High-temperature-resistant and high-stability quartz flexible accelerometer and design method thereof

Abstract

The application discloses a high-temperature-resistant and high-stable quartz flexible accelerometer and a design method thereof, and relates to the technical field of accelerometers. The technical scheme points of the application comprise a shell, a sensitive unit arranged in the shell, and a buffer isolation structure connected to the sensitive unit. The sensitive unit is used for sensing acceleration and outputting a corresponding signal, and comprises a quartz pendulum piece assembly and a magnetic steel assembly used for providing a magnetic field for the quartz pendulum piece assembly. The buffer isolation structure is used for attenuating mechanical vibration and impact energy transmitted from the shell to the sensitive unit. The magnetic steel assembly is made of a samarium-cobalt-based permanent magnet material, and at least two heavy rare earth elements are doped in the samarium-cobalt-based permanent magnet material. The effect is to improve the overall working reliability and service life.

Description

Technical Field

[0001] This invention relates to the field of accelerometer technology, and more specifically, to a high-temperature resistant and highly stable quartz flexible accelerometer and its design method. Background Technology

[0002] Quartz flexible accelerometers are key sensors in measurement-while-drilling (MWD) systems. By sensing gravitational acceleration and its components, these sensors calculate crucial parameters such as the azimuth and inclination angles of the wellbore trajectory, providing critical feedback data for real-time navigation and control of the downhole drill bit. This allows the drill bit to avoid risky areas such as faults and abrupt lithological changes, significantly reducing stuck pipe and miss-target accidents caused by trajectory deviations. However, the harsh operating environment of ultra-deep drilling places even more stringent environmental adaptability requirements on quartz flexible accelerometers, including resistance to high temperatures, strong vibrations, and shocks.

[0003] Quartz flexible accelerometers rely on a flexible support structure of quartz pendulums to sense and convert acceleration. Unlike applications such as navigation systems and seismic monitoring, which are mostly characterized by relatively regular low-frequency vibrations and short-term impacts, the flexible beams of quartz pendulums in downhole environments, where low-frequency and high-frequency vibrations coexist with intermittent large impacts, are prone to microcrack propagation, structural fatigue, and even brittle fracture, significantly affecting the reliability of the accelerometer downhole. Furthermore, quartz flexible accelerometers are systems involving the coupling of various materials and components, including quartz, magnetic materials, epoxy adhesives, stainless steel, aluminum alloys, and electronic components. High-temperature environments of 200°C and above will cause significant deformation of key sensitive structures within the accelerometer, while long-term exposure to high temperatures will lead to creep and accelerated aging of the sensor materials. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a high-temperature resistant and highly stable quartz flexible accelerometer and its design method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-temperature resistant and highly stable quartz flexible accelerometer includes a housing, a sensing unit disposed within the housing, and a buffer isolation structure connected to the sensing unit.

[0007] The sensitive unit is used to sense acceleration and output a corresponding signal. The sensitive unit includes a quartz pendulum assembly and a magnet assembly for providing a magnetic field to the quartz pendulum assembly. The buffer isolation structure is used to attenuate the mechanical vibration and impact energy transmitted from the outer shell to the sensitive unit.

[0008] The flexible beam structure parameters of the quartz pendulum assembly are optimized so that the maximum stress of the flexible beam is less than the allowable stress of the quartz material under preset static, vibration and impact loads, so that the swing amount of the quartz pendulum assembly is within the preset sensitivity range.

[0009] The magnet assembly is made of samarium cobalt-based permanent magnet material, and the samarium cobalt-based permanent magnet material is composite doped with at least two heavy rare earth elements.

[0010] Preferably, the buffer isolation structure is a double isolation ring structure, which includes an inner isolation ring and an outer isolation ring coaxially sleeved together.

[0011] Preferably, the magnetic steel assembly is composed of Sm(1-x)HREx(Co) 0.7 Fe 0.2 Cu 0.08 Zr 0.02 )z;

[0012] HRE represents heavy rare earth elements, and HRE includes gadolinium, dysprosium, and erbium; where 0 < x < 1, and z is a number between 7 and 8.

[0013] Preferably, the specific composition of the magnet assembly is Sm 0.6 HRE 0.4 (Co 0.7 Fe 0.2 Cu 0.08 Zr 0.02 ) 7.2 ;

[0014] Where HRE = Gd 0.87 Dy 0.065 Er 0.065 .

[0015] Preferably, the thickness of the flexible beam is 0.02mm~0.05mm, the width of the flexible beam is 3.7mm~4.2mm, the maximum stress of the flexible beam does not exceed 50MPa, and the sway of the flexible beam is 1.3mm~1.6mm.

[0016] A design method for a high-temperature resistant and highly stable quartz flexible accelerometer includes the following steps:

[0017] Determine the sensitivity of the structural parameters of the flexible beam to the stress of the flexible beam; wherein the structural parameters include at least the thickness, width and distance from the root of the beam to the centroid of the quartz pendulum.

[0018] After determining the optimization order based on the impact sensitivity, the parameters of the flexible beam are adjusted; among them, the parameters that have the greatest impact on the stress of the flexible beam are optimized first.

[0019] The stress state of the adjusted flexible beam under static, vibration and impact loads was verified through finite element simulation until the preset stress conditions were met and the optimal design parameters were achieved so that the swing of the quartz pendulum reached the predetermined target.

[0020] Preferably, the optimization order is as follows: optimizing the thickness of the flexible beam, the width of the flexible beam, and the distance from the root of the beam to the centroid of the quartz pendulum.

[0021] Preferably, the method for preparing the magnet assembly includes the following steps:

[0022] Raw materials were prepared according to the composition ratio of the magnet components, and alloy powder was prepared by ball milling.

[0023] The alloy powder is dried.

[0024] Orienting of dried alloy powder in a magnetic field;

[0025] The oriented alloy powder is sequentially pressed, sintered, and homogenized to obtain a blank.

[0026] The billet is subjected to aging treatment to obtain a magnetic steel assembly.

[0027] Preferably, the average particle size of the alloy powder is controlled to be 4-5 micrometers; the strength of the orientation magnetic field is 2-3 Tesla.

[0028] Preferably, sintering is carried out at 1200~1250℃ for 1~2 hours, and homogenization treatment is carried out at 1150~1200℃ for 3 hours;

[0029] The aging process is as follows: hold at 860℃ for 11 hours, cool to 450℃ at a rate of 0.5℃ / minute, and hold at 450℃ for 3.5 hours.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] In this invention, the sensitive unit is used to sense acceleration and output a corresponding signal. The buffer isolation structure effectively attenuates the mechanical vibration and impact energy transmitted from the outer shell to the sensitive unit, providing a stable working environment for the core measurement components. This avoids external mechanical interference directly affecting the acquisition and output of acceleration signals, significantly improving the accelerometer's anti-interference capability and stability under strong vibration and high impact conditions. The flexible beam structure parameters of the quartz pendulum assembly are optimized. Under preset static, vibration, and impact loads, the maximum stress of the flexible beam is less than the allowable stress of the quartz material. This ensures the structural strength of the flexible beam, preventing fatigue fracture or structural failure, while also keeping the pendulum swing of the quartz pendulum assembly within the preset sensitivity range. This achieves a balance between structural reliability and measurement sensitivity, ensuring that the accelerometer can stably output high-precision acceleration signals under complex load conditions, while extending the service life of the equipment. The magnet assembly is made of samarium-cobalt-based permanent magnet material, with at least two heavy rare earth elements incorporated into the material. This significantly increases the Curie temperature and coercivity of the magnet, reducing its magnetic properties, especially the decay rate of remanent magnetic induction with temperature changes. This allows the magnet assembly to maintain a stable and uniform magnetic field output even at high temperatures, providing a reliable working magnetic field for the quartz pendulum assembly. It prevents magnetic field fluctuations caused by temperature changes from affecting the accelerometer's measurement accuracy, significantly improving the sensor's high-temperature resistance and long-term operational stability. It can meet the high-precision acceleration measurement requirements under harsh conditions such as high temperature and strong vibration, effectively expanding the sensor's applicable scenarios and improving overall operational reliability and service life. Attached Figure Description

[0032] Figure 1 A schematic diagram of a high-temperature resistant and highly stable quartz flexible accelerometer provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the optimal design parameters for the quartz pendulum flexible beam in an embodiment of the present invention;

[0034] Figure 3 This is a flowchart illustrating the preparation of highly stable magnets in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of a high-temperature resistant and highly stable quartz flexible accelerometer in three axes, provided in an embodiment of the present invention.

[0036] Figure 5 This is a diagram showing the relationship between the width of the flexible support structure and the stress in an embodiment of the present invention;

[0037] Figure 6 This is a diagram showing the relationship between the thickness and stress of the flexible support structure in an embodiment of the present invention;

[0038] Figure 7 This is a diagram showing the relationship between the distance from the root of the flexible beam to the center of mass and the stress in an embodiment of the present invention.

[0039] Figure 8 This is a comparison diagram of simulation results before and after optimization of the quartz pendulum in an embodiment of the present invention;

[0040] Figure 9 This is a comparison diagram of simulation results before and after optimization of the dual isolation ring packaging structure in this embodiment of the invention;

[0041] Figure 10 The results of the high-temperature long-term operation accelerometer test in the embodiments of the present invention. Figure 1 ;

[0042] Figure 11 The results of the high-temperature long-term operation accelerometer test in the embodiments of the present invention. Figure 2 ;

[0043] Figure 12 This is a graph showing the stability test results of zero bias and scaling factor during long-term operation at high temperature in an embodiment of the present invention. Detailed Implementation

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0045] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0046] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0047] Reference Figures 1-12 As shown.

[0048] The embodiments further illustrate the high-temperature resistant and highly stable quartz flexible accelerometer and its design method proposed in this invention.

[0049] A high-temperature resistant and highly stable quartz flexible accelerometer includes a housing 1, a sensing unit 2 disposed within the housing 1, and a buffer isolation structure 3 connecting the sensing unit 2 and the housing 1.

[0050] Sensing unit 2 is used to sense acceleration and output a corresponding signal. Sensing unit 2 includes a quartz pendulum assembly and a magnet assembly for providing a magnetic field to the quartz pendulum assembly.

[0051] The magnet assembly is made of samarium cobalt-based permanent magnet material, and the samarium cobalt-based permanent magnet material is composite doped with at least two heavy rare earth elements.

[0052] The quartz pendulum assembly is a direct acceleration sensing component. When acceleration is applied to the accelerometer, the quartz pendulum assembly produces displacement changes under the action of inertial force. The stable magnetic field provided by the magnet assembly is the condition for the quartz pendulum assembly to realize the conversion of displacement into electrical signal.

[0053] The magnet assembly is made of samarium cobalt-based permanent magnet material, and at least two heavy rare earth elements are composite doped into the samarium cobalt-based permanent magnet material. By composite doping with heavy rare earth elements, the temperature coefficient of its magnetic properties is reduced, the magnetic field attenuation of the magnet assembly under high temperature environment is suppressed, and the magnet assembly maintains a stable magnetic field output under high temperature conditions, providing a basic guarantee for the high temperature resistance and high stability performance of the accelerometer.

[0054] The composition of the magnet component is Sm(1-x)HREx(Co) 0.7 Fe 0.2 Cu 0.08 Zr 0.02 )z;

[0055] HRE represents heavy rare earth elements, and HRE includes gadolinium, dysprosium, and erbium; where 0 < x < 1, and z is a number between 7 and 8.

[0056] The composition of the magnet assembly is Sm(1-x)HREx(Co) 0.7 Fe 0.2 Cu 0.08 Zr 0.02 )z, where HRE represents heavy rare earth elements, and HRE includes gadolinium, dysprosium and erbium, where 0 is less than x and less than 1, and z is a number between 7 and 8. Samarium, as a matrix rare earth element, provides basic magnetic properties. Elements such as cobalt, iron, copper and zirconium are used to control the crystal structure and magnetocrystalline anisotropy of the material, optimize the magnetic energy product and coercivity of the material, and the composite doping of gadolinium, dysprosium and erbium can refine the grain structure of the material, reduce the irreversible movement of magnetic domains at high temperatures, and significantly improve the magnetic field stability of the magnetic steel component in a high-temperature environment.

[0057] The specific composition of the magnet assembly is Sm 0.6 HRE 0.4 (Co 0.7 Fe 0.2 Cu 0.08 Zr 0.02 ) 7.2 ;

[0058] Where HRE = Gd 0.87 Dy 0.065 Er 0.065 .

[0059] By adjusting the proportion of heavy rare earth elements, an optimal balance between magnetic properties and temperature stability is achieved. This ensures that the magnetic steel component has sufficient magnetic field strength while significantly improving its magnetic performance retention rate in high-temperature environments. It maintains a uniform and stable magnetic field output at high temperatures, avoiding magnetic field fluctuations caused by temperature changes. This ensures the stable operation of the quartz pendulum component, allowing for precise conversion of displacement changes into corresponding electrical signals when sensing acceleration. This guarantees high-precision acceleration measurement under harsh conditions of high temperature and strong vibration, improving the overall stability and reliability of the accelerometer.

[0060] The buffer isolation structure 3 is used to attenuate the mechanical vibration and impact energy transmitted from the outer shell to the sensitive unit 2; the buffer isolation structure 3 is a double isolation ring structure, which includes an inner isolation ring and an outer isolation ring coaxially sleeved.

[0061] The buffer isolation structure is used to attenuate the mechanical vibration and impact energy transmitted from the outer shell to the sensitive element 2, providing a stable working environment for the sensitive components of the quartz flexible accelerometer. This buffer isolation structure adopts a double-isolation ring structure, including an inner and outer isolation ring coaxially fitted together. Through a reasonable structural arrangement, the two isolation rings form two independent and more stable buffering and attenuation paths. When the outer shell is subjected to external mechanical vibration or impact along the IA direction, the energy is first transferred to the outer isolation ring. The outer isolation ring absorbs and consumes a portion of the impact and vibration energy through its elastic deformation and damping effect, weakening the peak load of high-frequency impacts and filtering out some high-frequency vibration components. The energy attenuated by the outer isolation ring is then transferred to the inner isolation ring. The inner isolation ring attenuates the remaining vibration and impact energy a second time through elastic deformation and damping, significantly reducing the vibration amplitude and impact load transmitted to the sensitive element. When the outer shell is subjected to external vibration or impact along the OA or PA direction, the double isolation rings provide a stable structure with fixed ends for the sensitive element, achieving attenuation of the vibration and impact load transmitted to the sensitive element. The dual-isolation ring encapsulation structure can effectively broaden the operating frequency band of the buffer isolation, achieve efficient attenuation of vibrations of different frequencies and impacts of different intensities, prevent external mechanical interference from being directly transmitted to the quartz pendulum assembly and magnet assembly, prevent the sensitive unit from being structurally damaged or having signal output distortion due to vibration and impact, and ensure the measurement accuracy and working stability of the accelerometer in complex mechanical environments.

[0062] Among them, the flexible beam structure parameters of the quartz pendulum assembly are optimized. Under preset static, vibration and impact loads, the maximum stress of the flexible beam is less than the allowable stress of the quartz material, so that the swing amount of the quartz pendulum assembly is within the preset sensitivity range.

[0063] The thickness of the flexible beam is 0.02mm~0.05mm, the width of the flexible beam is 3.7mm~4.2mm, the maximum stress of the flexible beam does not exceed 50MPa, and the sway of the flexible beam is 1.3mm~1.6mm.

[0064] The flexible beam is the structure that enables the elastic support of the quartz pendulum assembly. It must provide sufficient elastic deformation space for the pendulum to ensure the sensitivity of acceleration measurement, and maintain structural safety under vibration and impact loads to avoid fracture or fatigue failure caused by excessive stress.

[0065] By controlling the thickness and width of the flexible beam, the thickness is kept within the range of 0.02mm to 0.05mm, and the width is kept within the range of 3.7mm to 4.2mm. At the same time, the maximum stress of the flexible beam is ensured not to exceed 50MPa, which is less than the allowable stress of quartz material, thus ensuring that the flexible beam will not suffer structural damage under various working conditions.

[0066] When acceleration is applied to the pendulum, the flexible beam undergoes elastic bending deformation, causing the pendulum to swing downwards. The amount of downward swing directly determines the sensitivity of the accelerometer. The amount of downward swing of the flexible beam is controlled within the range of 1.3mm to 1.6mm. This ensures that the swing is large enough to convert the acceleration signal into displacement changes for high-sensitivity signal output, while avoiding excessive stress on the flexible beam or instability caused by excessive swing. This allows the quartz pendulum assembly to operate stably within the preset sensitivity range, while also meeting the structural reliability requirements under high-temperature, high-vibration, and high-impact conditions.

[0067] The quartz flexible accelerometer of this application can withstand high temperatures of 200°C, and its scaling factor temperature coefficient is [missing information]. Resistant to random vibration Impact resistance 2000g.

[0068] The specific test results for the quartz accelerometer's temperature resistance, scaling factor temperature coefficient, random vibration, and shock are as follows:

[0069] By integrating the high-performance samarium cobalt-based permanent magnet material proposed in this application into a quartz flexible accelerometer, the scaling factor temperature coefficient of the entire accelerometer was tested. This application uses a quartz flexible accelerometer calibration device for data acquisition. The main components of the calibration device include a high-precision power supply Keysight E36311A, a 7.5-digit digital multimeter Keysight 34420, a quartz flexible accelerometer mounting fixture (mounting surface flatness, parallelism, and perpendicularity all ≤2μm), a rotation mechanism (continuous rotation angle ±360°, angular position positioning error ≤0.5″, repeatability ≤0.03″), a temperature control device (temperature control range 30℃~230℃, temperature control accuracy ≤0.5℃), and a sampling resistor (resistance 840Ω, accuracy 0.01%, temperature drift 1ppm / ℃).

[0070] The test temperatures were set to room temperature, 45℃, 65℃, 85℃, 105℃, 125℃, 145℃, 165℃, 175℃, and 200℃, with a heating / cooling rate of ≤5℃ / min. The quartz accelerometer was powered on at ±15V. After verifying that the output function was normal, the temperature coefficient test began. The first temperature point was powered on for 5 minutes before testing. Each temperature point was held for 40 minutes before starting the four-position rotation and data acquisition at that temperature. A total of 5 quartz accelerometer prototypes were tested, numbered 1# to 5#. The test results are shown in Table 4. The results show that in the temperature range of 175℃ to 200℃, the maximum temperature coefficient of the quartz accelerometer's scaling factor is 233ppm / ℃.

[0071] Table 4. Test results of scale factor and temperature coefficient of quartz accelerometers

[0072]

[0073] Two quartz accelerometers (#3 and #4) were selected for a long-term stability test at 175℃. During the test, the accelerometers were continuously powered on and calibrated at four positions every 12 hours, recording their zero bias and scale factor. The test results are as follows: Figure 10 and Figure 11 As shown, this experiment was conducted at 175℃ for a total of 428 hours, with 36 calibrations performed during the experiment. After the experiment, the self-developed accelerometer functioned normally.

[0074] The zero bias and scale factor standard deviation obtained from 36 calibrations for each accelerometer were calculated to evaluate its stability during long-term high-temperature operation. The results are as follows: Figure 12 As shown.

[0075] The test results show that the accelerometer can maintain normal function during continuous operation at a high temperature of 175℃ for 428 hours, and the magnetic steel material has good long-term service performance at high temperature for 428 hours. In terms of performance retention, the zero bias stability of the accelerometer meets the application requirement of long-term stability ≤500μg for measurement-while-drilling accelerometers, and the scaling factor can reach 27.4ppm at high temperature after 428 hours.

[0076] To verify the environmental adaptability of the quartz accelerometer developed in this patent, high-temperature random vibration and shock tests were conducted on the quartz accelerometer prototype. The high-temperature random vibration test conditions are shown in Table 5.

[0077] Table 5. High-Temperature Random Vibration Test Conditions

[0078]

[0079] After the high-temperature random vibration test, the quartz accelerometer functioned normally, with a zero bias temperature coefficient change of ≤20μg / ℃ and a scaling factor temperature coefficient change of ≤5ppm / ℃. Its performance remained good and met the application requirements of downhole instruments.

[0080] The impact test conditions and results are shown in Table 6. The impact test adopted a step-by-step loading method, starting from a pulse acceleration of 1000g and gradually increasing the impact intensity by 100g per step until the accelerometer failed. Through destructive testing, the structural ultimate bearing capacity and impact margin of the accelerometer under extreme impact conditions were evaluated.

[0081] Table 6 Impact Test Conditions and Results

[0082]

[0083] Impact test results show that the accelerometer malfunctioned when the peak acceleration increased to 2260g@0.31ms. Therefore, its maximum withstandable impact strength was determined to be 2091g@0.33ms, fully verifying the ultimate load-bearing capacity and impact margin of the designed structure and high-reliability packaging in impact environments.

[0084] A design method for a high-temperature resistant and highly stable quartz flexible accelerometer includes the following steps:

[0085] The sensitivity of the structural parameters of the flexible beam to the stress of the flexible beam is determined. The structural parameters include at least the thickness, width, and distance from the root of the beam to the centroid of the quartz pendulum. The influence of each parameter on the stress distribution of the flexible beam is quantified to clarify the degree of influence of each parameter.

[0086] After determining the optimization order based on the sensitivity of the effects, the parameters of the flexible beam are adjusted. Among them, the parameters that have the greatest impact on the stress of the flexible beam are optimized first. In this embodiment, the optimization order is as follows: the thickness of the flexible beam, the width of the flexible beam, and the distance from the beam root to the centroid of the quartz pendulum. To improve optimization efficiency, the thickness, as the parameter with the most significant impact on the stress of the flexible beam, is adjusted first to quickly control the stress level and avoid stress exceeding the limit.

[0087] The stress state of the adjusted flexible beam under static, vibration and impact loads was verified through finite element simulation until the preset stress conditions were met and the optimal design parameters were achieved so that the swing of the quartz pendulum reached the predetermined target.

[0088] This ensures that the flexible beam will not experience fatigue fracture or structural failure under complex working conditions, while also ensuring that the swing range of the quartz pendulum meets the sensitivity requirements of the accelerometer.

[0089] When a quartz pendulum is subjected to static forces in three directions, IA, OA, and PA, as follows: Figure 4 As shown, the formula for the maximum bending stress on a flexible beam is:

[0090] IA direction: ;

[0091] OA (Office Automation) direction: ;

[0092] PA direction: ;

[0093] Where F represents the load acting on the flexible beam (such as inertial force, impact load, etc.), and the unit is Newton; L represents the distance from the point of application of the load to the root of the flexible beam (corresponding to the effective length / lever arm of the beam), and the unit is millimeters. This indicates the width of the flexible beam, expressed in millimeters. This indicates the thickness of the flexible beam, expressed in millimeters. This represents the minimum cross-sectional area of ​​a flexible beam.

[0094] The sensitivity of these three parameters is analyzed below using the IA direction as an example. The width of the quartz pendulum flexible beam is varied from 3mm to 3.9mm, a change of 0.1mm, while other parameters remain unchanged. The stress changes are as follows: Figure 5 As shown, the width of the flexible beam has a linear relationship with the stress; when the thickness of the quartz pendulum flexible beam is varied from 0.01 mm to 0.1 mm (a change of 0.01 mm), while other parameters remain unchanged, the stress changes as follows. Figure 6 As shown, the thickness of the flexible beam has a power function relationship with the stress; when the distance from the root of the quartz pendulum flexible beam to the center of mass is changed from 7 mm to 7.9 mm (a change of 0.1 mm), while other parameters remain unchanged, the stress changes as follows. Figure 7As shown, the position of the centroid of the quartz pendulum is linearly related to the stress.

[0095] Therefore, it is evident that the thickness variation of the quartz pendulum flexible support structure has a dominant effect on stress, followed by the width, and finally the position of the center of mass. Thus, in the optimization design, the thickness of the flexible beam, the dominant parameter, should be optimized first, followed by adjusting the width and the distance from the beam root to the center of mass. This hierarchical structural optimization design aims to improve the vibration and impact resistance of the quartz pendulum.

[0096] The geometry of the flexible beam affects its strength, natural frequency, and reliability. By optimizing the main dimensional parameters of the flexible beam, its strength can be improved while maintaining its stiffness within a reasonable range. This ensures the accelerometer's sensitivity and, within the force balance control range, enhances the environmental adaptability of the quartz flexible accelerometer in drilling measurement-while-drilling applications. Detailed design steps are as follows:

[0097] By increasing the thickness of the flexible beam, its stress is reduced to less than 75% of the allowable stress of quartz material (67MPa), i.e., less than 50MPa, thereby reserving a safety margin of 25%.

[0098] Adjust the width of the flexible beam so that the stress it bears under maximum stress conditions does not exceed 75% of the allowable stress of the quartz material.

[0099] After adjusting the length of the flexible beam, calculate the swing distance of the flexible beam. Due to limitations such as the accelerometer range, scale factor, and torque current, the swing distance of the flexible beam is set to 1.3mm~1.6mm. When it exceeds this range, it will lead to problems such as reduced sensitivity of the accelerometer and instability of force feedback control.

[0100] Vibration simulation was performed using the finite element method. sinusoidal vibration and Random vibration simulation was used to determine the vibration response of the flexible beam and to check the maximum stress on the flexible beam in three directions.

[0101] Impact simulation was conducted. Since a single quartz pendulum component cannot withstand an impact of 1000g@0.5ms, the conditions for the half-sine impact simulation were initially set to [condition missing] during the component-level design and simulation phases. This makes it easier to determine whether the maximum stress in the three axes is within 50MPa. After determining the optimized dimensions, the same 1000g@0.5ms condition as the actual working condition will be used in the subsequent simulation of the sensitive unit component level.

[0102] To determine the optimal dimensions of the flexible beam, the combination of beam thickness, beam width, and beam length that maximizes the sway is selected as the optimal value, ensuring that the required dimensional parameters are met within the stress range.

[0103] The specific design parameters and effects of this application are as follows:

[0104] Assuming the flexible beam thickness is 0.02mm~0.05mm, the flexible beam width is 3.7mm~4.2mm, the maximum stress of the flexible beam does not exceed 50MPa, and the sway is taken as the maximum value in the range of 1.3mm~1.6mm, static simulation was performed on 97 sets of dimensions, and 45 sets of dimensions were selected for sinusoidal vibration, random vibration and impact simulation. Six sets of dimensions met the design requirements, as shown in Table 1. Finally, the optimal dimensions of the flexible beam were selected as 0.03mm thickness × 3.8mm width × 2.8mm length.

[0105] Table 1 Design Results of Quartz Pendulum Flexible Beam

[0106]

[0107] The simulation results of the maximum stress of the quartz pendulum before and after optimization were compared, such as... Figure 8 As shown, the results indicate that, in terms of static forces, the maximum stress in the IA direction of the optimized quartz pendulum flexible beam is reduced by 64.3% compared to the unoptimized direction. The IA direction corresponds to the motion direction of the accelerometer's working mode, so the reduction in maximum stress in this direction helps prevent the flexible beam from fracture. The stresses in the OA and PA directions are reduced by 53.7% and 34.5%, respectively. The stresses in these two directions were very small before optimization, and the static impact was almost negligible. In terms of sinusoidal vibration, although the maximum stress in the IA direction slightly increases to 44 MPa, it remains within the allowable stress range of quartz material, thus meeting the design requirements. The stresses in the OA and PA directions are reduced by 68.8% and 29.3%, respectively, indicating that the optimized structure has enhanced resistance to sinusoidal vibration. In terms of random vibration, the maximum stresses in all three directions of the optimized structure are reduced by 68.8%, 51.2%, and 29.4%, respectively, demonstrating a significant optimization effect for random vibration. In terms of impact, compared with the structure before optimization, the maximum stress in the IA direction is reduced by 18% after optimization, while the maximum stress in the OA direction is significantly reduced, with a 97.2% reduction. Although the stress in the PA direction is increased, its maximum stress value is only 0.52 MPa. Therefore, it meets the requirements of downhole measurement while drilling for quartz pendulums to resist strong vibrations and large impacts.

[0108] The comparison of the maximum stress before and after optimization of the dual isolation ring packaging structure under random vibration, sinusoidal vibration, and impact load is as follows: Figure 9As shown, the results indicate that the dual-isolation ring encapsulation scheme improves the maximum stress in all three axes of the quartz accelerometer under vibration and shock conditions. Under random vibration excitation, the maximum stress in the IA direction is significantly reduced from 62.7 MPa to 5.4 MPa, and under impact load excitation, the maximum stress is reduced from 142 MPa to 39.9 MPa. This demonstrates that the dual-isolation ring structure can enhance the vibration and shock resistance in the IA direction. Under random vibration and shock conditions, the maximum stress levels in both the OA and PA directions decreased significantly by orders of magnitude compared to before optimization. Under random vibration, the maximum stress in the OA direction decreased to 1 / 39 of that before optimization, and the maximum stress in the PA direction decreased to 1 / 60 of that before optimization. Under shock conditions, the maximum stress in the OA direction decreased from 1561.3 MPa to 31.4 MPa, which is 1 / 50 of that before optimization, and the maximum stress in the PA direction decreased from 2479.2 MPa to 46.7 MPa, which is 1 / 53 of that before optimization. This indicates that the optimized double-isolation ring encapsulation structure significantly improves the stress resistance of the quartz pendulum under extreme conditions, effectively solving the problem of easy damage to quartz flexible accelerometers under strong vibration and large impact.

[0109] A method for preparing a high-temperature resistant and highly stable magnetic steel component includes the following steps:

[0110] Raw materials are prepared according to the composition ratio of the magnet components, and alloy powder is prepared by ball milling: during the ball milling process, the average particle size of the alloy powder is controlled to be 4~5 micrometers. This particle size range ensures the uniformity and activity of the powder particles, while avoiding the risk of oxidation caused by excessively fine particles.

[0111] Drying the alloy powder removes residual moisture and impurities, preventing oxidation or compositional fluctuations caused by moisture in subsequent high-temperature processes, and ensuring material purity and performance consistency.

[0112] The dried alloy powder is oriented in a magnetic field: the strength of the orientation magnetic field is 2~3 Tesla. The orientation process makes the magnetocrystalline anisotropy direction of the alloy powder uniformly aligned along the direction of the magnetic field, which significantly improves the remanent magnetic induction intensity and magnetic energy product of the magnet. At the same time, it provides a structural basis for the magnetic stability at high temperature and ensures that the magnet after subsequent molding has a uniform magnetic field distribution.

[0113] The oriented alloy powder was sequentially pressed, sintered, and homogenized to obtain a green body: sintering was performed at 1200~1250℃ for 1~2 hours, followed by homogenization at 1150~1200℃ for 3 hours. At high temperatures, diffusion and metallurgical bonding occur between powder particles, gradually forming a dense polycrystalline structure, improving the density and mechanical strength of the green body. The sintered green body underwent homogenization at 1150~1200℃ for 3 hours to eliminate compositional segregation and microstructure inhomogeneity generated during sintering, ensuring uniform distribution of alloying elements within the grains, reducing internal stress, and providing a uniform microstructure basis for subsequent aging treatment.

[0114] The billet was aged to obtain the magnetic steel assembly: it was held at 860℃ for 11 hours, cooled to 450℃ at a rate of 0.5℃ / min, and held at 450℃ for 3.5 hours. During the aging process, fine and uniformly distributed second-phase particles precipitate inside the alloy, suppressing the irreversible movement of magnetic domains under high-temperature conditions, significantly improving the coercivity and temperature stability of the magnet, reducing the decay rate of magnetic properties with temperature changes, and especially greatly improving the performance of remanent magnetic induction intensity with temperature changes.

[0115] By controlling the powder particle size, orientation magnetic field strength, sintering temperature, homogenization treatment, and aging process, a magnetic steel component with high magnetic properties and excellent high-temperature stability is finally prepared, providing a stable and uniform working magnetic field for the quartz flexible accelerometer and ensuring the measurement accuracy and working reliability of the accelerometer under high-temperature and complex working conditions.

[0116] The magnetic properties of the magnets were tested to verify the improvement in their magnetic properties at different temperature points and ranges. The testing method involved setting the temperature range from room temperature to 200℃, with one temperature point tested at 20℃ intervals, for a total of 11 points. The comprehensive magnetic property test results of the magnets are shown in Tables 2 and 3.

[0117] Table 2. Magnetic Property Test Results of Magnets

[0118]

[0119] Table 3. Test results of temperature coefficient of magnetic properties of new magnetic steel.

[0120]

[0121] Test results show that by using the method of composite doping with three heavy rare earth elements, gadolinium (Gd), dysprosium (Dy), and erbium (Er), the temperature coefficient of remanent magnetic induction in the range of room temperature to 200℃ is significantly improved from -189ppm / ℃ to -103ppm / ℃, with a temperature performance improvement of 45.5%, compared with the magnetic steel with only Gd added.

[0122] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0123] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature resistant and highly stable quartz flexible accelerometer, comprising a housing (1), characterized in that, It also includes a sensitive unit (2) disposed inside the housing (1) and a buffer isolation structure (3) connected to the sensitive unit (2); The sensitive unit (2) is used to sense acceleration and output a corresponding signal. The sensitive unit (2) includes a quartz pendulum assembly and a magnet assembly for providing a magnetic field to the quartz pendulum assembly. The buffer isolation structure (3) is used to attenuate the mechanical vibration and impact energy transmitted from the outer shell (1) to the sensitive unit (2). The flexible beam structure parameters of the quartz pendulum assembly are optimized so that the maximum stress of the flexible beam is less than the allowable stress of the quartz material under preset static, vibration and impact loads, so that the swing amount of the quartz pendulum assembly is within the preset sensitivity range. The magnet assembly is made of samarium cobalt-based permanent magnet material, and the samarium cobalt-based permanent magnet material is composite doped with at least two heavy rare earth elements.

2. The high-temperature resistant and highly stable quartz flexible accelerometer according to claim 1, characterized in that, The buffer isolation structure (3) is a double isolation ring structure, which includes an inner isolation ring and an outer isolation ring coaxially sleeved.

3. The high-temperature resistant and highly stable quartz flexible accelerometer according to claim 1, characterized in that, The magnetic steel component is composed of Sm(1-x)HREx(Co) 0.7 Fe 0.2 Cu 0.08 Zr 0.02 )z; HRE represents heavy rare earth elements, and HRE includes gadolinium, dysprosium, and erbium; where 0 < x < 1, and z is a number between 7 and 8.

4. The high-temperature resistant and highly stable quartz flexible accelerometer according to claim 3, characterized in that, The specific component of the magnetic steel assembly is Sm 0.6 HRE 0.4 (Co 0.7 Fe 0.2 Cu 0.08 Zr 0.02 ) 7.2 ; Where HRE = Gd 0.87 Dy 0.065 Er 0.065 .

5. A high-temperature resistant and highly stable quartz flexible accelerometer according to claim 1, characterized in that, The thickness of the flexible beam is 0.02mm~0.05mm, the width of the flexible beam is 3.7mm~4.2mm, the maximum stress of the flexible beam does not exceed 50MPa, and the sway of the flexible beam is 1.3mm~1.6mm.

6. A design method for a high-temperature resistant and highly stable quartz flexible accelerometer, applied to the high-temperature resistant and highly stable quartz flexible accelerometer described in any one of claims 1 to 5, characterized in that, Includes the following steps: Determine the sensitivity of the structural parameters of the flexible beam to the stress of the flexible beam; wherein the structural parameters include at least the thickness, width and distance from the root of the beam to the centroid of the quartz pendulum. After determining the optimization order based on the impact sensitivity, the parameters of the flexible beam are adjusted; among them, the parameters that have the greatest impact on the stress of the flexible beam are optimized first. The stress state of the adjusted flexible beam under static, vibration and impact loads was verified through finite element simulation until the preset stress conditions were met and the optimal design parameters were achieved so that the swing of the quartz pendulum reached the predetermined target.

7. The design method of a high-temperature resistant and highly stable quartz flexible accelerometer according to claim 6, characterized in that, The optimization order is as follows: optimizing the thickness of the flexible beam, the width of the flexible beam, and the distance from the root of the beam to the centroid of the quartz pendulum.

8. The design method of a high-temperature resistant and highly stable quartz flexible accelerometer according to claim 7, characterized in that, The method for preparing the magnetic steel assembly includes the following steps: Raw materials were prepared according to the composition ratio of the magnet components, and alloy powder was prepared by ball milling. The alloy powder is dried. Orienting of dried alloy powder in a magnetic field; The oriented alloy powder is sequentially pressed, sintered, and homogenized to obtain a blank. The billet is subjected to aging treatment to obtain a magnetic steel assembly.

9. The design method of a high-temperature resistant and highly stable quartz flexible accelerometer according to claim 8, characterized in that, The average particle size of the alloy powder is controlled to be 4-5 micrometers; the strength of the orientation magnetic field is 2-3 Tesla.

10. The design method of a high-temperature resistant and highly stable quartz flexible accelerometer according to claim 8, characterized in that, Sintering is carried out at 1200~1250℃ for 1~2 hours, followed by homogenization treatment at 1150~1200℃ for 3 hours; The aging process involves holding the temperature at 860℃ for 11 hours, then cooling it to 450℃ at a rate of 0.5℃ / minute, and holding it at 450℃ for 3.5 hours.

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