A vibration transmission structure of a high temperature vibration sensor calibration device

Abstract

The present invention discloses a vibration transmission structure of a high-temperature vibration sensor calibration device, including a vibration transmission structure body and a lateral auxiliary mechanism, wherein the vibration transmission structure body is divided into an upper transmission structure section and a lower transmission structure section, wherein the upper transmission structure section is a cylindrical metal structure, and the lower transmission structure section is a cylindrical ceramic structure; the upper end surface of the upper transmission structure section is provided with a plurality of threaded holes for rigidly connecting with a vibration sensor to be calibrated, the lower end surface is provided with a plurality of threaded holes for rigidly connecting with the lower transmission structure section, the lower transmission structure section is provided with a plurality of through holes for rigidly connecting with a vibration table of the high-temperature vibration sensor calibration device and the upper transmission structure section, and a threaded hole is provided at the center position of the lower end surface of the lower transmission structure section for back-to-back installation of a standard sensor. The present invention can improve the uniformity of acceleration amplitude under vibration-temperature composite stress conditions, and effectively improve the test and calibration accuracy of high-temperature vibration sensors.

Description

Technical Field

[0001] The invention belongs to the technical field of vibration measurement and testing, and in particular relates to a vibration transfer structure of a high-temperature vibration sensor calibration device and a vibration transfer coefficient calibration method. Background Art

[0002] High temperature vibration sensors are widely used in vibration monitoring of mechanical equipment such as aerospace engines and various steam turbine generator sets. There are large differences in their output at different temperatures. At present, the calibration of high temperature vibration sensors is mainly based on the two standards "JJG233-2008 Piezoelectric Accelerometer Verification Procedure" and "ISO 16063-34 Methods for the calibration of vibration and shock transducers-Part34: Testing of sensitivity at fixed temperatures". The calibration methods include comparison method and absolute method. The comparison method generally requires the standard sensor and the calibrated sensor to be installed back to back, and the absolute method requires the laser measurement position to be as close as possible to the installation position of the high temperature vibration sensor to reduce the impact of uneven acceleration distribution.

[0003] As a key component of the high-temperature vibration sensor calibration device, the vibration transfer structure transfers vibration from room temperature to high temperature environment, and its design directly affects the vibration transfer effect. At present, the vibration transfer structure mainly considers the parameter design of heat insulation, weight reduction and resonance frequency, and the vibration transfer structure is hollowed out. The uniformity of acceleration distribution under vibration-temperature composite stress conditions is not considered, resulting in the standard vibration sensor can only be installed on the vibration table during comparative calibration, which does not meet the back-to-back installation requirements of relevant standards; during absolute calibration, the difference in acceleration measurement caused by the difference between the sensor measurement position and the laser measurement position is unknown, all of which affect the calibration accuracy of the high-temperature vibration sensor. In addition, given that ceramic materials have the characteristics of low thermal conductivity, high strength and low density, ceramic materials are currently used for vibration transfer structures. However, during the test, it was found that if the temperature change rate is too fast, cracks may appear in the ceramic material, which directly affects the vibration transfer effect and reduces the reliability of the calibration device. Summary of the invention

[0004] The purpose of the present invention is to provide a vibration transfer structure and a vibration transfer coefficient calibration method for a high-temperature vibration sensor calibration device, which can improve the uniformity of acceleration amplitude under vibration-temperature composite stress conditions and effectively improve the test calibration accuracy of the high-temperature vibration sensor.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a vibration transmission structure of a high-temperature vibration sensor calibration device, comprising a vibration transmission structure body and a lateral auxiliary mechanism, wherein the vibration transmission structure body is divided into an upper transmission structure section and a lower transmission structure section, wherein the upper transmission structure section is a cylindrical metal structure, and the lower transmission structure section is a cylindrical ceramic structure;

[0006] The lateral auxiliary mechanism is a hollow cylindrical graphite structure, which is arranged outside the upper section of the transmission structure and forms a uniformly distributed air film with the upper section of the transmission structure, and is used to provide effective restraint force on the lateral vibration of the vibration transmission structure and reduce its lateral vibration ratio. The lateral auxiliary mechanism is fixed inside the temperature box of the high-temperature vibration sensor calibration device;

[0007] The upper end surface of the upper section of the transmission structure is provided with multiple threaded holes for rigid connection with the vibration sensor to be calibrated, and the lower end surface is provided with multiple threaded holes for rigid connection with the lower section of the transmission structure. The lower section of the transmission structure is provided with multiple through holes, which are respectively used for rigid connection with the vibration table of the high-temperature vibration sensor calibration device and the upper section of the transmission structure. A threaded hole is provided at the center position of the lower end surface of the lower section of the transmission structure for back-to-back installation of standard sensors.

[0008] Preferably, the upper section of the transfer structure is made of titanium alloy metal material, the lower section of the transfer structure is made of microcrystalline mica ceramic material, and the lateral auxiliary mechanism is made of porous graphite material.

[0009] Preferably, a symmetrical cylindrical hollow structure is provided inside the upper section of the transfer structure for effective transfer of heat insulation and vibration.

[0010] Another aspect of the present invention provides a vibration transfer coefficient calibration method for a high temperature vibration sensor calibration device, which uses the above-mentioned vibration transfer structure to calibrate the vibration transfer coefficient, comprising:

[0011] The reference acceleration sensor is rigidly mounted on the center position of the lower end surface of the vibration transmission structure by screws, the vibration transmission structure is rigidly connected to the table top of the vibration table of the high-temperature vibration sensor calibration device by screws, a laser vibrometer is installed above the temperature box of the high-temperature vibration sensor calibration device, and the laser incident position is adjusted so that it is vertically incident on the center position of the upper end surface of the vibration transmission structure;

[0012] Conduct vibration tests within the working frequency range, perform vibration tests at different temperatures and frequencies, calculate the ratio of the upper end face acceleration to the lower end face acceleration of the vibration transfer structure based on the acceleration output of the reference acceleration sensor and the laser vibrometer, and obtain the vibration transfer coefficient at the corresponding discrete frequency point;

[0013] According to the vibration transfer coefficient at discrete frequency points, a continuous "frequency-vibration transfer coefficient" calibration data table is obtained through cubic Hermite interpolation, which is used for compensation correction of vibration transfer under high temperature.

[0014] Preferably, cubic Hermite interpolation is performed as follows:

[0015]

[0016] Among them, y(x n ) is the discrete sequence of vibration transmission coefficient, n is the number of discrete frequency points, x i and y(x i ) represent the frequency and corresponding vibration transmission coefficient of the ith point, y′(x i ) is the discrete sequence of vibration transmission coefficients at x i The first-order derivative value at , H(x) is the interpolation function on [i-1, i].

[0017] Preferably, the compensation correction of vibration transmission at high temperature is performed as follows:

[0018] According to the measured vibration frequency, find the "frequency-vibration transfer coefficient" calibration data table, determine the corresponding vibration transfer coefficient, and calculate the reference vibration acceleration when calibrating the vibration sensor by the comparison method in real time:

[0019] a=V1b1r / S1G1

[0020] in:

[0021] a is the reference vibration acceleration;

[0022] V1 is the measured voltage of the reference acceleration sensor;

[0023] b1 is the sensitivity parameter of the reference acceleration sensor’s conditioning amplifier setting;

[0024] r is the vibration transmission coefficient;

[0025] S1 is the sensitivity of the reference acceleration sensor;

[0026] G1 is the gain parameter of the reference acceleration sensor's conditioning amplifier.

[0027] The vibration transfer structure and vibration transfer coefficient calibration method of the high-temperature vibration sensor calibration device according to the above aspects of the present invention can improve the uniformity of acceleration amplitude under vibration-temperature composite stress conditions, and improve the test calibration accuracy of the high-temperature vibration sensor by calibrating the vibration transfer coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0029] Figure 1 A schematic structural diagram of a vibration transmission structure of a high temperature vibration sensor calibration device according to an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the structure of a high temperature vibration sensor calibration device according to an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the vibration transfer coefficient of the vibration transfer structure of one embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. 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.

[0033] An embodiment of the present invention provides a vibration transmission structure of a high temperature vibration sensor calibration device, such as Figure 1 As shown, the vibration transmission structure 4 of the embodiment of the present invention includes a vibration transmission structure body and a lateral auxiliary mechanism 107. The vibration transmission structure body is divided into two sections: an upper section 101 of the transmission structure and a lower section 102 of the transmission structure, wherein the upper section 101 of the transmission structure is a cylindrical metal structure with an internal heat insulation and weight reduction design; the lower section 102 of the transmission structure is a cylindrical ceramic structure with a hollow cylindrical tube inside, and the upper and lower sections are rigidly connected by screws. The lateral auxiliary mechanism 107 is a cylindrical graphite structure with a hollow cylindrical tube inside, and is arranged outside the upper section 101 of the transmission structure. In one embodiment, the upper section 101 of the transmission structure is made of titanium alloy metal material, the lower section 102 of the transmission structure is made of microcrystalline mica ceramic material, and the lateral auxiliary mechanism 107 is made of porous graphite material.

[0034] A symmetrical cylindrical hollow structure is provided inside the upper section 101 of the transmission structure for effective transmission of heat insulation and vibration. The upper end surface 103 is provided with a plurality of threaded holes for rigid connection with the vibration sensor to be calibrated, and the lower end surface 104 is provided with a threaded hole for rigid connection with the ceramic structure of the lower section 102 of the transmission structure. The lower section 102 of the transmission structure is provided with a plurality of through holes, which are respectively used for rigid connection with the vibration table and the metal structure of the upper section 101 of the transmission structure. A threaded hole is provided at the center of the lower end surface 106 of the lower section 102 of the transmission structure for back-to-back installation of sensors.

[0035] The vibration transmission structure 4 can work at a temperature as high as 800° C. by using different materials and combining them in sections. The acceleration amplitude uniformity of the upper end surface 103 of the top of the structure, which is used as the mounting surface of the sensor to be calibrated, is better than 10%.

[0036] The upper section 101 of the transmission structure and the lower section 102 of the transmission structure are connected by threads, and the lateral auxiliary mechanism 107 is fixed inside the temperature box of the high-temperature vibration sensor calibration device. The lateral auxiliary mechanism 107 is a high-temperature resistant radial porous cylindrical hollow structure, which forms a uniformly distributed air film between it and the upper section 101 of the transmission structure, which can provide effective restraint force on the lateral vibration of the vibration transmission structure 4 and reduce its lateral vibration ratio.

[0037] The vibration transmission structure of the embodiment of the present invention can be applied to Figure 2 The high temperature vibration sensor calibration device shown in the figure comprises a vibration table 1, a power amplifier 2, a reference acceleration sensor 3, a vibration transmission structure 4, a vibration sensor to be calibrated 5, a temperature sensor 6, a temperature box 7, a temperature control module 8, an adjustment amplifier 9, and a computer control acquisition module 10. The vibration transmission structure 4 is rigidly connected to the table of the vibration table 1, the reference acceleration sensor 3 is installed on the lower end surface of the vibration transmission structure 4, the vibration sensor to be calibrated 5 is installed on the upper end surface of the vibration transmission structure 4 and is in the temperature box 7, and the temperature sensor 6 is installed in the temperature box 7.

[0038] The adaptive amplifier 9 receives the standard output and the calibrated output of the reference acceleration sensor 3 and the calibrated vibration sensor 5 respectively, and transmits them to the computer control acquisition module 10. The computer control acquisition module 10 processes data according to the standard output and the calibrated output, calibrates the vibration sensor by comparison method, and controls the vibration of the vibration table 1 through the power amplifier 2. The temperature control module 8 receives the temperature data of the temperature sensor 6 and controls the temperature of the temperature box 7 under the control of the computer control acquisition module 10.

[0039] An embodiment of the present invention further provides a vibration transfer coefficient calibration method for a high-temperature vibration sensor calibration device, which uses the vibration transfer structure of the above embodiment to calibrate the vibration transfer coefficient. The calibration method process is as follows.

[0040] First, assemble the high-temperature vibration sensor calibration device. Rigidly install the reference acceleration sensor 3 at the bottom center of the vibration transmission structure 4 (the center of the lower end surface of the lower section 102 of the transmission structure) with screws; reasonably adjust the up and down positions of the temperature box 7, and rigidly connect the vibration transmission structure 4 to the vibration table 1 with screws; install the laser vibrometer above the temperature box 7, and adjust the laser incident position so that it is vertically incident on the center of the top of the vibration transmission structure 4.

[0041] Secondly, vibration tests are carried out within the working frequency range. Vibration tests are performed at different temperatures and frequencies. The vibration acceleration of the upper and lower end surfaces of the vibration transfer structure are measured in real time. The vibration transfer coefficient is obtained through the amplitude ratio of the vibration acceleration of the upper and lower end surfaces of the vibration transfer structure.

[0042] First, the vibration transfer coefficient was calibrated at room temperature. The vibration frequencies of the high-temperature vibration sensor calibration device were set to 20 Hz, 40 Hz, 80 Hz, 160 Hz, 315 Hz, 630 Hz, 1000 Hz, 1250 Hz, 1500 Hz, and 2000 Hz, respectively. The acceleration outputs of the reference accelerometer and the laser vibrometer were measured and recorded. The excitation frequency was set to 160 Hz, and the vibrations were measured at 1 m / s 2 、10m / s 2 、20m / s 2 、50m / s 2 , 100m / s 2 Measure and record the acceleration output of the reference accelerometer and the laser vibrometer at the acceleration vibration level.

[0043] The calibration temperature points were set to 100℃, 200℃, 500℃, and 600℃, and their corresponding heating and holding times. After reaching the corresponding temperature and holding for a period of time, the vibration frequencies of the high-temperature vibration sensor calibration device were set to 20Hz, 40Hz, 80Hz, 160Hz, 315Hz, 630Hz, 1000Hz, 1250Hz, 1500Hz, and 2000Hz, respectively. The acceleration outputs of the reference acceleration sensor and the laser vibrometer were measured and recorded. The excitation frequency was set to 160Hz, and the acceleration was measured at 1m / s 2 、10m / s 2 、20m / s 2 、50m / s 2 , 100m / s 2 Measure and record the acceleration output of the reference accelerometer and the laser vibrometer at the acceleration vibration level until the vibration test at the above temperature points is completed.

[0044] Based on the vibration acceleration test data at different temperatures and frequencies, the ratio of the upper end surface acceleration to the lower end surface acceleration of the vibration transfer structure is calculated to obtain the vibration transfer coefficient at the corresponding discrete frequency point, such as Figure 3 As shown. Based on the cubic Hermite interpolation, a continuous "frequency-vibration transfer coefficient" calibration data table is obtained. When calibrating the sensor to be calibrated, the above "frequency-vibration transfer coefficient" calibration data table is automatically searched to determine the corresponding compensation correction coefficient, and the high-precision calibration of the high-temperature vibration sensor is completed.

[0045] The vibration transfer coefficient calibration method of the embodiment of the present invention considers the transmission capacity of the vibration transfer structure 4 to perform calibration compensation of the vibration transfer coefficient, and converts the transfer coefficient at discrete frequency points into a continuous "frequency-vibration transfer coefficient" calibration data table based on interpolation, thereby calibrating the vibration transfer coefficient within the entire frequency range, which is used for compensation and correction of vibration transfer under high temperature, ensuring the accuracy of vibration magnitude and improving calibration accuracy.

[0046] Among them, the characteristics of cubic Hermite interpolation are that the function value of the interpolation polynomial is the same as the original function value, and the first-order derivative value of the interpolation polynomial is equal to the first-order derivative value of the interpolated function. The cubic Hermite interpolation method is implemented as follows:

[0047] Assume that y(x n ) is the discrete sequence of vibration transmission coefficient, n is the number of discrete frequency points, x i and y(x i ) represent the frequency and corresponding vibration transmission coefficient of the i-th point respectively, and let H(x) be the interpolation function on [i-1, i], we have

[0048]

[0049]

[0050] Where:

[0051] H′(x) is the first-order derivative of the interpolation function H(x) on [i-1, i];

[0052] ψ i-1 (x), ψ i (x) is the interpolation basis function;

[0053] ψ′ i-1 (x),ψ′ i (x) is the first-order derivative of the interpolation basis function;

[0054] y′(x i-1 ), y′(x i) is the discrete sequence of vibration transmission coefficients at x i-1 and x i The first-order derivative value at .

[0055] Combining the above formulas (1) to (3), we have

[0056]

[0057] Similarly, the interpolation functions of other subintervals can be determined, and then the interpolation function of the entire interval can be determined.

[0058] In one embodiment, using Figure 2 When the high temperature vibration sensor calibration device shown in the figure is calibrated by the comparative method, the "frequency-vibration transfer coefficient" calibration data table is searched according to the measured vibration frequency, the corresponding vibration transfer coefficient is determined, and the reference vibration acceleration a is calculated in real time to achieve accurate calculation and control of the magnitude and avoid "over-testing" or "under-testing". The calculation formula is as follows:

[0059] a=V1b1r / S1G1 (5)

[0060] Where:

[0061] a is the reference vibration acceleration, m / s 2 ;

[0062] V1 is the reference acceleration sensor measurement voltage, mV;

[0063] b1 is the sensitivity parameter of the reference acceleration sensor’s conditioning amplifier setting, (mV / pC) / Unit;

[0064] r is the vibration transfer coefficient, the ratio of the accelerations of the upper and lower end surfaces of the vibration transfer structure;

[0065] S1 is the sensitivity of the reference acceleration sensor, (mV / pC) / (m / s 2 );

[0066] G1 is the gain parameter of the reference acceleration sensor's conditioning amplifier setting, mV / Unit.

[0067] To sum up, the vibration transfer structure of the high-temperature vibration sensor calibration device in the embodiment of the present invention is a highly uniformly distributed vibration transfer structure under vibration-temperature composite stress conditions, which can achieve accurate transmission of vibrations in the frequency range of 20Hz to 2000Hz in a high-temperature environment, and the uniformity of acceleration amplitude is better than 10%.

[0068] The vibration transmission structure of the high temperature vibration sensor calibration device according to the embodiment of the present invention has the following beneficial effects:

[0069] (1) The present invention comprehensively selects materials such as metals and ceramics, and is designed as a two-stage structure combined with a lateral auxiliary mechanism. Its thermal insulation, distortion, lateral vibration ratio, and acceleration amplitude uniformity all meet the requirements, ensuring the reliability and accuracy of the high-temperature vibration sensor calibration device.

[0070] (2) The present invention can meet the requirement of back-to-back installation of sensors during calibration by the vibration sensor comparison method, and at the same time, compensate and correct the transfer coefficient of the vibration transfer structure, which is beneficial to improving the calibration accuracy of the temperature sensitivity of the vibration sensor.

[0071] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A vibration transmission structure of a high temperature vibration sensor calibration device, characterized in that: It includes a vibration transmission structure body and a lateral auxiliary mechanism, wherein the vibration transmission structure body is divided into an upper transmission structure section and a lower transmission structure section, the upper transmission structure section is a cylindrical metal structure, and the lower transmission structure section is a cylindrical ceramic structure; The lateral auxiliary mechanism is a hollow cylindrical graphite structure, which is arranged outside the upper section of the transmission structure and forms a uniformly distributed air film with the upper section of the transmission structure, and is used to provide effective restraint force on the lateral vibration of the vibration transmission structure and reduce its lateral vibration ratio. The lateral auxiliary mechanism is fixed inside the temperature box of the high-temperature vibration sensor calibration device; The upper end surface of the upper section of the transmission structure is provided with multiple threaded holes for rigid connection with the vibration sensor to be calibrated, and the lower end surface is provided with multiple threaded holes for rigid connection with the lower section of the transmission structure. The lower section of the transmission structure is provided with multiple through holes, which are respectively used for rigid connection with the vibration table of the high-temperature vibration sensor calibration device and the upper section of the transmission structure. A threaded hole is provided at the center position of the lower end surface of the lower section of the transmission structure for back-to-back installation of standard sensors.

2. The vibration transmission structure according to claim 1, characterized in that: The upper section of the transmission structure is made of titanium alloy metal material, the lower section of the transmission structure is made of microcrystalline mica ceramic material, and the lateral auxiliary mechanism is made of porous graphite material.

3. The vibration transmission structure according to claim 1 or 2, characterized in that: A symmetrical cylindrical hollow structure is arranged inside the upper section of the transfer structure for effective transmission of heat insulation and vibration.

4. A vibration transfer coefficient calibration method for a high temperature vibration sensor calibration device, characterized in that: Calibration of the vibration transfer coefficient using the vibration transfer structure according to any one of claims 1 to 3 comprises: The reference acceleration sensor is rigidly mounted on the center position of the lower end surface of the vibration transmission structure by screws, the vibration transmission structure is rigidly connected to the table top of the vibration table of the high-temperature vibration sensor calibration device by screws, a laser vibrometer is installed above the temperature box of the high-temperature vibration sensor calibration device, and the laser incident position is adjusted so that it is vertically incident on the center position of the upper end surface of the vibration transmission structure; Conduct vibration tests within the working frequency range, perform vibration tests at different temperatures and frequencies, calculate the ratio of the upper end face acceleration to the lower end face acceleration of the vibration transfer structure based on the acceleration output of the reference acceleration sensor and the laser vibrometer, and obtain the vibration transfer coefficient at the corresponding discrete frequency point; According to the vibration transfer coefficient at discrete frequency points, a continuous "frequency-vibration transfer coefficient" calibration data table is obtained through cubic Hermite interpolation, which is used for compensation correction of vibration transfer under high temperature.

5. The method according to claim 4, characterized in that Perform cubic Hermite interpolation as follows: Among them, y(x n ) is the discrete sequence of vibration transmission coefficient, n is the number of discrete frequency points, x i and y(x i ) represent the frequency and corresponding vibration transmission coefficient of the ith point, y′(x i ) is the discrete sequence of vibration transmission coefficients at x i The first-order derivative value at , H(x) is the interpolation function on [i-1, i].

6. The method according to claim 4 or 5, characterized in that The compensation correction for vibration transmission at high temperature is carried out as follows: According to the measured vibration frequency, find the "frequency-vibration transfer coefficient" calibration data table, determine the corresponding vibration transfer coefficient, and calculate the reference vibration acceleration when calibrating the vibration sensor by the comparison method in real time: a=V1b1r / S1G1 in: a is the reference vibration acceleration; V1 is the measured voltage of the reference acceleration sensor; b1 is the sensitivity parameter of the reference acceleration sensor’s conditioning amplifier setting; r is the vibration transmission coefficient; S1 is the sensitivity of the reference acceleration sensor; G1 is the gain parameter of the reference acceleration sensor's conditioning amplifier.

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