Quartz flexible accelerometer pendulum assembly capable of reducing coil thermal strain

Abstract

The invention belongs to the technical field of accelerometers, and provides a quartz flexible accelerometer pendulum assembly capable of reducing coil thermal strain, which comprises a quartz pendulum sheet and a coil skeleton, the coil skeleton is in the shape of a circumferentially symmetrical cylinder, and an expansion joint is arranged on a pendulum tongue of the quartz pendulum sheet. The coil framework structure is designed into a cylindrical shape with symmetrical circumference, so that the constraint of the original coil framework base on the deformation of the winding is avoided, and meanwhile, the cylindricity of the winding in a high-temperature environment is effectively improved. The expansion joint is arranged on the pendulum tongue of the quartz pendulum sheet, so that the thermal stress of the winding can be reduced, and the constraint on the winding is further relaxed. The simulation design verifies that the stability of the coil structure is improved, the scale factor temperature coefficient generated by the thermal strain of the coil can be reduced, and the quartz flexible accelerometer pendulum assembly has important engineering application value for improving the temperature adaptability of a quartz flexible accelerometer.

Description

Technical Field

[0001] The invention belongs to the technical field of accelerometers, and in particular relates to a quartz flexible accelerometer pendulum component for reducing coil thermal strain. Background Art

[0002] Quartz flexible accelerometers are key components in modern inertial navigation systems and are widely used in space navigation, inertial navigation, and ground motion control. In the exploration of oil and coal mines, complex geological conditions and extreme temperature environments are often encountered. In actual downhole exploration measurements, accelerometers must have the ability to maintain feedback stability in high temperature environments for a long time. Quartz flexible accelerometers are typical torque balance sensors that balance the inertial force of the sensitive mass through the Ampere force generated by the coil winding in a stable magnetic field and perform detection and control. Therefore, the coil winding is one of the keys to ensure the feedback temperature stability of the quartz accelerometer system.

[0003] The existing coil is composed of a copper wire winding wound on an aluminum alloy frame, and then bonded to a quartz pendulum piece by epoxy glue to form a pendulum assembly. The bonding surface is generally considered to be a binding contact, that is, there is a binding contact constraint relationship between quartz and epoxy glue, epoxy glue and aluminum alloy, and aluminum alloy and copper wire. Due to the different thermal expansion coefficients of several mutually constrained materials, thermal stress is generated. In a high temperature environment, the thermal strain generated by the coil causes the winding part of the structure to expand, causing the position of the current in the stable magnetic field to change, and ultimately causing the magnitude and point of action of the feedback force to change. Therefore, the thermal strain of the coil winding in a high temperature environment will cause the temperature coefficient of the scale factor of the quartz flexible accelerometer to change, affecting the temperature stability of the scale factor of the accelerometer.

[0004] In summary, the winding needs to be able to generate stable feedback force in a variable temperature environment, and thermal strain analysis and pendulum assembly structural design are required to improve the temperature stability of the coil structure. However, the existing technology lacks analysis of the thermal strain of the quartz accelerometer winding; it is necessary to optimize the pendulum assembly structure, reduce the thermal strain of the winding, and reduce the temperature coefficient of the accelerometer scale factor caused by thermal strain, so that it meets the application conditions of high-temperature wells and improves the temperature adaptability of the quartz flexible accelerometer. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention proposes a quartz flexible accelerometer pendulum assembly for reducing the thermal strain of the coil, which improves the structure of the existing quartz flexible accelerometer by changing the structure of the winding coil and designing expansion joints on the pendulum piece to relax the constraints on the winding and reduce the thermal strain of the coil, thereby effectively improving the temperature adaptability of the quartz flexible accelerometer.

[0006] The technical solution of the present invention is as follows:

[0007] A quartz flexible accelerometer pendulum assembly for reducing coil thermal strain comprises a quartz pendulum piece and a coil frame. The coil frame is in a circumferentially symmetrical cylindrical shape. An expansion joint is provided on the pendulum tongue of the quartz pendulum piece.

[0008] Preferably, the expansion joint is arranged at the bonding position between the coil frame and the swing tongue, and a bonding portion and a supporting portion are formed in the expansion joint.

[0009] Preferably, the expansion joints are bean sprout-shaped or S-shaped, the number of the expansion joints is 4, and they are distributed in a biaxially symmetrical manner.

[0010] Preferably, the tail of the expansion joint extends toward the center of the quartz pendulum, and the center of the inner diameter of the extension section is on the radius of the pendulum.

[0011] Preferably, the expansion joint can isolate the mutual influence between the capacitor plate and the bonding point between the coil frame and the quartz pendulum.

[0012] Preferably, the coil skeleton and the swing tongue have a total of 4 bonding parts, which are distributed in a biaxial symmetrical manner, each of which is not less than 1 mm in length and 5 mm in width. The angle between the distribution on the circumference and the transverse axis of symmetry is 15°-30°, and the width of the expansion joint is 0.2 mm, of which the width between the bonding part and the supporting part is 0.2-0.8 mm. The tail of the expansion joint extends toward the center of the quartz swing piece, and the center of the inner diameter of the extended section is on the radius of the swing piece. The radius length is 0.5 mm, and the angle between the normal diameter and the transverse axis of symmetry is 60° to reduce concentrated stress.

[0013] Preferably, the inner diameter of the coil skeleton is 9.8 mm, the side wall thickness is 0.1 mm, the flange wall thickness on the side bonded to the quartz pendulum is 0.22 mm, and the limiting flange wall thickness on the other side is 0.15 mm.

[0014] Preferably, the coil skeleton is made of aluminum alloy.

[0015] A structural design method for a quartz flexible accelerometer pendulum assembly comprises the following steps:

[0016] Step S1: establishing a thermal field-structure-magnetic field multi-physics field simulation model of a quartz flexible accelerometer pendulum assembly;

[0017] Step S2: setting the design parameters of the quartz flexible accelerometer pendulum assembly, wherein the design parameters include the shape, position and size of the coil skeleton, the quartz pendulum piece and the expansion joint;

[0018] Step S3: Based on the thermal field-structure-magnetic field multi-physics field simulation model, simulate and calculate the thermal strain of the coil and the change of the magnetic field force under the temperature impact of a typical working environment;

[0019] Step S4: Analyze the simulation results and return to step S2 to optimize the design parameters of the quartz flexible accelerometer pendulum assembly.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The quartz flexible accelerometer pendulum assembly for reducing coil thermal strain of the present invention adopts a circumferentially symmetrical cylindrical coil skeleton structure, which avoids the constraint of the original coil skeleton base on the winding deformation and effectively improves the cylindricity of the winding in a high temperature environment.

[0022] 2. The quartz flexible accelerometer pendulum assembly for reducing the thermal strain of the coil of the present invention is provided with an expansion joint on the pendulum tongue of the quartz pendulum piece, which can reduce the thermal stress of the winding and further relax the constraints on the winding.

[0023] 3. The quartz flexible accelerometer pendulum assembly for reducing coil thermal strain of the present invention has been verified by simulation design to improve the stability of the coil structure and reduce the temperature coefficient of the scale factor caused by the coil thermal strain, which has important engineering application value for improving the temperature adaptability of the quartz flexible accelerometer.

[0024] 4. The multi-physics field simulation model of the quartz flexible accelerometer head established by the present invention integrates mechanical calculation, temperature calculation, and magnetic field calculation, and can effectively calculate the thermal strain of the winding, and transfer the winding deformation to the magnetic field to calculate the change of the magnetic field force. The traditional formula calculation is difficult to simulate the complex pendulum structure of the accelerometer. The simulation model is simple to establish, the calculation structure is accurate, the calculation time is saved, and the experimental efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the drawings. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 The figure is a schematic structural diagram of a quartz flexible accelerometer pendulum assembly for reducing coil thermal strain according to the present invention.

[0027] Figure 2 Schematic diagram of the thermal field-structure-magnetic field multi-physics field simulation model structure of the quartz flexible accelerometer pendulum assembly.

[0028] Figure 3 This is a connection diagram of the thermal field-structure-magnetic field multi-physics field simulation model.

[0029] Figure 4This is a schematic diagram of the structure of the Ф25.4 type quartz flexible accelerometer movement.

[0030] Figure 5 This is the mesh division result of the Ф25.4 type quartz flexible accelerometer core.

[0031] Figure 6 Schematic diagram of setting boundary conditions for a thermal-structural-magnetic multiphysics simulation model.

[0032] Figure 7 The present invention is a schematic diagram of the structure of the coil skeleton and the quartz pendulum piece in the quartz flexible accelerometer pendulum assembly for reducing the thermal strain of the coil.

[0033] Figure 8 The temperature distribution and thermal strain simulation results of the original structure pendulum components.

[0034] Fig. 9 These are the simulation results of thermal strain and thermal stress of the coil and coil frame in the original structure pendulum assembly.

[0035] Fig.10 The simulation results of the coil magnetic field force of the original structural components.

[0036] Fig.11 To optimize the temperature distribution and thermal strain simulation results of the structural pendulum components.

[0037] Fig.12 To optimize the simulation results of thermal strain and thermal stress of coils and coil frames in structural pendulum components.

[0038] Fig.13 Simulation results of coil magnetic field force simulation for optimizing structural pendulum assembly. DETAILED DESCRIPTION

[0039] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0041] The quartz flexible accelerometer pendulum assembly structure for reducing coil thermal strain proposed by the present invention is as follows: Figure 1 In order to verify the effectiveness of the quartz flexible accelerometer pendulum assembly for reducing coil thermal strain proposed by the present invention, the following simulation verification experiment was conducted.

[0042] Example 1

[0043] Step 1: Establish a thermal field-structure-magnetic field multi-physics field simulation model of the quartz flexible accelerometer pendulum assembly to provide a calculation basis for comparative simulation.

[0044] The thermal strain simulation model of the quartz flexible accelerometer head assembly is established using ANSYS WORKBENCH software to simulate the heat transfer, strain and magnetic changes of the parts in a high temperature environment for a long time. Figure 2 The data transmission of the simulation model in the software is as follows Figure 3 The specific steps are as follows:

[0045] (1) Importing geometric models and meshing

[0046] This embodiment takes a 25.4-inch quartz flexible accelerometer as an example, and simplifies the parts and structures in the movement that are not important for the simulation results to increase the calculation speed. The simplified model structure is as follows: Figure 4 The mesh division results are shown in Figure 5 shown.

[0047] (2) Define material parameters

[0048] The material property definitions of the various parts of the quartz accelerometer movement are shown in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] (3) Define boundary conditions and solve

[0053] The coil heat source intensity is defined according to the scale factor setting. To simulate the closed environment inside the watch movement, the air convection heat transfer coefficient is set to 5W / (m 2 ·K). Set the steady-state ambient temperature. Add the outer ring boss fixed constraint of the pendulum assembly in the stress simulation. Set the accelerometer excitation. The boundary condition settings are as follows: Figure 6 shown.

[0054] (4) Post-processing of simulation results

[0055] The simulation model can derive structural temperature change results, thermal strain results, thermal stress results, air gap magnetic induction intensity distribution, and coil Ampere force magnitude.

[0056] Step 2: Remove the bonding base of the coil frame and optimize the coil frame structure to a cylindrical shape.

[0057] The existing coil frame base constrains the deformation of the winding and also generates greater stress. In addition, the welding holes reserved in the coil frame base make the force on the winding not symmetrical. In order to reduce the thermal strain of the winding, the coil frame structure is designed to be cylindrical, such as Figure 7 As shown in (a), the optimized coil frame structure is circumferentially symmetrical, which can improve the cylindricality of the winding in a high temperature environment.

[0058] The dimensions of the frame are: inner diameter 9.8mm, side wall thickness 0.1mm, flange wall thickness on the side bonded to the swing plate 0.22mm, and the limit flange wall thickness on the other side 0.15mm. The frame is made of aluminum alloy.

[0059] Step 3: Design expansion joints on the quartz pendulum to further release the constraints on the winding fixation.

[0060] The swing tongue is a nearly semicircular glass sheet, and the winding is bonded to the swing tongue through the base. The quartz material near the center of the circle is constrained by the surrounding materials and is not easily deformed, which further increases the constraint force of the winding. In order to reduce the thermal stress of the winding and relax the constraint on the winding, an S-shaped expansion joint is designed at the bonding position, such as Figure 7 As shown in (b), the expansion joint on the swing tongue can reduce the thermal stress of the winding.

[0061] The S-shaped expansion joint is distributed in a biaxial symmetric manner. In this embodiment, the length of the bonding part is 1.2mm and the width is 5mm. There are 4 bonding points on the circumference, which are distributed in a biaxial symmetric manner. The angles between the upper and lower bonding parts and the transverse symmetry axis are 15° and 30° respectively. Except for the gap between the bonding part and the supporting part of the S-shaped expansion joint, which is 0.7mm, the rest of the gaps are 0.2mm. The tail of the S-shaped expansion joint extends to the center of the swing plate, and the center of the inner diameter of the extension section is on the radius of the swing plate. The radius length is 0.5mm, and the angle between the normal diameter and the transverse symmetry axis is 60°.

[0062] Step 4: Compare and verify based on the thermal field-structure-magnetic field multi-physics field simulation model of the quartz flexible accelerometer pendulum assembly:

[0063] Based on the multi-physics field model, the thermal strain and magnetic force changes of the original structure and the optimized structure under 1g acceleration excitation at an ambient temperature of 150℃ are simulated and calculated respectively.

[0064] The simulation results of the original structure are as follows:

[0065] (1) Figure 8As shown, (a) is the temperature distribution of the pendulum assembly, and (b) is the thermal deformation. It can be seen that the temperature rise of the coil, coil frame and pendulum tongue is 1.29°C in steady state. The temperature distribution on the pendulum tongue is relatively uniform, and the temperature on the pendulum beam gradually decreases from the inside to the outside. Since the thermal conductivity of quartz and epoxy glue is small, and the coil is installed inside the watch movement, the coil lacks a heat dissipation channel and it is difficult to transfer heat to the outside. Therefore, the deformation of the coil caused by heat cannot be ignored.

[0066] (2) Steady-state thermal deformation and stress of coil and coil frame Fig. 9 As shown. Among them, (a) is the coil strain, (b) is the coil stress, (c) is the coil skeleton strain, and (d) is the coil skeleton stress. Since the coil skeleton base has a certain supporting and fixing effect, the strain of the coil close to the base is small and the stress is large. Since the coil skeleton base needs to reserve welding points, the coil skeleton is not circumferentially symmetrical, so the coil does not expand uniformly along the circumference, and the maximum deformation occurs on the same side of the welding point. The nodes with larger coil deformation are distributed nearly half of the circumference, and the average displacement of the nodes is 15.5um. The maximum stress of the coil skeleton occurs near the bonding point with the swing tongue, and the maximum deformation occurs on the entire outer circle edge.

[0067] (3) Fig.10 As shown, (a) is the magnetic field force before the coil is thermally deformed, and (b) is the magnetic field force after the coil is thermally deformed. The coil expands outward, making the current conductor closer to the outer diameter area, reducing the electromagnetic force. The coil force is set to parameter export, the resultant force before deformation is 8.565mN, and the resultant force after thermal deformation is 8.531mN. It can be seen that in a high temperature environment of 150℃, the scale factor of this type of quartz accelerometer is reduced by 3969ppm due to the thermal strain of the coil, that is, the temperature coefficient of the scale factor caused by the thermal strain of the coil is 26.5ppm / ℃.

[0068] The optimized structure simulation results are as follows:

[0069] (1) Fig.11 As shown, (a) is the temperature distribution of the pendulum assembly, and (b) is the thermal deformation. It can be seen that under the same ambient temperature, the temperature rise of the coil is 1.47°C. And the existence of the expansion joint reduces the heat dissipation of the coil to the pendulum.

[0070] (2) Steady-state thermal deformation and stress of the coil and coil frame, such as Fig.12As shown. Among them, (a) is the coil strain, (b) is the coil stress, (c) is the coil skeleton strain, and (d) is the coil skeleton stress. It can be seen that the optimized coil skeleton is symmetrical about the circular axis, so that the coil is subjected to a more uniform force, and the cylindricality after thermal deformation is greatly improved. The nodes with large displacements between the coil and the coil skeleton only appear on the axis of symmetry, and the average displacement of the coil nodes is reduced to 13.3um, which is 14% less than the original structure. The maximum stresses of the coil and the coil skeleton are reduced by 22.4MPa and 65.1MPa respectively compared with the original structure, which are reduced by 20.2% and 41.9% respectively.

[0071] (3) Coil magnetic force simulation comparison Fig.13 As shown, (a) is the magnetic field force before the coil is thermally deformed, and (b) is the magnetic field force after the coil is thermally deformed. The resultant force before the coil is deformed is 7.427mN, and the resultant force after the coil is thermally deformed is 7.411mN. In a 150℃ environment, the scale factor of this type of accelerometer is reduced by 2114ppm due to the thermal strain of the coil, that is, the temperature coefficient of the scale factor caused by the thermal strain of the coil is 14.1ppm / ℃.

[0072] The comparison of simulation results between the original structure and the optimized structure is shown in Table 2.

[0073] Table 2

[0074] Original structure Optimize structure Average displacement of coil nodes / μm 15.5 13.3 Magnetic force change / μN 34.2 15.7 <![CDATA[Scale factor temperature coefficient / ppm·°C -1 > 26.5 14.1

[0075] In summary, the average coil deformation of the quartz flexible accelerometer pendulum assembly proposed by the present invention is reduced by 14% under a high temperature environment of 150°C, and the temperature coefficient of the scale factor caused by the thermal strain of the coil is reduced by 47%. It is effectively verified that it can effectively reduce the high temperature thermal strain of the coil, improve the magnetic temperature stability, and improve the temperature performance of the scale factor of the quartz accelerometer, which has important engineering application value for improving the temperature adaptability of the quartz flexible accelerometer.

[0076] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0078] In the present invention, the terms "first", "second", "third", "fourth" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The term "plurality" refers to two or more, unless otherwise clearly defined.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A quartz flexible accelerometer pendulum assembly for reducing coil thermal strain, comprising a quartz pendulum piece and a coil frame, characterized in that: The coil frame is in the shape of a cylinder with circumferential symmetry, and an expansion joint is arranged on the swing tongue of the quartz swing piece.

2. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The expansion joint is arranged at the bonding position between the coil frame and the swing tongue, and a bonding part and a supporting part are formed in the expansion joint.

3. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The expansion joints are in a bean sprout shape or an S shape, are 4 in number, and are distributed in a biaxially symmetrical manner.

4. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The tail of the expansion joint extends toward the center of the quartz pendulum, and the center of the inner diameter of the extension section is on the radius of the pendulum.

5. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The expansion joint can isolate the mutual influence between the capacitor plate and the coil frame and the bonding part of the quartz pendulum.

6. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The coil skeleton and the swing tongue have a total of 4 bonding parts, which are distributed in a biaxial symmetrical manner. The length of each part is not less than 1mm and the width is 5mm. The angle between the distribution on the circumference and the transverse symmetry axis is 15°-30°, and the width of the expansion joint is 0.2mm, of which the width between the bonding part and the supporting part is 0.2-0.8mm. The tail of the expansion joint extends to the center of the quartz swing piece, and the center of the inner diameter of the extended section is on the radius of the swing piece. The radius length is 0.5mm, and the angle between the normal diameter and the transverse symmetry axis is 60° to reduce concentrated stress.

7. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The inner diameter of the coil skeleton is 9.8 mm, the side wall thickness is 0.1 mm, the flange wall thickness on the side bonded to the quartz pendulum is 0.22 mm, and the limiting flange wall thickness on the other side is 0.15 mm.

8. The quartz flexible accelerometer pendulum assembly according to claim 1, characterized in that: The coil frame is made of aluminum alloy.

9. A structural design method for a quartz flexible accelerometer pendulum assembly as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1: establishing a thermal field-structure-magnetic field multi-physics field simulation model of a quartz flexible accelerometer pendulum assembly; Step S2: setting the design parameters of the quartz flexible accelerometer pendulum assembly, wherein the design parameters include the shape, position and size of the coil skeleton, the quartz pendulum piece and the expansion joint; Step S3: Based on the thermal field-structure-magnetic field multi-physics field simulation model, simulate and calculate the thermal strain of the coil and the change of the magnetic field force under the temperature impact of a typical working environment; Step S4: Analyze the simulation results and return to step S2 to optimize the design parameters of the quartz flexible accelerometer pendulum assembly.

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