Shear type high-temperature piezoelectric acceleration sensor structure

Abstract

The utility model discloses a shearing type high-temperature piezoelectric acceleration sensor structure, which comprises a base, a central column arranged on the base, and a wedge-shaped pre-tightening block, a piezoelectric plate group, a mass block and a square shell which are sequentially arranged outside the central column from inside to outside, the piezoelectric plate group is sleeved outside the central column, a gap is formed between the piezoelectric plate group and the central column, the mass block is sleeved on the outer surface of the piezoelectric plate group, the square shell is sleeved on the outer surface of the mass block, the outer surface of the central column is processed into a slope surface smaller than 90 degrees, and the wedge-shaped pre-tightening block is inserted in the gap between the piezoelectric plate group and the central column. The inner surface of the wedge-shaped pre-tightening block is in interference fit with the slope surface of the outer surface of the center column, the center column is in threaded connection with a bolt, and the wedge-shaped pre-tightening block is pressed downwards through the bolt. The device is simple in structure and simple and convenient to assemble; and the sensor can be used for vibration monitoring in a high-temperature environment of 200 DEG C, and has relatively stable sensitivity.

Description

Technical Field

[0001] The utility model relates to the technical field of piezoelectric acceleration sensors, in particular to a shear-type high-temperature piezoelectric acceleration sensor structure. Background Art

[0002] At present, there are two main types of piezoelectric accelerometers: compression type and shear type. The compression type piezoelectric accelerometer has a simple structure and high frequency response. However, its sensitive element is directly mounted on the sensor base. Due to the surface-to-surface contact, noise, base strain and other interference signals have a strong impact on it. In addition, the direction of the bolt preload is consistent with the direction of the acceleration to be measured, and the preload nut that fastens the piezoelectric sheet and the mass block is prone to loosening. The shear type piezoelectric accelerometer is more sensitive than the compression type sensor, and its sensitive element is separated from the base, which can effectively isolate the base strain. The interference signal of the base has less impact on it, the test accuracy is higher, and the interference sensitivity is much smaller than that of the compression type sensor.

[0003] High-temperature piezoelectric accelerometers are mainly used in the fields of aviation, aerospace, weapons, nuclear power, automotive electronics, etc. to perform vibration and impact testing, fault diagnosis and monitoring of key components. In order to ensure the authenticity and accuracy of the test data, the sensor needs to be as close as possible to the high-temperature working area (such as the nozzle of an aircraft engine). The test environment temperature in these occasions usually exceeds 600°C, or even as high as 1000°C. Such harsh environmental test conditions not only require the sensor to be able to work normally in a high-temperature environment, but also need to meet the requirements of high-precision measurement. At present, the operating temperature of most common piezoelectric accelerometers on the market is below 200°C, which can no longer meet the application requirements in some high-temperature projects. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a shear-type high-temperature piezoelectric acceleration sensor structure, which has a simple structure and is easy to assemble, can realize vibration monitoring in a high-temperature environment of >200°C, and has a relatively stable sensitivity.

[0005] The technical solution of the utility model is as follows:

[0006] A shear-type high-temperature piezoelectric acceleration sensor structure comprises a base, a central column arranged on the base, and a wedge-shaped pre-tightening block, a piezoelectric sheet group, a mass block and a square shell which are sequentially arranged outside the central column from the inside to the outside. The piezoelectric sheet group is composed of two piezoelectric single crystals located on both sides of the central column connected in parallel. The piezoelectric sheet group is sleeved outside the central column and forms a gap with the central column. The mass block is sleeved on the outer surface of the piezoelectric sheet group. The square shell is sleeved on the outer surface of the mass block. The outer surface of the central column is processed into a slope surface less than 90°. The wedge-shaped pre-tightening block is inserted in the gap between the piezoelectric sheet group and the central column, and its inner surface is interference fit with the slope surface of the outer surface of the central column. Bolts are threadedly connected on the central column, and the radial force required for the cooperation between the piezoelectric sheet group, the mass block and the central column is provided by pressing down the wedge-shaped pre-tightening block with the bolts.

[0007] Furthermore, a first threaded hole extending along the central axis is provided on the bottom surface of the base, and the vibration table is connected through the first threaded hole during testing.

[0008] Furthermore, the base is externally grounded.

[0009] Furthermore, the slope of the outer surface of the central column is 85°.

[0010] Furthermore, a second threaded hole extending along the central axis is provided on the top surface of the central column, and the bolt is threadedly connected to the second threaded hole.

[0011] Furthermore, two or more groups are provided inside and outside the piezoelectric sheet group, and insulating sheets are sleeved between the piezoelectric sheet group and the wedge-shaped preload block and the mass block. Electrode sheets are used to collect and conduct charges between the piezoelectric sheet groups and between the piezoelectric sheet groups and the insulating sheets.

[0012] Compared with the prior art, the beneficial effects of the utility model are as follows: the utility model adopts a square shell and a wedge-shaped pre-tightening block to fix and pre-tighten the sensor structure, avoiding the disadvantages of the traditional shear structure that uses bolts to fix and requires punching holes in the piezoelectric sheet, the insulating sheet and the electrode sheet; and by using a wedge-shaped pre-tightening block for pre-tightening, the force-bearing area is increased and the force is more uniform; in addition, it also has good high-temperature corrosion resistance and oxidation resistance, and can enable the sensor to be used in a high-temperature environment of >200°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art 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 work.

[0014] Figure 1 A schematic diagram of a shear-type high-temperature piezoelectric acceleration sensor structure provided in the first embodiment of the utility model;

[0015] Figure 2 This is a structural schematic diagram of a shear-type high-temperature piezoelectric acceleration sensor structure provided in Example 2 of the utility model. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0017] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0018] Embodiment 1

[0019] See also Figure 1 This embodiment provides a shear-type high-temperature piezoelectric acceleration sensor structure, including a base 1, a central column 2 arranged on the base 1, and a wedge-shaped pre-tightening block 8, a piezoelectric sheet group 6, a mass block 4 and a square housing 3 arranged outside the central column 2 from the inside to the outside. The bottom surface of the base 1 is provided with a first threaded hole extending along the central axis. During testing, the vibration table is connected through the first threaded hole, which is safe and reliable and convenient for loading and unloading; the base 1 is externally connected to the ground wire 10 to avoid the interference of the power frequency signal of the traditional sensor during the test process, making the test simpler and more accurate. The piezoelectric sheet group 6 is composed of two piezoelectric single crystals located on both sides of the central column in parallel. The piezoelectric sheet group 6 is sleeved outside the center column 2, and a gap is formed between the piezoelectric sheet group 6 and the center column 2. The mass block 4 is sleeved on the outer surface of the piezoelectric sheet group 6 without a gap. The square shell 3 is sleeved on the outer surface of the mass block 4 without a gap. The outer surface of the center column 2 is processed into a slope less than 90°, which is 85° in this embodiment. The wedge-shaped pre-tightening block 8 is inserted in the gap between the piezoelectric sheet group 6 and the center column 2, and its inner surface is interference-fitted with the slope of the outer surface of the center column 2. The top surface of the center column 2 is provided with a second threaded hole extending along the axis of the center axis. The second threaded hole is threadedly connected with a bolt 7. The bolt 7 presses down and squeezes the wedge-shaped pre-tightening block 8 to provide the radial force required for the cooperation between the piezoelectric sheet group 6 and the mass block 4 and the center column 2. By using the square shell 3 and the wedge-shaped pre-tightening block 8 to fix and pre-tighten the sensor structure, the disadvantages of the traditional shear structure being fixed by bolts and needing to punch holes in the piezoelectric sheet, the insulating sheet and the electrode sheet are avoided; and by using the wedge-shaped pre-tightening block 8 for pre-tightening, the force-bearing area is increased and the force is more uniform.

[0020] In this embodiment, the base 1, the center column 2, the bolt 7, the wedge-shaped preload block 8, the mass block 4, and the square housing 3 are all made of the high-temperature resistant nickel-chromium alloy Inconel 601, which has good high-temperature corrosion resistance and oxidation resistance, and can ensure the normal use of the sensor in a high-temperature environment.

[0021] In this embodiment, the piezoelectric single crystal piece adopts a high-temperature YCa4O(BO3)3 (YCOB) single crystal, which has stable piezoelectric properties at high temperatures and has no phase change and high resistivity phenomenon before the melting point (~1500°C), enabling the sensor to be used in a high-temperature environment of >200°C.

[0022] Embodiment 2

[0023] See also Figure 2 This embodiment provides a shear-type high-temperature piezoelectric acceleration sensor structure, which is different from the first embodiment in that two or more groups of piezoelectric sheet groups 6 are provided inside and outside, and insulating sheets 5 are sleeved between the piezoelectric sheet groups 6 and the wedge-shaped preload block 8 and the mass block 4. The piezoelectric sheet groups 6 and the piezoelectric sheet groups 6 and the insulating sheets 5 are used to collect and conduct charges through electrode sheets 9. When the first embodiment uses two piezoelectric single crystals, the electrode sheets 9 and the insulating sheets 5 may not be used, thereby avoiding the decrease in sensor sensitivity caused by poor contact between the electrode sheets 9 and the piezoelectric single crystal.

[0024] Preferably, the electrode sheet 9 is also made of nickel-chromium alloy Inconel601 having good high temperature corrosion resistance and oxidation resistance; and the insulating sheet 5 can be made of alumina ceramic sheet.

[0025] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A shear-type high-temperature piezoelectric acceleration sensor structure, characterized in that: It includes a base, a center column arranged on the base, and a wedge-shaped pre-tightening block, a piezoelectric sheet group, a mass block and a square shell which are arranged outside the center column in sequence from the inside to the outside. The piezoelectric sheet group is composed of two piezoelectric single crystals located on both sides of the center column in parallel. The piezoelectric sheet group is sleeved outside the center column to form a gap with the center column. The mass block is sleeved on the outer surface of the piezoelectric sheet group, and the square shell is sleeved on the outer surface of the mass block. The outer surface of the center column is processed into a slope surface less than 90°. The wedge-shaped pre-tightening block is inserted in the gap between the piezoelectric sheet group and the center column, and its inner surface is interference fit with the slope surface of the outer surface of the center column. Bolts are threadedly connected on the center column, and the radial force required for the cooperation between the piezoelectric sheet group, the mass block and the center column is provided by pressing down the wedge-shaped pre-tightening block with the bolts.

2. A shear-type high-temperature piezoelectric acceleration sensor structure according to claim 1, characterized in that: The bottom surface of the base is provided with a first threaded hole extending along the central axis, and the vibration table is connected through the first threaded hole during testing.

3. The shear-type high-temperature piezoelectric acceleration sensor structure according to claim 1, characterized in that: The base is externally grounded.

4. The shear-type high-temperature piezoelectric acceleration sensor structure according to claim 1, characterized in that: The slope of the outer surface of the central column is 85°.

5. The shear-type high-temperature piezoelectric acceleration sensor structure according to claim 1, characterized in that: The top surface of the central column is provided with a second threaded hole extending along the central axis, and the bolt is threadedly connected to the second threaded hole.

6. The shear-type high-temperature piezoelectric acceleration sensor structure according to claim 1, characterized in that: Two or more piezoelectric sheet groups are provided inside and outside the piezoelectric sheet group. Insulating sheets are sleeved between the piezoelectric sheet group and the wedge-shaped preload block and the mass block. Electrode sheets are used to collect and conduct charges between the piezoelectric sheet groups and between the piezoelectric sheet groups and the insulating sheets.

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