CN205562824U - A Low Distortion Omnidirectional Geophone - Google Patents

Abstract

The utility model relates to a low distortion omnidirectional geophone, which comprises a shell, an upper top cover, a lower top cover, an inertial body system and a magnetic system; the inertial body system comprises an upper coil, a lower coil and a weight adjusting coil; the magnetic system comprises a magnet, an upper pole shoe, a lower pole shoe and a compensation ring. The end face of the upper pole shoe, which is far away from the magnet, is recorded as an end face A, the end face of the lower pole shoe, which is far away from the magnet, is recorded as an end face B, the end face of the upper coil, which is far away from the magnet, is recorded as an end face C, the end face of the lower coil, which is far away from the magnet, is recorded as an end face D, and the end faces C and D are located. The geophone is scaled up or down to a distance H between end faces A and B_ABNormalized to H_ABWhen the diameter is 25.4mm, the distance between the end face C and the end face A and the distance between the end face D and the end face B satisfy 0.6mm ≤ S_CA＝S_DBLess than or equal to 3 mm. The utility model discloses a injecing the distance of coil terminal surface to pole shoe terminal surface, making the wave detector distortion degree obtain very big improvement, it is minimum to the influence of sensitivity simultaneously.

Description

A Low Distortion Omnidirectional Geophone

technical field

The utility model relates to a geophone, in particular to an internal magnetic induction omnidirectional geophone used for complex ground conditions (such as underground, ocean, etc., which are difficult to be buried correctly), seismic survey and engineering survey.

Background technique

With the extension of geophysical exploration to the deep sea, deep strata and complex terrain, in order to solve the problem of embedding and complex coupling, omnidirectional geophones with various specifications and types have appeared in the industry. But the ensuing problem is that the existing omnidirectional geophones cannot provide higher exploration resolution, and the original promising omnidirectional technology has been greatly restricted in application: the existing technology cannot A breakthrough has been made in the distortion of the geophone, and its harmonic distortion is in the range of ≤0.6% to 0.9% (17.8mm/s excitation), which makes it impossible to achieve high-precision exploration (generally speaking, the lower the distortion of the geophone, the better The higher the resolution, the more beneficial it is to distinguish the weak high-frequency signals submerged in the low-frequency strong noise, that is to say, it has a larger dynamic range); on the other hand, there is a wider market demand for high-resolution exploration, According to the development trend of technology and equipment in the same industry at home and abroad, as well as the urgent requirements of ocean exploration, the demand for low-distortion omnidirectional geophones is immeasurable.

Due to the inherent characteristics of the elastic material and natural phenomena such as the mass of the inertial body being subject to the gravitational force of the earth, the inertial body carried by the elastic material is relative to the magnetic center of the magnetic system within the omnidirectional angle range, except for the defined symmetrical displacement working angle (such as the horizontal position ) except for asymmetric displacement work. This natural phenomenon is prone to increase such as asymmetric tolerance of frequency and sensitivity index and harmonic distortion (harmonic distortion is a kind of nonlinear distortion characterized by an input frequency that produces harmonics).

Generally speaking, when the natural frequency exceeds 18Hz, the geophone can obtain satisfactory data in the omnidirectional angle acquisition and detection source signal; when the natural frequency is lower than 18Hz, the natural frequency for the geophone to work in the omnidirectional angle is Between 10Hz and 18Hz, but as the natural frequency decreases, the frequency tolerance, sensitivity tolerance, harmonic distortion and other indicators of the omnidirectional angle will increase significantly. In the past few decades, people have mainly studied omnidirectional geophones with a natural frequency of 13 Hz to 15 Hz, but no matter how large the natural frequency is, the goal pursued is to keep the natural frequency as small as possible and the index tolerance as possible Narrow, harmonic distortion as low as possible.

Fig. 1 is a structural schematic diagram of an omnidirectional geophone in the prior art, which is divided into three parts: a structure, a magnetic circuit and an electric circuit. The breakdown is as follows:

1. Structure:

(1) Components: ① A magnetic system. From bottom to top in the axial direction, the lower end of the magnet 115 is embedded in the cap of the lower pole shoe 123 ; the upper end of the magnet 115 is embedded in the cap of the upper pole shoe 113 ; ② An inertial body system. From bottom to top in the axial direction, the lower coil 117 is wound on the lower coil frame 118; A lower spring piece 121 and a lower snap ring 124 are embedded at the lower end; an upper spring sheet 110 and an upper snap ring 102 are embedded at the upper end of the upper wire frame 111 .

(2) Composition and principle: The magnetic system is placed in the inertial body system, and the lower top cover 119 and the upper top cover 101 (the lower top cover 119 and the upper top cover 101 are pushed into the blinds of the lower pole piece 123 and the upper pole piece 113 respectively). In the hole) and the shell 125 form a geophone. The inertial body system in the geophone is carried by the upper spring piece 110 and the lower spring piece 121 on the inertial body, and moves up and down relative to the magnetic system to receive vibration signals.

2. Magnetic circuit: (1) Composition: The magnetic circuit is composed of the magnetic system and the casing 125 , and the annular air gap magnetic field formed between the magnetic system and the casing 125 .

(2) Principle: The upper coil 112 and the lower coil 117 of the forward and reverse winding on the inertial body are carried together by the upper spring piece 110 and the lower spring piece 121, and move up and down in the annular air gap magnetic field relative to the magnetic system. The vibration signal cuts the lines of magnetic force, and induces electrical signals with sensitivity and distortion as scalar indicators, which are output by the circuit of the geophone.

3. Circuit: the terminal 104 and the terminal 105 are two electrodes for the electrical signal output of the geophone respectively. The circuit circuit of the electrical signal is: the terminal 104 is soldered to the upper inner contact reed 103; the upper inner contact reed 103 contacts the upper pole piece 113, the magnet 115, the lower pole piece 123, and the lower spring piece 121 in sequence; The lower spring piece 121 is soldered to the lower outlet end of the lower coil 117; the upper outlet end of the lower coil 117 is insulated and communicated with the lower outlet end of the upper coil 112 through the surface of the weight adjustment coil 116; the upper outlet end of the upper coil 112 is soldered to the upper spring piece 110 The upper spring piece 110 is insulated and isolated from the upper pole piece 113 through the insulating piece 108, and is in contact with the upper outer contact reed 107; the upper outer contact reed 107 is soldered to the terminal 105.

Combining the composition and principle of the above-mentioned omnidirectional geophones, it is currently believed that there are two main reasons for harmonic distortion: one is the harmonic distortion produced by elastic materials, which is called elastic distortion; the other is the harmonic distortion produced by magnetic materials. Harmonic distortion is called magnetic field distortion.

1. For elastic distortion:

It is well recognized that the reeds of the geophones are the cause of the elastic distortion, so several different geophone reed structures have been developed in an attempt to reduce the generation of extra harmonics, including in US Patent Nos. US5555222 and US4623991 Public reed. Although it is somewhat effective in reducing harmonic distortion, the newly developed reed cannot completely solve the problem, and the residual distortion has a significant impact on the resolution of the input signal. As for the omnidirectional seismometer whose natural frequency is 10Hz-18Hz, due to the asymmetry caused by the influence of the earth's gravitational force, further research remains to be done.

Second, for the magnetic field distortion:

Magnetic field distortion is caused by the inability to ensure that the coil of the geophone and the magnetic field cut the magnetic force line perpendicularly or are in a uniform parallel magnetic field within the omnidirectional working angle.

In order to obtain effective output with high sensitivity, almost all designs are based on the principle of magnetic center symmetry to maximize the ratio of the length of the coil to the length of the pole piece (where the length of the pole piece is from the end in contact with the magnet to the opposite side of the pole piece) The length of that end), but the consequence of this is that the harmonic distortion is very large. Fig. 1 is a structural schematic diagram of an omnidirectional geophone in the prior art. The length of the coil is obviously greater than the length of the pole piece. The real distortion radar images of the omnidirectional geophone with this structure are shown in Fig. 2A and Fig. 2B, and the harmonic distortion is very large (harmonic distortion ≤0.8%, 17.8mm/s excitation).

US Patent No. 5,469,408 (ZL95195123.8) uses a design in which the length of the coil is less than the length of the pole piece. However, this technology does not take into account the influence of the asymmetry of the coil relative to the magnetic center on the harmonic distortion of the geophone with a natural frequency of 10 Hz to 18 Hz in an omnidirectional working environment, but only for the geophone in the vertical or horizontal When working at a fixed angle, the relative displacement of the coil is symmetrical to the magnetic center, and the relative displacement of the coil is small (peak-peak displacement ≤ 2mm), so as to maximize the use of the uniform magnetic field and reduce the distortion. The patent provides the harmonic distortion diagram when the geophone provided by it is in the best position, and the typical value of the harmonic distortion is 0.02%. Inspired by this technology, people try to continuously increase the relative displacement of the coil relative to the magnetic center in order to reduce the harmonic distortion of the omnidirectional geophone, but the effect is not ideal, and it has not been possible to find the harmonic distortion The significantly reduced critical point cannot meet the requirements of omnidirectional geophones for harmonic distortion.

Utility model content

In order to solve the problem of high harmonic distortion of omnidirectional geophones in the above background, the utility model provides a low-distortion omnidirectional geophone.

The design idea of the utility model is that when the geophone works at any angle, the relative displacement of the coil is symmetrical to the magnetic center, and the utilization of the uniform magnetic field has a larger redundant design, which can reduce the sensitivity of the geophone to almost no A significant reduction in harmonic distortion is obtained without the influence of the harmonics.

The technical scheme of the utility model is:

A low-distortion omnidirectional geophone, comprising a casing, an upper top cover, a lower top cover, an inertial body system, and a magnetic system; the inertial body system includes an upper coil, a lower coil, and a weighting coil; the magnetic system includes a magnet , upper pole shoe, lower pole shoe, and compensation ring; the end face of the upper pole shoe far away from the magnet is marked as end face A, the end face of the lower pole shoe far away from the magnet is marked as end face B; the end face of the upper coil far away from the magnet is marked as end face C, and the end face of the lower The end face of the coil away from the magnet is marked as end face D; its special feature is that: the end face C and the end face D are located between the end face A and the end face B; the geophone is scaled up or down, so that the end face A and the end face B When the distance H _AB is standardized as H _AB =25.4mm, the distance between end surface C and end surface A, and the distance between end surface D and end surface B satisfy 0.6mm≤S _CA =S _DB ≤3mm.

The effect is best when the above S _CA =S _DB =1.1 mm, and the harmonic distortion is minimized.

The above-mentioned geophone is suitable for an omnidirectional working environment with a natural frequency of 10 Hz to 18 Hz.

The above-mentioned geophones have the best detection effect in an omnidirectional working environment with a natural frequency of 13 Hz to 15 Hz.

The beneficial effects of the utility model are:

1. The utility model takes into account that the asymmetry of the coil relative to the magnetic center affects the harmonic distortion in the omnidirectional working environment of the geophone, especially in the low frequency (natural frequency 10Hz-18Hz) omnidirectional working environment. Influenced by determining that the distance between the end face of the coil and the end face of the corresponding pole piece is greater than 0.6mm, the degree of distortion is greatly improved with a very small loss of sensitivity.

2. When S _CA ＝S _DB ＝0.6mm, the harmonic distortion decreases sharply to ≤0.5% (17.8mm/s excitation); when S _CA ＝S _DB ＝1.1mm, the harmonic distortion further decreases to ≤0.3% (17.8mm/s excitation).

3. The geophone of the utility model is suitable for an omnidirectional working environment with a natural frequency of 10 Hz to 18 Hz, and the detection effect is the best in an omnidirectional working environment with a natural frequency of 13 Hz to 15 Hz.

Description of drawings

Fig. 1 is the structural representation of the omnidirectional geophone of prior art; Label among the figure: top cover on 101, snap ring on 102, inner contact reed on 103, terminal post 104,105, 106 circuit boards, outer on 107 Contact reed, 108 insulating sheet, 109 upper sealing ring, 110 upper spring leaf, 111 upper wire rack, 112 upper coil; 113 upper pole shoe, 115 magnet, 116 weight adjustment coil, 117 lower coil, 118 lower wire rack, 119 lower Top cover, 120 lower sealing rings, 121 lower spring sheets, 122 lower contact pieces, 123 lower pole shoes, 124 lower snap rings, 125 outer shells;

Fig. 2A is the distorted radar map (5.08mm/s excitation) of existing omnidirectional geophone;

Fig. 2B is the distorted radar map (17.8mm/s excitation) of existing omnidirectional geophone;

Fig. 3 is the structural representation of the omnidirectional geophone of the present utility model; Label among the figure: 301 upper top cover, 302 upper snap rings, 303 upper inner contact reeds, 304,305 terminal posts, 306 circuit boards, 307 upper outer Contact reed, 308 spring washer, 309 insulation sheet, 310 upper spring sheet, 311 upper sealing ring; 312 upper wire frame, 313 upper coil; 314 upper pole shoe, 315 compensation ring, 316 magnet, 317 weight adjustment coil, 318 lower Coil, 319 lower pole shoe, 320 lower wire frame, 321 lower top cover, 322 lower sealing ring, 323 lower spring leaf, 324 lower contact piece, 325 lower snap ring, 326 shell;

Fig. 4A is the distortion radar map of the present invention (S _CA =S _DB =0.6mm, 5.08mm/s excitation);

Fig. 4B is the distortion radar map of the present invention (S _CA =S _DB =0.6mm, 17.8mm/s excitation);

Fig. 4C is a distortion radar map of the present invention (S _CA =S _DB =1.1mm, 5.08mm/s excitation);

Fig. 4D is a distortion radar map of the present invention (S _CA =S _DB =1.1mm, 17.8mm/s excitation).

detailed description

Below in conjunction with accompanying drawing and specific embodiment, the utility model is further elaborated.

The utility model provides a low-distortion omnidirectional geophone, which includes an upper wire frame 312, an upper coil 313, a lower wire frame 320, a lower coil 318, a weight adjustment coil 317, a magnet 316, an insulating sheet 309, an upper pole shoe 314, Lower pole shoe 319, upper spring piece 310, lower spring piece 323, upper snap ring 302, lower snap ring 325, upper top cover 301, lower top cover 321, shell 326, spring washer 308, terminal post 304, terminal post 305 , upper inner contact reed 303, upper outer contact reed 307;

The two terminal posts 304 and 305 are respectively 2 electrodes of the electric signal output of the omnidirectional geophone; the circuit loop of the electric signal is that the terminal post 304 is soldered to the upper inner contact reed 303; the upper inner contact reed 303 is connected to the upper pole Boot 314, magnet 316, lower pole shoe 319, and lower spring sheet 323 are contacted successively in sequence; lower spring sheet 323 is soldered to the lower outlet end of lower coil 318; 313 is connected to the lower outlet terminal; the upper outlet terminal of the upper coil 313 is soldered to the upper spring piece 310; the upper spring piece 310 is insulated and isolated from the upper pole piece 314 through the insulating piece 309, and is in contact with the upper outer contact reed 307; the upper outer contact The reed 307 is soldered to the terminal 305 .

The magnetic system of the present utility model: the magnet 316 is covered with a compensating ring 315, the lower end of the magnet 316 is embedded in the cap of the lower pole shoe 319, the upper end of the magnet 316 is embedded in the cap of the upper pole shoe 314; an insulating sheet 309 is placed on the upper surface of the upper pole shoe 314 ;

The inertia body system of the present utility model: from bottom to top in the axial direction, the lower end of the lower wire frame 320 is embedded with a lower spring piece 323 and a lower snap ring 325; the lower wire frame 320 is wound with a lower coil 318; A weight adjustment coil 317 is wound around the bonded middle part; an upper coil 313 is wound around the upper wire frame 312; an upper spring piece 310 and an upper snap ring 302 are embedded in the upper end of the upper wire frame 312;

The magnetic system is placed in the inertial body system, and consists of a lower top cover 321, an upper top cover 301 (the lower top cover 321 and the upper top cover 301 are pushed into the blind holes of the lower pole piece 319 and the upper pole piece 314 respectively) and a casing 326 Omnidirectional geophones.

The working process of the utility model is: the inertial body system in the omnidirectional geophone is carried by the upper spring piece 310 and the lower spring piece 323 on the inertial body together, relatively moves up and down relative to the magnetic system, and receives the vibration signal; On the body, the upper coil 313 and the lower coil 318, which are wound forward and backward, are carried together by the upper spring piece 310 and the lower spring piece 323. Relative to the magnetic system, they move up and down in the annular air gap magnetic field, receive vibration signals, and cut the magnetic field lines. The electrical signal with sensitivity and distortion as scalar indicators is induced, and is output by the circuit of the omnidirectional geophone.

In order to reduce the harmonic distortion of the omnidirectional geophone as much as possible under the premise of ensuring the sensitivity of the omnidirectional geophone, as shown in Figure 3, the distance between the upper end face (end face C) of the upper coil 313 and the upper pole The distance between the upper end surface (end surface A) of the shoe 314, the distance between the lower end surface (end surface D) of the lower coil 318 and the lower end surface (end surface B) of the lower pole shoe 319 are defined as follows:

Firstly, the geophone is scaled up or down so that the distance H _AB between the end face A and the end face B is standardized as H _AB = 25.4mm, then the distance between the end face C and the end face A, the distance between the end face D and the end face B The distance between them satisfies 0.6mm≤S _CA =S _DB ≤3mm, and the end face C and end face D are located between end face A and end face B (that is, the length of the upper coil is less than the length of the upper pole piece, and the length of the lower coil is less than the length of the lower pole piece length).

1. When S _CA =S _DB =0.6mm, the harmonic distortion of the utility model can be reduced to:

(1) Harmonic distortion ≤ 0.2% (5.08mm/s excitation), the corresponding distortion curve is shown in Figure 4A, 90° and 270° in the figure are the horizontal positions of the core;

(2) Harmonic distortion ≤ 0.45% (17.8mm/s excitation), the corresponding distortion curve is shown in Figure 4B, 90° and 270° in the figure are the horizontal positions of the core.

2. When S _CA =S _DB =1.1, the harmonic distortion of the present invention can be reduced to:

(1) Harmonic distortion ≤ 0.1% (5.08mm/s excitation), the corresponding distortion curve is shown in Figure 4C, 90° and 270° in the figure are the horizontal positions of the core;

(2) Harmonic distortion ≤ 0.2% (17.8mm/s excitation), the corresponding distortion curve is shown in Figure 4D, 90° and 270° in the figure are the horizontal positions of the core.

3. When S _CA =S _DB increases gradually in the interval [1,3], the harmonic distortion of the utility model does not change substantially, and the distortion curve is the same as the distortion curve of S _CA =S _DB =1.1mm, At the same time, the sensitivity loss of the utility model is extremely small; however, when S _CA =S _DB > 3mm, the sensitivity of the utility model decreases, which cannot meet the exploration requirements, and the distortion degree is meaningless at this time.

And the harmonic distortion of the omnidirectional geophone of prior art is:

(1) Harmonic distortion ≤ 0.25% (5.08mm/s excitation), the corresponding distortion curve is shown in Figure 2A, 90° and 270° in the figure are the horizontal positions of the core;

(2) Harmonic distortion ≤ 0.8% (17.8mm/s excitation), the corresponding distortion curve is shown in Figure 2B, 90° and 270° in the figure are the horizontal positions of the core.

Note: The above distortion curves are generated from the data obtained from the distortion detection of omnidirectional geophones according to GB/T24260-2009.

Claims (4)

1. A low-distortion omnidirectional geophone, comprising a shell, an upper top cover, a lower top cover, an inertial body system, and a magnetic system; the inertial body system includes an upper coil, a lower coil, and a weight adjustment coil; the magnetic system Including magnet, upper pole shoe, lower pole shoe, and compensation ring; the end face of the upper pole shoe far away from the magnet is marked as end face A, the end face of the lower pole shoe far away from the magnet is marked as end face B; the end face of the upper coil far away from the magnet is marked as end face C , the end face of the lower coil away from the magnet is marked as end face D; it is characterized in that: The end face C and the end face D are located between the end face A and the end face B; When the geophone is scaled up or down so that the distance H _AB between the end face A and the end face B is standardized as H _AB =25.4mm, the distance between the end face C and the end face A, the distance between the end face D and the end face B The distance between them satisfies 0.6mm≤S _CA =S _DB ≤3mm. 2. A low-distortion omnidirectional geophone according to claim 1, characterized in that: said S _CA =S _DB =1.1 mm. 3. The low-distortion omnidirectional geophone according to claim 2, characterized in that: the natural frequency of the omnidirectional geophone is 10 Hz-18 Hz. 4. A low-distortion omnidirectional geophone according to claim 3, characterized in that: the natural frequency of the omnidirectional geophone is 13Hz-15Hz.