CN103674005A - Magnetic shielding case of fiber-optic gyroscope - Google Patents

Abstract

The invention belongs to the optical fiber gyroscope technology, and relates to a reusable, easy-to-install and disassemble optical fiber gyroscope magnetic shielding cover. The optical fiber gyroscope magnetic shield includes an upper shield, a lower shield, a base, a skeleton, and an optical fiber ring. Wherein, the inner ring of the upper shielding case is located between the inner cylindrical surface of the frame and the side wall of the lower shielding case, and the optical fiber surrounds the outer circumference of the frame and is closed by the upper shielding case. The cover plate of the upper shield, the inner ring of the upper shield, the side wall of the lower shield, the bottom plate of the lower shield, the bottom plate of the upper shield, and the outer ring of the upper shield will form a closed magnetic circuit. The middle magnetically sensitive part is surrounded and perpendicular to the propagation direction of light, which realizes high-performance magnetic shielding, and also plays a role in protecting the optical fiber ring. In addition, the optical fiber gyroscope magnetic shielding cover of the present invention only uses fasteners to complete the assembly of various parts in the assembly process, and does not use glue or welding. The assembly and disassembly of the shielding cover are simple and easy.

Description

A fiber optic gyroscope magnetic shield

technical field

The invention belongs to the optical fiber gyroscope technology, and relates to a reusable, easy-to-install and disassemble optical fiber gyroscope magnetic shielding cover.

Background technique

Fiber optic gyroscope is a kind of optical gyroscope based on Sagnac effect, which generally includes fiber optic ring and its installation skeleton, light source, coupler, integrated optical modulator, detector, etc. The earth's magnetic field and the environmental magnetic field will have a great impact on the performance of fiber optic gyroscopes, especially high-precision gyroscopes, through the Faraday effect and the Cole effect.

As we all know, the magnetic field can cause a phase difference Δφ between the positive and negative beams of light in the fiber optic gyroscope through the Faraday effect,

where ζ ₀ is the Faraday rotation of the light, and its magnitude is the product of the magnetic field strength and the Wedel constant; R is the fiber radius; Δβ is the birefringence coefficient of the fiber; θ ₀ is the orientation angle of the magnetic field. Therefore, the magnetic field will produce an additional component in the output of the fiber optic gyro, which is independent of the gyro rotation speed. The test shows that when the magnetic shield is not installed, the output ω of the fiber optic gyroscope has a linear relationship with the magnetic induction intensity B:

ω＝K·B+B ₀

In the formula, ω is the output of the FOG, and B ₀ is the zero bias of the FOG. Especially for high-precision fiber optic gyroscopes, the error caused by the earth's magnetic field often exceeds the inherent zero bias of the gyroscope, so it is necessary to magnetically shield the sensitive parts of the gyroscope's magnetic field. For fiber optic gyroscopes, magnetic shielding is mainly aimed at DC or low-frequency magnetic fields. The magnetic shielding material provides a low reluctance channel in the magnetic field, guides the magnetic field lines through itself, and minimizes the magnetic field passing through sensitive parts. In fact, the upper and lower sets of magnetic shields made of high magnetic permeability materials are generally used to surround the sensitive part of the gyro optical path to the magnetic field, which can weaken the influence of the magnetic field.

The upper and lower magnetic shields are generally fixed by bonding or welding, which makes it difficult to disassemble during debugging and maintenance. The material of the magnetic shield is usually soft magnetic alloy. The magnetic permeability of this type of material is greatly improved after stress annealing, and it also makes them very sensitive to stress and collision. Therefore, possible bumps and extrusions during installation and disassembly Such operations will lead to a decrease in the performance of the magnetic shield, thereby affecting the accuracy of the fiber optic gyroscope.

Contents of the invention

Purpose of the present invention: In order to reduce the sensitivity of the fiber optic gyroscope to the environmental magnetic field and improve the environmental adaptability of the fiber optic gyroscope, the present invention provides a magnetic shielding of the fiber optic gyroscope that is reusable, easy to install and disassemble, has good magnetic shielding performance, and strong environmental adaptability cover.

The device is composed of upper and lower magnetic shields, which surround the magnetically sensitive part of the optical fiber gyro optical path. The device can also be applied to other optical gyroscopes sensitive to magnetic fields, such as ring laser gyroscopes.

The present invention provides the following technical solutions: a magnetic shielding case for an optical fiber gyroscope, which includes an upper shielding case, a lower shielding case, a base, a skeleton, and an optical fiber ring, and the lower shielding case is composed of a lower shielding case bottom plate and a lower shielding case side wall , the middle of the lower shield bottom plate is provided with an assembly hole, and the lower shield side wall is annularly arranged on the assembly hole of the lower shield bottom plate; the upper shield includes an upper shield bottom plate, an upper shield outer ring, an upper shield The cover plate and the inner ring of the upper shielding cover, the middle of the upper shielding cover bottom plate is provided with an installation hole for the installation of the optical fiber ring, and the edge is provided with through holes for the assembly of the upper and lower shielding covers, and the upper shielding cover cover is provided in the middle. The thin-walled flat plate of the assembly hole, the outer ring of the upper shield is a thin-walled cylindrical structure, the upper end is connected with the bottom plate of the lower shield, the lower end is connected with the outer circumference of the cover plate of the upper shield, and the inner ring of the upper shield is also a thin-walled cylinder structure, The upper end is connected to the circumference of the assembly hole of the upper shield cover plate, and the lower end is installed and matched with the side wall of the lower shield cover; a cylindrical boss is processed on the base, and the diameter of the cylindrical boss matches the diameter of the central hole of the lower shield cover; The skeleton is a thin-walled cylindrical structure, the diameter of the inner ring matches the inner ring of the upper shielding cover, and the fiber ring is wound around the outer circumference.

Both the side wall of the lower shielding case and the inner ring of the upper shielding case are provided with matching grooves distributed in the circumference.

There are several flanges with through holes in the assembly hole of the cover plate of the upper shielding cover, and the through holes on the flanges are matched with the mounting columns on the cylindrical boss of the base.

Countersunk holes for matching installation are processed on the edge of the bottom plate of the lower shield and the edge of the base.

The bottom plate of the upper shielding case and the bottom plate of the lower shielding case are provided with through holes for matching installation.

After the installation is completed, the inner ring of the upper shield is located between the inner cylindrical surface of the gyroscope frame and the side wall of the lower shield, and the transition fit between the inner ring of the upper shield and the side wall of the lower shield is a transition fit or a transition within the elastic range of the magnetic shielding material. The cover plate of the upper shield, the inner ring of the upper shield, the side wall of the lower shield, the bottom plate of the lower shield, the bottom plate of the upper shield, and the outer ring of the upper shield will form a closed magnetic circuit.

The cover plate of the upper shield, the inner ring of the upper shield, the side wall of the lower shield, the bottom plate of the lower shield, the bottom plate of the upper shield, and the outer ring of the upper shield are all processed by a soft magnetic alloy plate with high magnetic permeability. And the corresponding distribution is welded into an upper shielding case and a lower shielding case.

The technical effect produced by the present invention: the upper and lower shields of the present invention are processed by soft magnetic alloy with high magnetic permeability, wherein the upper shield and the lower shield form a closed magnetic circuit perpendicular to the light propagation direction outside the optical fiber gyroscope optical path , to achieve high-performance magnetic shielding, and also to protect the fiber optic ring. Through processing tolerance control, the transition fit between the inner ring of the upper shield and the side wall of the lower shield or interference fit within the elastic range of the magnetic shielding material can be made to minimize the magnetic resistance between the two and prevent the two Collision occurs. At the same time, the optical fiber gyroscope magnetic shielding cover of the present invention only uses fasteners to complete the assembly of various parts during the assembly process, and does not use glue or welding. The assembly and disassembly of the shielding cover are simple and easy. In addition, almost no stress is introduced to the shield during the assembly and disassembly of the gyroscope, and the shield can still maintain a high magnetic shielding effect, so it has great practical application value.

Description of drawings

Fig. 1 is the cross-sectional view of the assembly of the fiber optic gyroscope magnetic shield of the present invention, wherein, 1-upper shield, 2-lower shield, 3-base, 4-skeleton, 5-optical fiber ring, 6-screw, 7-gyroscope cover .

Fig. 2 is an assembly top view of the fiber optic gyroscope magnetic shield of the present invention, in which 1-upper shield, 3-base, 6-screw, 7-gyroscope cover.

Fig. 3 is an assembly exploded view of the fiber optic gyroscope magnetic shielding cover of the present invention, wherein, 1-upper shielding cover, 2-lower shielding cover, 3-base, 4-skeleton, 5-optical fiber ring, 6-screw, 7-gyro cover Plate, 8-threaded hole, 9-countersink hole, 10-light hole.

Fig. 4 is a schematic diagram of the structure of the upper shield of the fiber optic gyroscope magnetic shield of the present invention, wherein 9 - countersunk hole, 10 - optical hole, 11 - bottom plate of the lower shield, 12 - side wall of the lower shield.

Fig. 5 is a structural schematic diagram of the lower shielding cover of the fiber optic gyroscope magnetic shielding cover of the present invention, wherein, 10-light hole, 13-upper shielding cover bottom plate, 14-upper shielding cover outer ring, 15-upper shielding cover cover plate, 16-upper shielding cover inner circle.

Detailed ways

The present invention will be described in further detail below by means of specific embodiments:

Please refer to FIGS. 1-5 at the same time. The fiber optic gyroscope magnetic shield of the present invention includes an upper shield 1 , a lower shield 2 , a base 3 , a skeleton 4 , an optical fiber ring 5 and a gyroscope cover 7 .

The lower shielding case 2 is composed of a lower shielding case bottom plate 11 and a lower shielding case side wall 12 . As shown in Figure 4, the bottom plate 11 of the lower shielding case is provided with mounting holes in the middle, and the edge is provided with a number of stamping counterbores 9 for fixing the lower shielding case 2 and the base 3, and a number of through holes for assembling the upper and lower shielding cases. hole 10. The lower shield side wall 12 is annularly arranged on the mounting hole of the lower shield bottom plate 11 , and a set of grooves is processed on the lower shield side wall 12 to prevent the lower shield side wall 12 from interfering with the skeleton 4 . During actual processing, the bottom plate 11 of the lower shield and the side wall 12 of the lower shield are firstly machined out of shape, and then the diameter of the side wall 12 of the lower shield is machined to the tolerance range by bending, and then the shape is fixed by welding. Finally, the side wall 12 of the lower shielding case is welded to the bottom plate 11 of the lower shielding case to complete the processing of the lower shielding case 2, so as to reduce processing cost and material waste.

The upper shield 1 is also processed by welding thin plate materials. Referring to FIG. 5 , the upper shield 1 includes an upper shield bottom plate 13 , an upper shield outer ring 14 , an upper shield cover 15 , and an upper shield inner ring 16 . The middle of the upper shield bottom plate 13 is provided with an installation hole matching the fiber ring, and the edge is provided with through holes 10 for the upper and lower shields. The upper shield cover plate 15 is a thin-walled flat plate with a mounting hole in the middle, and a flange 17 is arranged in the mounting hole. The outer ring 14 of the upper shielding case has a thin-walled cylindrical structure, the upper end is connected with the bottom plate of the lower shielding case, and the lower end is connected with the outer circumference of the upper shielding case cover plate 15 . The inner ring 16 of the upper shielding case is also a thin-walled cylindrical structure, the upper end is connected with the circumference of the mounting hole of the upper shielding case cover plate 15, and the lower end is provided with a group groove whose shape and position match the grooves on the side wall of the lower shielding case. During actual processing, first process the shape of the part, then process the diameters of the upper shield outer ring 14 and the upper shield inner ring 16 to within the tolerance range by bending, and then weld the shape to fix it. Finally, the upper shield outer ring 14 and the upper shield inner ring 16 are welded with the upper shield bottom plate 13 and the upper shield cover plate 15 to complete the upper shield 1 processing.

The base 3 is an oil cylindrical boss processed on a square plate, and the diameter of the cylindrical boss matches the diameter of the central hole of the lower shield. Moreover, the edge of the base is processed with a countersunk hole 9 , and threads are processed in the hole, and the countersunk hole 9 processed on the lower shield 2 can just be installed in the countersunk hole 9 of the base 3 .

The frame 4 is equipped with a thin-walled cylindrical structure with flanges, the diameter of its inner ring matches the inner ring of the upper shield, and each flange is processed with a through hole 18 for connecting with the cylindrical boss of the base assembly. The optical fiber is encircled on the outer circumference of the frame and encapsulated by the outer ring of the upper shielding case. The gyro cover 7 is a circular plate arranged on the outer end of the upper shield cover for sealing and fixing.

After the parts are installed, the inner ring of the upper shield is just located between the inner cylindrical surface of the gyroscope frame and the side wall of the lower shield, and the transition fit between the inner ring of the upper shield and the side wall of the lower shield is the elastic range of the magnetic shielding material. The interference fit inside ensures the minimum reluctance of the closed magnetic circuit, and also prevents collision between the inner ring of the upper shield and the side wall of the lower shield. The upper shield cover plate, the upper shield inner ring, the lower shield side wall, the lower shield base plate, the upper shield base plate, and the upper shield outer ring will form a closed magnetic circuit like this. The closed magnetic circuit just surrounds the magnetically sensitive part in the optical path of the fiber optic gyroscope. After the ambient magnetic field passes through the magnetic circuit, the magnetic induction intensity is attenuated to a certain extent, so the error generated by the ambient magnetic field in the gyroscope output is also correspondingly reduced.

The upper shielding cover and the lower shielding cover of the present invention surround the optical fiber ring to form a closed-loop magnetic circuit perpendicular to the light propagation direction; after the ambient magnetic field passes through the shielding cover, the magnetic induction intensity is attenuated, and the proportion of the magneto-optical effect in the output of the gyroscope is reduced. Gyro performance has been improved. The magnetic shield can be assembled only by fasteners, the assembly process is simple and easy, and it is also convenient for gyroscope debugging and repair, which reduces the probability of introducing stress to the magnetic shield material in the above process, so the magnetic shield can be maintained at a high level The magnetic permeability and the attenuation effect on the environmental magnetic field are obvious. The upper shield and the lower shield can be welded with soft magnetic alloy sheets. Compared with mechanical processing, this method reduces the waste of expensive soft magnetic alloy materials in the processing process, shortens the processing cycle and reduces processing costs. . The magnetic circuit formed by the upper shield and the lower shield only surrounds the fiber ring and the frame, that is, only the part of the gyroscope that is sensitive to the magnetic field, rather than the entire gyroscope; in addition, the gyroscope base and frame are not processed with soft magnetic alloy materials , the outer ring of the upper shielding cover replaces the outer cover of the gyroscope, which reduces the amount of soft magnetic alloy material with a higher density, thereby reducing the weight of the gyroscope. value.

Claims (7)

1. A fiber optic gyroscope magnetic shield, characterized in that: it includes an upper shield (1), a lower shield (2), a base (3), a skeleton (4), an optical fiber ring (5), and the lower shield The cover (2) is composed of the lower shield bottom plate (11) and the lower shield side wall (12), the lower shield bottom plate (11) is provided with an assembly hole in the middle, and the lower shield side wall (12) is ring-shaped On the assembly hole of the bottom plate of the lower shield (11); the upper shield (1) includes the bottom plate of the upper shield (13), the outer ring of the upper shield (14), the cover plate of the upper shield (15), the upper shield The inner ring (16), the middle of the upper shield bottom plate (13) is provided with a mounting hole for the installation of the optical fiber ring, and the edge is provided with a through hole (10) for the upper and lower shield assembly, the upper shield cover plate (15 ) is a thin-walled flat plate with an assembly hole in the middle, the outer ring of the upper shield (14) has a thin-walled cylindrical structure, the upper end is connected with the bottom plate of the lower shield, and the lower end is connected with the outer circumference of the upper shield cover (15), The inner ring (16) of the upper shielding case is also a thin-walled cylindrical structure, the upper end is connected to the circumference of the assembly hole of the upper shielding case cover (15), and the lower end is fitted with the side wall of the lower shielding case; the base (3) is processed with a cylindrical Boss, the diameter of the cylindrical boss matches the diameter of the central hole of the lower shield; the skeleton (4) is a thin-walled cylindrical structure, the diameter of its inner ring matches the inner ring of the upper shield, and the optical fiber is wound around the outer circumference ring. 2. The fiber optic gyroscope magnetic shield according to claim 1, characterized in that: the side wall (12) of the lower shield and the inner ring (16) of the upper shield are both provided with matching grooves distributed in a circle. 3. The optical fiber gyro magnetic shield according to claim 2, characterized in that: there are several flanges with through holes in the assembly hole of the cover plate of the upper shield, and the through holes on the flange are connected with the cylindrical boss of the base Match the mounting posts on the 4. The fiber optic gyroscope magnetic shield according to claim 3, characterized in that: the edge of the bottom plate of the lower shield 2 and the edge of the base 3 are processed with countersunk holes for matching installation. 5 . The optical fiber gyroscope magnetic shield according to claim 4 , wherein the bottom plate of the upper shield case and the bottom plate of the lower shield case are provided with through holes for matching installation. 6 . 6. The optical fiber gyro magnetic shield according to any one of claims 1 to 5, characterized in that: after the installation is completed, the inner ring of the upper shield is located between the inner cylindrical surface of the gyro skeleton and the side wall of the lower shield, and the upper shield The transition fit between the inner ring of the cover and the side wall of the lower shielding case or the interference fit within the elastic range of the magnetic shielding material, the cover plate of the upper shielding case, the inner ring of the upper shielding case, the side wall of the lower shielding case, and the lower shielding case The bottom plate, the bottom plate of the upper shielding case and the outer ring of the upper shielding case will constitute a closed magnetic circuit. 7. The optical fiber gyroscope magnetic shield according to claim 6, characterized in that: the upper shield cover plate, the upper shield inner ring, the lower shield side wall, the lower shield bottom plate, the upper shield bottom plate, the upper shield The outer rings of the shields are all processed from high-permeability soft magnetic alloy plates, and are distributed and welded into upper shields and lower shields correspondingly.

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