability and detection accuracy. At the same time, the cooperation of the locking screw and the locking nut reduces the lateral sensitivity, improves the main performance of the sensor, and makes the sensor have higher reliability and detection accuracy, while ensuring good stress conditions during its vibration and reducing the risk of brittle fracture; the sensor has good comprehensive performance, can ensure stable signal output when working under high temperature conditions, reduces the risk of material damage in high temperature environments, and is conducive to commercial production and application; in addition, in actual work, the counterweights 7 on both sides act simultaneously, and can generate higher signal output at the same time, thereby making the sensor obtain higher sensitivity.

[0038] In this embodiment, the specific structure of the non-conductive setting of the connecting column 4 and the counterweight block 7 is as follows: the piezoelectric sensitive element 5 of the piezoelectric sensing unit, the electrode sheet 6 and the middle part of the counterweight block 7 are all provided with through holes, and the inner peripheral wall of the through hole is spaced apart from the pre-tightening screw 8. The through hole can be circular, square or other shapes, so as to prevent the inner peripheral wall of the through hole from contacting the pre-tightening screw 8.

[0039] The piezoelectric vibration sensor also includes a base 1 and a shell 2. The connecting column 4 is arranged on the base 1. The shell 2 is sealed and buckled on the base 1. The sealing method is welding. The connecting column 4 and the piezoelectric sensor unit are both arranged in the shell 2. The base 1 and the shell 2 realize the protection of internal devices.

[0040] In order to improve the protection effect, the space formed by the base 1 and the shell 2 can be filled with inert gas. The specific filling method is: design a gap that can be filled with inert gas into the inner cavity of the shell 2. The gap can be set separately on the shell 2 or the base 1, or the gap generated when the shell 2 and the base 1 are matched can be directly utilized. After the gap is filled with inert gas, the gap can be sealed by laser welding.

[0041] In the present application, the outer edge of the base 1 is arranged in a stepped shape, and the bottom edge of the shell 2 matches the outer edge of the base 1. The stepped arrangement can not only reduce the weight of the overall sensor, but also improve the stability of the base 1 and the shell 2 after they are matched.

[0042] The connecting column 4 can also be designed as a stepped structure to further reduce the overall weight.

[0043] The housing 2 is provided with a lead-out hole 3, the electrode sheet 6 is connected to a wire, and the wire passes through the lead-out hole 3 to be connected to an external device. A corresponding seal needs to be provided at the lead-out hole 3 to prevent leakage of the internal inert gas.

[0044] In order to facilitate the installation of the sensor, a mounting threaded hole 10 for fixing the base 1 is provided at the bottom of the base 1 in the present embodiment. In actual use, the base 1 can be directly threadedly connected to the screw on the vibration source to be measured through the mounting threaded hole 10; of course, in other embodiments, a screw can also be provided at the bottom of the base 1 and screwed into the threaded hole of the vibration source to be measured, or other connection structures that can cooperate with the vibration source to be measured can be provided.

[0045] The connecting column 4 and the base 1 can be integrally provided to improve the structural strength.

[0046] In this embodiment, the piezoelectric sensitive element 5 is a YCOB piezoelectric single crystal, which has an extremely high phase transition temperature and a relatively high high temperature resistivity, and has good high temperature performance and stability. In other embodiments, the piezoelectric sensitive unit 5 may also be made of other doped YCOB single crystals.

[0047] In this embodiment, the counterweight block 7 is made of high-entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy, has high density, elastic modulus and anti-creep properties, can maintain high stiffness and temperature stability in a high-temperature environment, and provide inertial force for the shear deformation of the piezoelectric single crystal. The mass of the counterweight block 7 is closely related to the sensitivity of the sensor. In order to ensure higher sensitivity, a high-quality, high-specific gravity counterweight block 7 is generally required. Under the condition of meeting the required resonant frequency range, a large-mass, small-volume counterweight block 7 has more obvious advantages.

[0048] The electrode sheet 6 used in this embodiment is made of high entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy precision-processed, which can stably maintain good electrical conductivity at high temperatures and ensure that the lead wire has little interference with the sensor.

[0049] The wire is made of platinum, high entropy alloy, nickel-based high-temperature alloy or nickel.

[0050] The pre-tightening screw 8 and pre-tightening nut 9 used in this embodiment are made of high-entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy through precision machining, have high strength, meet the requirements for applying the pre-tightening force, and greatly reduce the risk of brittle fracture of the screw.

[0051] The base 1 and the housing 2 used in this embodiment are made of high entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy precision-processed, have excellent high-temperature oxidation resistance and corrosion resistance, and can play a role in protecting the internal components of the sensor.

[0052] The materials used for each component have extremely high operating temperatures (above 1000°C), high strength, good corrosion resistance and oxidation resistance, and are suitable for applications in extreme environments. The piezoelectric sensitive element 5 uses YCOB piezoelectric single crystal, which still has a very high resistivity at extremely high temperatures and can output stable electrical signals, which is beneficial to high-temperature applications. The two as core materials can increase the maximum operating temperature of the sensor to above 850°C, meeting the testing requirements under extreme conditions.

[0053] The YCOB piezoelectric single crystal is provided with a high smoothness to ensure good contact between components while reducing the probability of breakage.

[0054] The basic testing principle of the piezoelectric vibration sensor is based on the piezoelectric effect of the piezoelectric sensitive element 5. The sensor is rigidly connected to the vibration source to be tested through the mounting threaded hole 10. When the vibration source vibrates, an acceleration related to its vibration will be generated. At this time, the base 1 of the sensor will also generate vibrations with the same acceleration. Due to the existence of inertia, the vibration acceleration of the sensor's counterweight 7 will be the same as that of the base 1 but in the opposite direction. At this time, the piezoelectric sensitive element 5 and the counterweight 7 will generate vibrations with the same acceleration and will be subject to the shear inertial stress applied by the counterweight 7. Due to the piezoelectric effect of the piezoelectric material, the piezoelectric sensitive element 5 will generate positive and negative charges related to the inertial force on both surfaces of the material. The wires connecting the electrode sheet 6 are led out from the lead-out port set on the housing 2, and the wires are connected to the calibration equipment to realize the conversion between the acceleration signal and the electrical signal.

[0055] In another embodiment, the present invention further provides a design method of the above-mentioned piezoelectric vibration sensor, comprising the following steps:

[0056] S1. Design the dimensions of each component of the piezoelectric vibration sensor according to the frequency response range and sensitivity requirements, select appropriate high temperature resistant materials and process each component according to the designed dimensions to ensure that the processing error is less than 0.02mm;

[0057] S2, growing a YCOB single crystal by a Czochralski method, and preparing a piezoelectric single crystal of a required size according to the required cutting shape as a piezoelectric sensitive element 5;

[0058] S3, assembling the components of the piezoelectric vibration sensor using the positioning and pre-tightening tooling, and setting the pre-tightening torque through the pre-tightening screw 8 according to the theoretical calculation results to complete the positioning and pre-tightening of the built-in circuit;

[0059] S4. Fix the piezoelectric vibration sensor to the test platform for calibration.

[0060] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0061] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0062] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A piezoelectric vibration sensor, characterized in that: It includes a connecting column with high temperature resistance and a piezoelectric sensing unit. The piezoelectric sensing units are symmetrically arranged on both sides of the connecting column. The piezoelectric sensing unit includes a piezoelectric sensitive element, an electrode sheet and a counterweight block, all of which have high temperature resistance. The piezoelectric sensitive elements are arranged on both sides of the electrode sheet, the piezoelectric sensitive element on one side is arranged close to the connecting column, and the piezoelectric sensitive element on the other side is arranged close to the counterweight block. The pre-tightening screw passes through the piezoelectric sensing units and the connecting column on both sides and is connected with the pre-tightening nut. Through holes are opened in the middle of the piezoelectric sensitive element, the electrode sheet and the counterweight block of the piezoelectric sensing unit, and the inner circumferential wall of the through hole is arranged at a distance from the pre-tightening screw.

2. The piezoelectric vibration sensor according to claim 1, characterized in that: The piezoelectric sensitive element is a YCOB piezoelectric single crystal.

3. The piezoelectric vibration sensor according to claim 1, characterized in that: The materials of the connecting column, the counterweight block, the electrode sheet, the pre-tightening screw and the pre-tightening nut are all high-entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy.

4. The piezoelectric vibration sensor according to claim 1, characterized in that: The piezoelectric vibration sensor also includes a base and a shell. The connecting column is arranged on the base. The shell seal is arranged on the base. The connecting column and the piezoelectric sensing unit are both arranged in the shell.

5. The piezoelectric vibration sensor according to claim 4, characterized in that: The shell and the base are both made of high entropy nickel-based high-temperature alloy or nickel-based high-temperature alloy.

6. The piezoelectric vibration sensor according to claim 4, characterized in that: The outer peripheral edge of the base is arranged in a stepped shape, and the bottom edge of the shell matches the outer peripheral edge of the base.

7. The piezoelectric vibration sensor according to claim 4, characterized in that: The housing is provided with a lead-out hole, the electrode sheet is connected to a wire, and the wire passes through the lead-out hole to be connected to an external device.

8. The piezoelectric vibration sensor according to claim 7, characterized in that: The material of the wire is platinum, high entropy alloy, nickel-based high-temperature alloy or nickel.

9. The piezoelectric vibration sensor according to claim 4, characterized in that: The bottom of the base is provided with a mounting threaded hole for fixing the base.

10. A method for designing a piezoelectric vibration sensor, characterized in that: The piezoelectric vibration sensor according to any one of claims 1 to 9 comprises the following steps: S1. Design the dimensions of each component of the piezoelectric vibration sensor according to the frequency response range and sensitivity requirements, and select appropriate high temperature resistant materials to process each component according to the designed dimensions; S2, growing a YCOB single crystal by the Czochralski method, and preparing a piezoelectric single crystal of a required size as a piezoelectric sensitive element according to the required cutting shape; S3, assemble the piezoelectric vibration sensor and complete the positioning and pre-tightening of the built-in circuit; S4. Fix the piezoelectric vibration sensor to the test platform for calibration.

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