CN1277363A - Geophone with radial magnetic path structure - Google Patents

Abstract

The geophone consists of casing, upper and lower cover, magnetically separately support rings, lining, radial permanent magnet, iron core, regulating core, inertia body, leaf spring, etc. A strong homogeneous magnetic field is formed between the radial permanent magnet and the iron core to raise the sensitivity of the geophone and reduce harmonic distortion; the regulating core in magnetic loop ensures the performance uniformity of geophones, and the excellent magnetic closure ensures its electromagnetic interference resistance. The geophone is used mainly in high-resolution exploration and three dimensional seismic exploration and may be used also in the detection of other vibration signal.

Description

A kind of seismoreceiver of radial magnetic structure

The invention belongs to earthquake detector arrangement class fields of measurement, specifically is exactly a kind of seismoreceiver that comprises speed and acceleration (eddy current) type, can be used for geologic prospecting, seismic surveying and engineering survey.

Seismoreceiver is that a kind of being used for converts seismic energy and the corresponding voltage sensor of seimic wave velocity to.The most general existing seismoreceiver is exactly a kind of speed-type geophone, it is according to Faraday's electromagnetic induction law, if every MLT mean length of turn is L, the number of turn is that the coil of N is done cutting magnetic line movement with relative velocity ν in magnetic field B, will induce induction electromotive force e at the coil two ends so, e is numerically equal to the product of NBL ν, and wherein B is the magnetic induction density in magnetic field.When the coil perpendicular cuts magnetic line of force, magnitude of voltage (induction electromotive force value) is proportional to because of the relative velocity ν of the caused coil of seismic energy for permanent magnet.Can suppose that magnetic flux density B is essentially a constant, can design the voltage signal that a circuit comes the monitor earthquake wave detector to be produced, this signal is in order to information such as construction locations under the face of land of prediction reflection seismic energy.

The structure of the most frequently used speed-type geophone is with reference to Fig. 1, comprise up and down two pole shoe (yokes) 7 and permanent magnet 6 at an interior cover magnet assembly, be installed within columniform shell 3 and the coil former 5, and between magnet assembly and shell 3, set up a magnetic field in the air gap 8.Have the toroid winding frame 5 that is around in coil 4 on it and be suspended on annular space between magnet assembly 6,7 and the shell 3 by spring leaf 2.When seismic event makes shell 3 motions, coil just moves in magnetic field, hysteresis when beginning, coil is arranged, being loaded on spring leaf below the top cover 1 subsequently drives and moves reciprocatingly by its original position, cutting magnetic line also produces induced voltage signal at the coil two ends, this voltage signal is proportional to coil movement speed, therefore abbreviates speed-type geophone as.

The said structure seismoreceiver, if want to improve geophone sensitivity, effective turn with regard to magnetic induction density and coil in the needs increase air gap, but because pole shoe is two blocks of permeability magnetic materials, be positioned at the permanent magnet two ends, and be processed to definite shape, to control DISTRIBUTION OF MAGNETIC FIELD in the adjacent air gap, thereby be subjected to the restriction of certain size, so the magnetic induction density that produces with deficiency so that geophone sensitivity be greatly improved, equally, the coil effective turn also is subjected to size restrictions, and therefore wanting to improve sensitivity will be subjected to certain limitation.

Because the spring leaf of seismoreceiver is the main cause that produces the harmonic distortion of wave detector output signal, therefore has the people to develop multiple difform chip architecture of the spring, attempts to reduce the generation of extra harmonic wave.Though in some achievement aspect the minimizing harmonic wave, the spring leaf of being developed design can not be dealt with problems fully, and residual distortion still has a significant effect to input signal resolution with the method.Because harmonic distortion is a kind of nonlinear distortion that can produce the harmonic content feature with an incoming frequency.This influence is more obvious than performance in the two-dimension earthquake data in 3D seismic data.It is found that simultaneously coil in non-uniform magnetic-field, move also can be significantly non-linear influential to the seismoreceiver loop, thereby also have influence on harmonic distortion.

Existing speed-type geophone is because the defective in the magnetic structure design exists the relatively poor shortcoming of magnetic closure, thereby makes in the wave detector output signal anti-electromagnetic interference capability relatively poor.

The a plurality of wave detector series and parallels of most employings are used in combination in the actual use of seismoreceiver.Because the consistency problem of geophone property often makes the earthquake information data can not correctly obtain reflection.Thereby just need a plurality of wave detectors that less deviation is in use arranged each other, keep the performance unanimity as far as possible.Original velocity profile detector structure is to be difficult to realize this requirement.

Defectives such as therefore, existing seismoreceiver all exists sensitivity low, and harmonic distortion is big, and the little and string of anti-electromagnetic interference capability also, consistency of performance was relatively poor when connection used can not satisfy the high-acruracy survey needs.

Purpose of the present invention just is to provide a kind of high sensitivity that has, less distortion, and strong anti-electromagnetic interference capability, the output performance consistance is the seismoreceiver of radial magnetic structure preferably.

The present invention realizes as follows.

With a cover magnet assembly, comprise shell, up and down top cover, constitute an annulus gap magnetic field every magnetic supporting ring, annular permanent magnet, magnetic core (iron core) up and down.The coasting body that comprises coil, coil former, spring leaf with a cover between permanent magnet and magnetic core in the annulus gap magnetic field motion produce induced voltage.With this voltage signal output, just can realize having the seismoreceiver of radial magnetic structure with a cover output unit.

The present invention has following advantage.

Because the radial permanent magnet that adopts is one and has coercive force greater than 320 kilo-ampere/rice, remanent magnetism is greater than the annular permanent magnet of 0.6 tesla, therefore the annulus gap space between radial permanent magnet and magnetic core can form strong and wide effective uniform magnetic field, thereby makes coil can produce high-resolution linear output signal when motion.Relatively with the seismoreceiver of pre-structure, it is a kind of brand-new magnetic structure, can significantly improve the sensitivity of wave detector and the harmonic distortion in the reduction wave detector output signal.Utilize the magnetic sealing characteristics of this magnetic structure, can reduce the electromagnetic interference (EMI) of outer signals, can strengthen the electromagnetic screen ability of wave detector own, reduce the electromagnetic interference signal in the output signal wave detector.If adopt an adjusting fuse that is threaded structure at magnetic core and following top cap central bore, the magnetic flux cross section that just can change magnetic core by change adjusting fuse size is long-pending, regulates its output performance thereby reach, and makes wave detector property retention unanimity in actual use.If control coil axial length and permanent magnet axial length ratio are between 0.5 to 1.5, then the magnetic field that is provided can be wideer more even, and harmonic distortion will be littler.

Description of drawings.

Fig. 1 is the structural representation of the most frequently used speed-type geophone.

Fig. 2 is a kind of speed-type geophone structural representation of radial magnetic structure.

Below in conjunction with accompanying drawing in detail embodiments of the invention are described in detail.

Speed-type geophone structure with reference to a kind of radial magnetic structure of Fig. 2 comprises a cover magnet assembly, a cover coasting body assembly and a cover signal output apparatus.

One cover magnet assembly comprises every magnetic supporting ring 6 with down every magnetic supporting ring 13, by permanent magnet 9, and lining 10, air gap 7, magnetic core 15 is regulated fuse 16, loam cake 2, lower cover 17, shell 8 is formed a magnetic loop.In the annular space of air gap 7 between magnetic core 15 and permanent magnet 9, in air gap 7, form the magnetic field that can supply coil 11 to do cutting magnetic line movement.

One cover coasting body structure, comprise a coil former 12, be wound with coil 11 above, coil former 12 is positioned at the annular space between permanent magnet 9 linings 10 and the magnetic core (iron core) 15, and be suspended in the annular space by upper spring sheet 3 and lower spring sheet 14, in the air gap 7 magnetic field that magnetic circuit forms, so that coil 11 is moved in annulus gap 7 with respect to shell 8.When coil former 12 was static, coil 11 was positioned at the annular space center.Seismic energy impels coil 11 that motion with respect to permanent magnet 9 and magnetic core 15 takes place in air gap 7, thereby produces a voltage signal, and this voltage signal is proportional to the relative velocity of 11 pairs of permanent magnets 9 of coil.

One cover signal output apparatus, comprise connection terminal 5 and button silk 4, register pin 1 is arranged on the loam cake 2, rotate freely in order to limiting coil frame 12, prevent that excessive rotation from twisting off button silk 4, to guarantee that voltage signal output has good being electrically connected, register pin allows coil former to move reciprocatingly by the original position, but produces measurement voltage signal with cutting magnetic line and at coil 11 output terminals.

Last magnetism-isolating loop 6 and following magnetism-isolating loop 13 use non-magnet material or pyromagnetic compensator alloy material, its effect one is to stop magnetic circuit to form magnet short-cut path, the 2nd, be used for fixing permanent magnet 9, three, the performance of permanent magnet 9 is carried out temperature compensation, generally can select to have the alloy material of pyromagnetic compensation performance.

Permanent magnet 9 adopts a kind of rareearth magnetic material with enough high-coercive forces and remanent magnetism, and it provides sufficiently high magnetic induction density can for air gap 7, so that coil can produce the output response.Adopt any high energy product material all can produce a uniform magnetic field that can allow seismoreceiver work.Its effect of rare-earth permanent magnet used in the present invention is very good.For example, use the rare-earth Nd-Fe-B material, the easy oxidation of neodymium iron boron magnetic body and quite crisp is so should plate one deck zinc or nickel to permanent magnet surfaces before putting into wave detector.To prevent that permanent magnet is oxidized in manufacturing and open-air use.

Radial permanent magnet 9 is toroidal magnets, can form a whole radial toroidal magnet by 2 to 16 radial annular permanent magnets, also can form a whole radial toroidal magnet by 2 to 36 tile-shaped magnets.The permanent magnet 9 that uses radial toroidal magnet to form can not use lining 10, to reduce wave detector overall volume and the further magnetic induction density that improves in the air gap 7.The radial permanent magnet that adopts above-mentioned technology to make has strong and wide effective uniform magnetic field of formation in annulus gap 7.

Magnetic core 15, loam cake 2, lower cover 17 and shell 8 are made by permeability magnetic material, locate upper spring sheet 3 and lower spring sheet 14 with loam cake 2 lower covers 17 and magnetic core 15, make spring leaf be enough to support coils frame 12 and around thereon coil 11.One hole is arranged in the middle of magnetic core 15, in the middle of lower cover 17 threaded hole is arranged, magnetic core 15 and lower cover 17 also can be all solid construction.

Regulate fuse 16 and made by permeability magnetic material, one of its shape is a right cylinder, and the other end is threaded structure, and coaxial with magnetic core 15 and lower cover 17.Regulating fuse is fixed on the lower cover 17, the magnetic flux cross section that can change magnetic core by the adjusting fuse 16 in the change magnetic loop is long-pending, thereby regulate the magnetic induction density in the air gap 7, reach and regulate its output performance, satisfy seismoreceiver and use the requirement of consistency of performance each other.

Upper spring sheet 3 and lower spring sheet 14 are to make the spider shape by thin material, and this material is the resilient material of non-magnetic conduction, have ring and an outer shroud in one, connect this two ring with quite thin arc elastic arm.

Although provided by the present invention is a kind of seismoreceiver of flexible coupling, coil former is subjected to certain constraint with respect to rotating freely of magnetic core, but radial magnetic structure also can be used for rotary-type seismoreceiver, coil former in its structure can rotate freely with respect to magnetic core, just can realize as long as change its electric connecting mode.

Claims (6)

1, a kind of seismoreceiver of radial magnetic structure is by constituting a radial magnetic loop every magnetic supporting ring, radial permanent magnet, air gap, magnetic core, loam cake, lower cover and shell.Constitute a cover coasting body by coil former, coil, spring leaf.Constitute a cover signal output apparatus by connection terminal, button silk and register pin, it is characterized in that:

Annular space between permanent magnet and magnetic core forms an air-gap field by force and uniformly, radial permanent magnet is an annular solid made from rare earth material, magnetic core, and loam cake, lower cover, shell are made by permeability magnetic material, magnetic core and lower cover are all solid construction, adopt non-magnet material every the magnetic supporting ring.

2,, it is characterized in that radial permanent magnet makes with the rare-earth Nd-Fe-B material, by 2 to 16 radial permanent magnets of the radial magnet combination of annular annular in aggregates by the seismoreceiver of claim 1.

3, by the seismoreceiver of claim 1, it is characterized in that radial permanent magnet by the synthetic integral ring-shaped radial permanent magnet of 2 to 36 pieces watts shape set of permanent magnets, has a lining in the integral ring-shaped radial permanent magnet of combination, lining is made by permeability magnetic material.

4, by the seismoreceiver of claim 1, it is characterized in that every the magnetic supporting ring it being to make by alloy material with pyromagnetic temperature compensation function.

5, press the seismoreceiver of claim 1, it is characterized in that magnetic core has a center pit, under be stamped a threaded hole, have one to regulate fuse in core center hole and the lower cover threaded hole, regulate fuse and made by permeability magnetic material, regulating one in fuse is right cylinder, and the other end is threaded structure, be fixed on down and cover, coaxial with magnetic core and lower cover.

6, by the seismoreceiver of claim 1, the axial length that it is characterized in that coil is 0.5 with the ratio of the axial length of radial magnet at least, is 1.5 at the most.