Damping-adjustable clinometer

Abstract

The utility model belongs to the technical field of precision measuring devices, and particularly relates to a damping-adjustable clinometer. The device comprises a swing type inclination unit and a damping excitation unit, the swing type inclined unit comprises a vertical swing structure and fixed polar plates respectively arranged on two sides of the vertical swing structure, and the vertical swing structure and the two fixed polar plates form a differential variable-spacing capacitance detection structure; the damping excitation unit comprises an electrified coil arranged below or on the side of the vertical pendulum structure, and the electrified coil is made of a superconducting material; the vertical pendulum structure is made of a conductive diamagnetic material, and the electrified coil and the vertical pendulum structure jointly form a damping unit. The device adopts non-contact eddy current damping, does not need a liquid or complex feedback system, has the advantages of simple structure, good low-temperature stability, wide damping adjustable range and the like, and is suitable for real-time dip angle monitoring of the probe in the superconducting gravimeter.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of precision measuring device, concretely relates to a damping adjustable tiltmeter. BACKGROUND

[0002] In the use process of the superconducting gravity meter, the sensitive axis direction of the probe needs to strictly coincide with the plumb line to accurately measure the change of the gravity value. However, in actual application, due to the inevitable errors in the installation process and the slow inclination change of the earth, the sensitive axis direction of the probe is prone to tilt, and therefore, we need to place a tiltmeter at the original position of the sensitive probe to detect the vertical change of the probe so as to perform feedback control and ensure that the sensitive axis direction strictly coincides with the plumb line.

[0003] The currently used ordinary pendulum tiltmeter only relies on film damping during work, has a long stabilization time, and seriously restricts the dynamic measurement of continuously changing inclination, and therefore, damping needs to be provided to the pendulum to quickly eliminate free swinging.

[0004] In the prior art, the tiltmeter usually adopts liquid damping (such as silicon oil) or active electromagnetic feedback. However, the liquid will undergo solidification phase change at low temperature, which will cause the damping characteristics to deteriorate sharply or even completely fail, and the liquid-solid interface is prone to produce micro-bubbles under the action of the temperature gradient, which will cause nonlinear fluctuation of the damping coefficient and seriously affect the measurement stability. The active control method of electromagnetic feedback needs to introduce a complex closed-loop control system, which will not only significantly increase the power consumption and volume of the instrument, but also cause feedback delay due to the noise interference of low-temperature electronic devices. Therefore, there is an urgent need for a tiltmeter suitable for low temperature, adjustable damping and simple structure. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a damping adjustable tiltmeter, which solves the problems of insufficient damping and long stabilization time in a low-temperature environment.

[0006] To achieve the above-mentioned purpose, the utility model provides a damping adjustable tiltmeter, which comprises a pendulum tilt unit and a damping excitation unit.

[0007] The damping excitation unit comprises an energized coil arranged below or beside the vertical pendulum structure, and the material of the energized coil is superconducting material; and the vertical pendulum structure adopts conductive diamagnetic material.

[0008] Further, the vertical pendulum structure comprises a reed and a pendulum bob suspended below the reed.

[0009] Further, the fixed pole plate is arranged on both sides of the pendulum bob.

[0010] Further, the material of the pendulum is oxygen-free copper, the material of the reed is beryllium copper alloy, and the material of the energized coil is niobium material.

[0011] Further, the reed is a single reed or a double reed, and the effective length is 20-25 mm and the thickness is 0.05-0.1 mm.

[0012] Further, the energized coil is arranged below the pendulum or arranged on the two fixed pole plates.

[0013] Further, the distance between the energized coil and the pendulum is greater than 0.5 mm.

[0014] Further, the energized coil is a square tubular coil, a square sheet coil, a circular tubular coil or a circular sheet coil.

[0015] Further, the energized coil is further connected with a current source, and the size of the current is adjusted by the current source.

[0016] Further, the inclinometer further comprises a frame base, the vertical pendulum structure is suspended on the top of the frame base, the fixed pole plate is fixed on the side wall of the frame base, and the energized coil is arranged on the bottom of the frame base or on the two fixed pole plates.

[0017] Overall, compared with the prior art, the above technical scheme of the present application mainly has the following technical advantages:

[0018] 1. The damping-adjustable inclinometer, the vertical pendulum structure is made of conductive anti-magnetic material, and the energized coil is arranged, the magnetic lines generated by the vertical pendulum structure when oscillating are used to form eddy current, the eddy current generates electromagnetic field opposite to the magnetic field direction of the energized coil, the two hinder each other, and the eddy current damping effect is generated.

[0019] 2. The superconducting energized coil and the oxygen-free copper pendulum are used to form a damping unit, the performance is stable in a 4.2K low-temperature environment, the damping characteristic failure problem caused by low-temperature solidification of the traditional liquid damping is avoided, and the long-term reliable operation of the inclinometer in the superconducting gravity meter is ensured.

[0020] 3、Damping ratio can be adjusted by various ways such as the shape of the energized coil, the number of turns, the size of the energizing current, the distance from the pendulum, the thickness of the pendulum, the base area, etc. The damping ratio control range can reach 0.001-0.9, which significantly improves the dynamic response performance of the inclinometer, can quickly reach a stable state, and meets the real-time requirements of high-precision inclination measurement.

[0021] 4、The pendulum and the energized coil are kept a certain gap, and run in a non-contact manner, avoiding the problem of increased mass load and stiffness commonly seen in most damping technologies, and without the need for complex active control circuit, improving the reliability and stability of the inclinometer in a low-temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The structure of the damping-adjustable inclinometer provided by the present application is shown in the figure.

[0023] Figure 2 The shape of the energized coil provided by the present application.

[0024] Figure 3 The output result of the inclinometer when it is tilted is provided by the present application.

[0025] Figure 4 The schematic diagram of the current injection mode of the energized coil provided by the present application.

[0026] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0027] 1-spring leaf; 2-pendulum; 3-fixed plate; 4-energized coil; 5-frame base. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear and understandable, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0029] As shown in Figure 1 A damping-adjustable inclinometer, comprising a pendulum tilt unit and a damping excitation unit. The pendulum tilt unit comprises a vertical pendulum structure composed of a spring leaf 1 and a pendulum 2, and a differential variable gap capacitance detection structure composed of the pendulum 2 and a fixed plate 3; the damping excitation unit is an energized coil 4 with adjustable current.

[0030] The spring leaf 1 can be a single spring leaf or a double spring leaf, with an effective length of 20-25mm and a thickness of 0.05-0.1mmFigure 1 The length direction of the pendulum 2 is the medium-high direction, and the thickness direction is the horizontal direction. The design can make the natural frequency of the pendulum 2 be 5-8 Hz, meet the low-frequency tilt measurement requirement, and the beryllium copper material has high elasticity and good low-temperature stability.

[0031] The pendulum 2 is made of high-conductivity diamagnetic material, preferably oxygen-free copper material. In a low-temperature environment, the electrical conductivity of oxygen-free copper can increase by 30-100 times, which can effectively increase the damping and improve the response speed of the tiltmeter measurement.

[0032] The pendulum 2 and the damping excitation unit have a certain gap. This damping scheme is easy to install and operates in a non-contact manner, so by adding it to the system, the mass load and stiffness increase commonly seen in most damping technologies can be avoided. At the same time, since the eddy current damping is used, there is no problem of solidification of traditional damping liquid at low temperature, and there is no need for complex active control circuit, which improves the reliability and stability of the tiltmeter in a low-temperature environment.

[0033] The pendulum 2 is connected to the DDS input signal, and forms a differential variable-gap capacitance detection structure with the fixed electrode plate 3, which can convert the tilt angle signal into a capacitance signal for output. When a tilt occurs, the pendulum 2 will produce displacement, which will cause the capacitance between the pendulum 2 and the fixed electrode plate 3 to change, and the two fixed electrode plates 3 output differential signals. The differential signals are transmitted to the capacitance displacement sensing circuit (normal temperature end) through the lead wire, and the signals are modulated and demodulated after output, and the tilt condition of the pendulum 2 can be obtained.

[0034] The energized coil 4 of the damping excitation unit is wound by a wire, which can be a square tubular coil, a square sheet coil, a circular tubular coil, or a circular sheet coil, as shown in Figure 2 The energized coil is made of niobium material, which can be placed individually under the pendulum 2 and placed on the frame base 5. This placement method can utilize the axial magnetic flux of the energized coil 4; or two energized coils 4 are placed on the sides of the pendulum 2 (which can be placed on the two fixed electrode plates 3). This placement method can utilize the radial magnetic flux of the energized coil 4, and the magnetic field directions of the opposite faces of the two energized coils 4 are opposite, which can further enhance the utilization rate of the magnetic induction intensity of the pendulum 2.

[0035] The energized coil 4 is also connected to a current source, as shown in Figure 4 The size of the current flowing through the current source can be adjusted, and the target current can be injected according to the damping requirement.

[0036] In the above scheme, when a tilt occurs, the reed 1 drives the pendulum 2 to oscillate freely with damping, but due to the low-temperature diaphragm damping ratio of only 10 -3The magnitude is large, and the stable time is long. After the energized coil 4 is placed, the magnetic flux passing through the conductor (the pendulum 2) will continuously change when the pendulum 2 vibrates and cuts the magnetic induction lines in the magnetic field. According to the Faraday's law of electromagnetic induction, the corresponding induced electromotive force will be generated in the conductor, forming an eddy current. The eddy current generates an electromagnetic field in the opposite direction of the magnetic field of the energized coil 4 itself, and the two hinder each other, generating an eddy current damping effect. Under the effect of the effect, the oscillation energy of the pendulum 2 is converted into thermal energy of the eddy current heating, and the oscillation speed gradually slows down until it stops, and then the rapid vibration damping is realized.

[0037] For example, the square tubular coil is placed at the bottom of the frame base 5. This placement utilizes the axial magnetic flux of the energized coil 4, and the axial magnetic flux density generated at the space P point can be expressed by the formula as follows:

[0038]

[0039] Wherein, μ0 is the magnetic permeability in vacuum, which is 4π×10 -7 H / m (Hen / m); N is the number of turns of the coil; I0 is the current passing through the coil; (x, y, z) is the coordinate of any point P in space; (x0, y0, z0) is the coordinate of a current element with a thickness of dz0 taken on the side surface of the coil; a, b, and h are the length, width, and total length of the square tubular coil in the z direction, respectively.

[0040] The damping force caused by the eddy current can be expressed by the formula as follows:

[0041]

[0042] Wherein, the induced current density σ is the electrical conductivity, v is the relative motion speed of the pendulum and the damping excitation unit, δ is the effective penetration depth of the magnetic field, and V is the volume of the conductor plate. The damping force is opposite to the direction of the speed. Under low-frequency vibration, the eddy current damping force is proportional to the first power of the speed, and the damping coefficient is a constant, which can be expressed by the formula as follows:

[0043]

[0044] S is the effective area through which the magnetic field passes.

[0045] Therefore, the size of the eddy current damping can be flexibly changed by changing the shape, number of turns, size of the energized coil 4, distance from the pendulum 2, thickness (penetration depth) of the pendulum 2, and bottom area, so as to realize the dynamic adjustment of the damping ratio at low temperature and meet the needs of different measurement scenes for damping.

[0046] In order to verify the damping effect of the energized coil 4, first test the damping effect without setting the damping excitation unit, specifically: the tiltmeter without setting the energized coil 4 is placed horizontally in the vacuum chamber (the probe is also in the vacuum chamber, at this time the tiltmeter and the probe are in the same environment, so the tilt angle is basically consistent, improving the detection accuracy), then put it into the dewar for low temperature environment test. The pendulum 2 is connected with the DDS input signal, and the two fixed pole plates 3 constitute a differential capacitive displacement detection unit. When the tilt occurs, the pendulum 2 will produce displacement, so as to cause the change of the capacitance between the pendulum 2 and the fixed pole plate 3. According to the corresponding relationship between the capacitance change and the tilt angle, the differential signal is output through the two fixed pole plates 3. The differential signal is transmitted to the capacitive displacement sensing circuit (normal temperature end) located above the dewar through the lead, and the signal is modulated and demodulated and then output. In the above scheme, when the tilt occurs, the reed 1 drives the pendulum 2 to do the damped free oscillation, but because the damping ratio of the pressure film at low temperature is only 10 -3 order of magnitude, the stable time is long, and it is not convenient for real-time detection.

[0047] Put the tiltmeter with the energized coil 4 assembled into the dewar for low temperature environment test. When oscillating, the pendulum 2 cuts the magnetic field lines generated by the energized coil 4, and the magnetic flux passing through the conductor will change continuously. According to Faraday's law of electromagnetic induction, a corresponding induced electromotive force will be generated in the conductor, forming an eddy current. The eddy current generates an electromagnetic field opposite to the magnetic field direction of the energized coil 4 itself, which hinders each other and produces eddy current damping effect. Under the effect of the effect, the oscillation energy of the pendulum 2 is converted into the heat energy of the eddy current heating, and the oscillation speed gradually slows down until it stops, realizing rapid damping.

[0048] The practical output result of the tiltmeter is as shown in the left graph of Figure 3 . Figure 3 The left graph in the middle is the damping ratio at normal temperature without placing the damping excitation unit, which is 0.001; after placing the damping excitation unit, the damping ratio at normal temperature can reach 0.031, and at low temperature it can be greater than 0.9, as shown in the right graph in the middle, which can be quickly stabilized. Figure 3 .

[0049] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A tiltmeter with adjustable damping, characterized in that, The tiltmeter comprises a pendulum tilt unit and a damping excitation unit; the pendulum tilt unit comprises a vertical pendulum structure and fixed pole plates (3) arranged on both sides of the vertical pendulum structure respectively, and the vertical pendulum structure and the two fixed pole plates (3) form a differential variable spacing capacitor detection structure; The damping excitation unit comprises a current coil (4) arranged below or beside the vertical pendulum structure, the material of the current coil (4) is superconducting material, and the vertical pendulum structure is made of conductive diamagnetic material.

2. The damped adjustable tiltmeter of claim 1, wherein, The vertical pendulum structure comprises a reed (1) and a pendulum bob (2) suspended below the reed (1).

3. The damped adjustable tiltmeter of claim 2, wherein, The fixed pole plates (3) are arranged on both sides of the pendulum bob (2).

4. The damped adjustable tiltmeter of claim 2, wherein, The material of the pendulum bob (2) is oxygen-free copper, the material of the reed (1) is beryllium copper alloy, and the material of the current coil (4) is niobium material.

5. The damped adjustable tiltmeter of claim 2, wherein, The reed (1) is a single reed or a double reed, the effective length is 20-25 mm, and the thickness is 0.05-0.1 mm.

6. The damped adjustable tiltmeter of claim 2, wherein, The current coil (4) is arranged below the pendulum bob (2) or two current coils (4) are arranged on the two fixed pole plates (3) respectively.

7. The damped adjustable tiltmeter of claim 6, wherein, The distance between the current coil (4) and the pendulum bob (2) is greater than 0.5 mm.

8. The damped adjustable tiltmeter of claim 1, wherein, The current coil (4) is a square tubular coil, a square sheet coil, a circular tubular coil or a circular sheet coil.

9. The damped adjustable tiltmeter of claim 1, wherein, The current coil (4) is further connected with a current source, and the size of the current is adjusted by the current source.

10. A damped adjustable tiltmeter according to any one of claims 1 to 9, wherein, The tiltmeter further comprises a frame base (5), the vertical pendulum structure is suspended on the top of the frame base (5), the fixed pole plates (3) are fixed on the side walls of the frame base (5), and the current coil (4) is placed on the bottom of the frame base (5) or on the two fixed pole plates (3).

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