Design method of moving coil detector movement

Abstract

The invention provides a method for designing a movement of a moving-coil detector, which belongs to the field of passive magnetoelectric sensors and comprises the following steps of: analyzing a plurality of influence parameters influencing the sensitivity of the moving-coil detector according to the relationship between an electromechanical coupling coefficient and the sensitivity of the moving-coil detector; analyzing key parameters for regulating and controlling the size of the eddy current in the plurality of influence parameters through the relationship between the electromechanical coupling coefficient of the moving-coil detector and the eddy current damping factor; optimizing the structure of the moving coil detector core according to the key parameters to obtain an inner magnetic circuit assembly comprising a main magnetic circuit and an auxiliary magnetic circuit; the magnetic field intensity and the eddy current damping factor of the moving-coil detector are respectively adjusted through the main magnetic circuit and the auxiliary magnetic circuit, and the moving-coil detector core with high sensitivity and low damping is obtained. The design method is a brand new design concept, the situation that the eddy current damping factor of the moving-coil detector cannot be regulated and controlled can be broken through, and the moving-coil detector movement designed through the design method breaks through the index upper limit of the sensitivity of the new national standard for the first time.

Description

Technical Field

[0001] The present invention belongs to the field of passive magnetoelectric sensors, and particularly relates to a design method for a moving coil geophone core unit. Background Art

[0002] The five technical indicators of a moving coil geophone are: internal resistance R (Ω), frequency (Hz), damping factor h (%), sensitivity a (v / m / s), and distortion (‰). Currently, the best commercially available and miniaturized moving coil geophone core units at home and abroad have the following five technical indicators: R: 1850 (Ω), f: 5 (Hz), h: 50 - 70 (%), a: 80 (v / m / s), ≤2‰. According to the new national standard (effective from October 1, 2022), the upper limit of sensitivity is 150 v / m / s.

[0003] In summary, the sensitivity of the best current moving coil geophone core units at home and abroad can only reach 53% of the upper limit of the sensitivity in the new national standard (80 / 150 ≈ 53%). Such a large gap poses a huge challenge to designers. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a design method for a moving coil geophone core unit, which specifically includes the following steps:

[0005] Analyze multiple influencing parameters that affect the sensitivity of the moving coil geophone through the relationship between the electromechanical coupling coefficient and the sensitivity of the moving coil geophone;

[0006] Analyze the key parameters that control the eddy current magnitude among the multiple influencing parameters through the relationship between the electromechanical coupling coefficient and the eddy current damping factor of the moving coil geophone;

[0007] Optimize the structure of the moving coil geophone core unit according to the key parameters to obtain an inner magnetic circuit component including a main magnetic circuit and an auxiliary magnetic circuit;

[0008] Adjust the magnetic field intensity and the eddy current damping factor of the moving coil geophone through the main magnetic circuit and the auxiliary magnetic circuit respectively to obtain a moving coil geophone core unit that meets the sensitivity requirements.

[0009] Preferably, the multiple influencing parameters include the number of turns of the coil, the gap field strength, the magnetic conduction width, the resistivity, the wall thickness of the metal wire frame, the height of the metal wire frame, and the properties of the material.

[0010] Preferably, the key parameters that control the eddy current magnitude are the wall thickness of the metal wire frame, the height of the metal wire frame, and the properties of the material.

[0011] Preferably, the calculation formula for the electromechanical coupling coefficient is:

[0012]

[0013] Wherein, W is the number of turns of the winding, is the magnetic current gradient.

[0014] Preferably, the calculation formula of the sensitivity is:

[0015]

[0016] Wherein, G is the electromechanical coupling coefficient, R1 is the internal resistance of the movement core, and R2 is the parallel shunt resistance.

[0017] Preferably, the calculation formula of the eddy current damping factor is:

[0018]

[0019] Wherein, H is the gap field strength, G is the electromechanical coupling coefficient, b is the magnetic permeability width of the yoke, δ1 is the wall thickness of the metal wire frame, ρ* is the resistivity, and W is the number of turns of the winding.

[0020] Preferably, the inner magnetic circuit assembly is axially arranged inside the housing of the moving coil geophone movement, and the axial ends of the inner magnetic circuit assembly are clamped with the two ends of the housing of the moving coil geophone movement.

[0021] Preferably, the main magnetic field strength is adjusted by the magnetic field generated by the bipolar opposite magnetic steel and the corresponding magnetic permeability width.

[0022] Preferably, the auxiliary magnetic circuit adjusts the turbine damping factor by setting an eddy current ring with adjustable magnetic permeability width.

[0023] The design method of the moving coil geophone movement provided by the present invention has the following beneficial effects:

[0024] Through the relationship between the electromechanical coupling coefficient and the sensitivity of the moving coil geophone of the present invention, multiple influencing parameters affecting the sensitivity of the moving coil geophone can be analyzed; through the relationship between the electromechanical coupling coefficient and the eddy current damping factor, the key parameters for regulating the eddy current size among the multiple influencing parameters can be analyzed, and the eddy current damping factor can be regulated according to the key parameters, thereby optimizing the structure of the moving coil geophone; the sensitivity of the optimized moving coil geophone is greatly improved, and its sensitivity has exceeded the upper limit value (150 v / m / s) of the new national standard sensitivity. The present invention realizes the adjustable and controllable technology of the eddy current damping factor of the moving coil geophone for the first time in design, and the moving coil geophone movement designed by the design method of the present invention breaks through the upper limit of the index of the new national standard sensitivity a for the first time. Description of the Drawings

[0025] To more clearly illustrate the embodiments of the present invention and their design schemes, the accompanying drawings required for this embodiment will be briefly introduced below. The accompanying drawings in the following description are only partial embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0026] Figure 1 It is a flowchart of the design method of the moving coil geophone core for the embodiment of the present invention. Specific embodiments

[0027] In order to enable those skilled in the art to better understand the technical solutions of the present invention and implement them, the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0029] In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified or limited, the terms "connected" and "connected" 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 directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In the description of the present invention, unless otherwise stated, the meaning of "plurality" is two or more, which will not be elaborated here.

[0030] Embodiment

[0031] The present invention provides a design method for a moving coil geophone core, specifically as Figure 1 shown, including the following steps:

[0032] Step 1: Analyze multiple influencing parameters that affect the sensitivity of the moving coil geophone through the relationship between the electromechanical coupling coefficient and the sensitivity of the moving coil geophone.

[0033] The calculation formula for the electromechanical coupling coefficient of a moving coil geophone is as follows:

[0034]

[0035] Where W is the number of turns of the coil, is the magnetic current gradient.

[0036] The calculation formula for sensitivity is as follows:

[0037]

[0038] Where G is the electromechanical coupling coefficient, R1 is the internal resistance of the movement, and R2 is the parallel shunt resistance.

[0039] It can be seen from equations (1) and (2) that when R₂ → ∞, a ≈ G, that is, when the movement of the moving coil geophone is open-circuited, its sensitivity a is approximately equal to the electromechanical coupling coefficient G. Therefore, the sensitivity a can be used to replace the electromechanical coupling coefficient G during calculation. Therefore, the parameters affecting sensitivity include the number of turns of the coil W, the magnetic current gradient the internal resistance R1 of the movement, and the parallel shunt resistance R2.

[0040] Step 2: Analyze the key parameters for regulating the eddy current magnitude among multiple influencing parameters through the relationship between the electromechanical coupling coefficient and the eddy current damping factor of the moving coil geophone.

[0041] The multiple influencing parameters include the number of turns of the coil, the gap field strength, the magnetic conduction width, the resistivity, and the wall thickness of the metal wire frame. The key parameters for regulating the eddy current magnitude among the influencing parameters are analyzed below through the calculation formula for the eddy current damping factor.

[0042] The calculation formula for the eddy current damping factor is as follows:

[0043]

[0044] Where H is the gap field strength, G is the electromechanical coupling coefficient, b is the magnetic conduction width of the yoke iron, δ1 is the wall thickness of the metal wire frame, ρ* is the resistivity, and W is the number of turns of the coil.

[0045] It can be seen from equation (1) that there are two effective ways to improve sensitivity. One is to directly increase the number of turns of the coil W, but this will be accompanied by a sharp increase in the internal resistance R1 of the movement. The increase in the internal resistance R1 of the movement will cause an increase in the self-load of the geophone, an increase in volume, and a sharp decrease in its transmission load-carrying capacity and anti-interference ability. The other is to increase its magnetic current gradient At the same time, the gap field strength H also increases accordingly.

[0046] According to the eddy current damping factor formula (3), when it is necessary to reduce the eddy current damping factor, the denominator of formula (3) needs to be increased and the numerator decreased. However, in the numerator, when the sensitivity a increases, that is, the electromechanical coupling coefficient G increases, the gap field strength H also increases, and the thickness reduction of the metal wire frame wall δ1 is limited. If the magnetic permeability width b of the yoke becomes narrower, it is likely to cause magnetic field instability and is not conducive to forming a stable uniform magnetic field. Therefore, the eddy current damping factor cannot be reduced by decreasing the numerator. In the denominator, the resistivity ρ* is a fixed value, and when the number of turns W of the coil increases, the internal resistance R1 will increase. Therefore, the eddy current damping factor cannot be reduced by increasing the denominator.

[0047] In addition, there is also the electromagnetic damping factor formula:

[0048] In the formula, G is the mechanical coupling coefficient, approximately equal to the sensitivity a, f is the natural frequency, m is the mass of the inertial body, R2 is the parallel shunt resistance, and R1 is the internal resistance of the movement.

[0049] It can be seen from formula (4) that the electromagnetic damping factor h1 is proportional to the square of the sensitivity a. Although h1 is inversely proportional to the frequency f, the frequency f cannot be designed too large because when the natural frequency f is large, the low-end frequency band will become narrower, resulting in the loss of low-frequency information. The inertial body m cannot be too heavy either, because being too heavy will cause the anti-drop ability of the movement to decrease sharply. The size of the parallel shunt resistance R2 is limited by the input resistance of the seismograph and cannot be too large either. The internal resistance R1 of the movement cannot be too large either. Therefore, the size of the electromagnetic damping factor h1 will mainly be determined by the size of the sensitivity a. Then, according to the total damping factor formula, it can be known that: h = h1 + h2 - (5). When both h1 and h2 increase, h will necessarily increase sharply. At this time, the geophone core will show a serious over-damping state, which will greatly suppress the low-frequency signal response ability of the geophone, and at the same time, the receiving ability will become sluggish, and the geophone tester will also be out of range and unable to perform normal detection. This is the reason why the sensitivity of small-sized moving coil geophones at home and abroad has stagnated at 80 (v / m / s)!

[0050] In summary, the key parameters for regulating the eddy current size are the wall thickness of the metal wire frame, the height of the metal wire frame, and the properties of the material.

[0051] Step 3: Optimize the structure of the moving coil geophone core according to the key parameters to obtain an internal magnetic circuit component including a main magnetic circuit and an auxiliary magnetic circuit;

[0052] The inner magnetic circuit component of the moving coil geophone core is axially arranged inside the housing of the moving coil geophone core. The axial ends of the inner magnetic circuit component are clamped to both ends of the housing of the moving coil geophone core. The present invention takes the magnetic conduction width b of the yoke as a breakthrough point and improves the material of the metal wire frame into a form of combination of metal and non-metal. Among them, the coil skeleton is designed as a non-metal frame, and the non-metal coil skeleton does not generate an eddy current damping factor. Then, a metal eddy current ring is arranged on the coil skeleton, and the turbine ring does not participate in winding the wire coil. Since the size of the eddy current ring is adjustable, its magnetic conduction width b x (that is, the height of the corresponding part of the eddy current ring and the yoke) can be adjusted according to needs. Therefore, the formula of the eddy current damping factor becomes In addition, in order to greatly improve the sensitivity a, the inner magnetic circuit is designed into a main magnetic circuit and an auxiliary magnetic circuit. The main magnetic circuit adopts a bipolar opposite combination magnet and has a wide magnetic conduction width b1 of the yoke, thus laying a good foundation for increasing the strong uniform magnetic field gap H and forming a necessary magnetic field condition for obtaining a high sensitivity a.

[0053] Step 4: Respectively adjust the magnetic field strength and the eddy current damping factor of the moving coil geophone through the main magnetic circuit and the auxiliary magnetic circuit to obtain a moving coil geophone core with high sensitivity and low damping, which meets the international quality requirements.

[0054] The main magnetic circuit of the present invention adjusts the magnetic field strength through the magnetic field generated by the bipolar opposite combination magnet and the first magnetic conduction width. The auxiliary magnetic circuit adjusts the turbine damping factor by setting an eddy current ring with adjustable magnetic conduction width. So far, the situation that the eddy current damping factor of the moving coil geophone cannot be adjusted and controlled in the design will be broken! And this new structural mode of adjusting the eddy current damping factor h2 can not only meet the two-magnet and three-wire coil combination system, but also meet the three-magnet and four-wire coil combination system and more magnet and wire coil combination systems.

[0055] As can be seen from the above description, the moving coil geophone core designed by this method has a relatively high sensitivity a, which has exceeded the upper limit value of 150 v / m / s of the new national standard sensitivity; the present invention has realized the adjustable and controllable technology of the eddy current damping factor h2 of the moving coil geophone for the first time in design; and it is the first miniaturized, high-sensitivity and low-internal-resistance moving coil geophone core at home and abroad. Among the moving coil geophone cores with comparable sensitivity and internal resistance, it has the smallest volume, realizes the built-in matching mode with various node seismographs, improves the field construction efficiency and reduces the construction labor intensity; reduces the material use and reduces the manufacturing cost of the core.

[0056] The above embodiments are only preferred specific embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope disclosed by the present invention all belong to the protection scope of the present invention.

Claims

1. A design method for a moving coil geophone core, characterized in that, The steps are as follows: Analyze multiple influencing parameters that affect the sensitivity of the moving coil geophone through the relationship between the electromechanical coupling coefficient and the sensitivity of the moving coil geophone; Analyze the key parameters that regulate the eddy current magnitude among the multiple influencing parameters through the relationship between the electromechanical coupling coefficient and the eddy current damping factor of the moving coil geophone; Optimize the structure of the moving coil geophone core according to the key parameters to obtain an inner magnetic circuit component including a main magnetic circuit and an auxiliary magnetic circuit; Adjust the magnetic field strength and the eddy current damping factor of the moving coil geophone through the main magnetic circuit and the auxiliary magnetic circuit respectively to obtain a moving coil geophone core that meets the sensitivity requirements.

2. The design method of the moving coil geophone core according to claim 1, characterized in that, The multiple influencing parameters include the number of turns of the coil, the gap field strength, the magnetic conduction width, the resistivity, the wall thickness of the metal wire frame, the height of the metal wire frame, and the properties of the material.

3. The design method of the moving coil geophone core according to claim 2, characterized in that The key parameters for regulating the eddy current magnitude are the wall thickness of the metal wire frame, the height of the metal wire frame, and the properties of the material.

4. The design method of the moving coil geophone core according to claim 1, characterized in that The calculation formula for the electromechanical coupling coefficient is: where W is the number of turns of the winding, is the magnetic current gradient.

5. The design method of the moving coil geophone core according to claim 1, characterized in that, The calculation formula for the sensitivity is: In the formula, G is the electromechanical coupling coefficient, R1 is the internal resistance of the core, and R2 is the shunt resistance in parallel.

6. The design method of the moving coil geophone core according to claim 1, characterized in that, The calculation formula for the eddy current damping factor is: In the formula, H is the gap field strength, G is the electromechanical coupling coefficient, b is the magnetic conduction width of the yoke iron, δ1 is the wall thickness of the metal wire frame, ρ* is the resistivity, and W is the number of turns of the coil.

7. The design method of the moving coil geophone core according to claim 1, characterized in that, The inner magnetic circuit component is axially arranged inside the housing of the moving coil geophone core, and the axial ends of the inner magnetic circuit component are clamped with the two ends of the housing of the moving coil geophone core.

8. The design method of the moving coil geophone core according to claim 1, characterized in that, The main magnetic circuit adjusts the main magnetic field strength through the magnetic field generated by the bipolar opposite-top combined magnet and the corresponding magnetic conduction width.

9. The design method of the moving coil geophone core according to claim 1, characterized in that, The auxiliary magnetic circuit adjusts the turbine damping factor by setting an eddy current ring with adjustable magnetic conduction width.

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