Optical waveguides – Accessories
Reexamination Certificate
1999-04-29
2001-07-10
Lee, John D. (Department: 2874)
Optical waveguides
Accessories
C385S147000, C356S460000
Reexamination Certificate
active
06259849
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
Not Applicable
REFERENCE REGARDING FEDERAL SPONSORSHIP
Not Applicable
REFERENCE TO MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fiber optic gyroscopes and, more particularly, to a temporary interconnection between gyroscope components prior to effecting a more durable connection between them.
2. Description of Related Art and Other Considerations
A fiber optic gyroscope of the type encompassed by the present invention typically comprises an assembly which includes, inter alia, an optical fiber coil wound on and secured to a spool, and magnetic shielding enclosing the fibers. Such magnetic shielding may include the spool itself and a cover secured to the spool to form a magnetically protective housing enclosing the coil. An outer or external shield is placed over this protective housing, further to enhance the magnetic shielding about the optical fiber coil. It is conventional to bond the spool and the outer shield together, through the intermediary of a spacer ring, to which the spool and the shield are bonded, to secure the two together. This assembly is then bolted to a support, such as an inertial instrument block. Because the attachment of the inner and outer shields to the spacer ring is of a generally permanent nature, such as by bonding or welding, it is difficult to dismantle the assembly, such as for rework or repair. Such rework occurs during early production, when it is needed to open the assembly, which can occur multiple times to repair minor failures.
In the above-described construction, the inner and outer shields are formed of a high magnetically permeable material, which is subjected to a stress annealing process to enhance and maximize the magnetic properties. The annealing process renders the shields generally malleable and, therefore, they are vulnerable to harm. As a consequence, they are strain and impact sensitive and, should the assembly be dropped, bent, dented or even mishandled, or slightly deformed, whether innocently or carelessly caused, the magnetic shielding properties will be compromised and, thus, the magnetic properties invariably will be deleteriously affected. Such mishandling or mishap can occur during the above-mentioned dismantling and disassembly, e.g., for repair and rework, when the bond joint must be broken between the inner shield and spool assembly and the outer shield. It has been estimated that such dropping, bending, denting, or mishandling causes about 10% of all assemblies, that is, the spools and their contained fiber optics and associated parts, to be irreparably damaged and, therefore, to need replacement.
SUMMARY OF THE INVENTION
These and other problems are successfully addressed and overcome by the present invention by replacing the relatively permanent bonding between the inner shield and spool assembly and outer shield with a temporary structural interconnection. After all rework and repair is completed, the assembly is bolted or otherwise secured to a support for long term attachment.
Specifically, the temporary interconnection is formed by a resilient latchable or clasping interengageable coupling between the intermediary spacer ring and, preferably, the spool. This latchable or clasping interengageable coupling prevents, or at a minimum resists, inadvertent disassembly effected by the temporary interconnection. The preferred coupling comprises an O-ring residing within and between annularly configured grooves in the respective spacer ring and spool. When the assembly is bolted or otherwise secured to a support, this more durable interconnection supersedes the temporary interconnection. In addition, the temporary interconnection effected by the O-ring performs several desirable functions. It centers the inner shield within the outer shield to establish a concentric relationship between the two, avoids a radial metal-to-metal contact therebetween, reduces vibratory inputs, and mitigates against chattering which otherwise would affect the transmission in the optical fibers.
Several advantages are provided thereby. Primarily, harm to the magnetic properties of the material of the shields is reduced to a minimum. Repair and rework is facilitated without damage to the parts. Labor costs for repair and rework are reduced. Manufacturing scrap is decreased, with corresponding savings in parts and materials. Performance is enhanced through maintaining concentricity between the spool and coil with respect to the outer shield.
Other aims and advantages, as well as a more complete understanding of the present invention, will appear from the following explanation of exemplary embodiments and the accompanying drawings thereof.
REFERENCES:
patent: 5168756 (1992-12-01), Hulsing, II
patent: 5486922 (1996-01-01), Cordova
patent: 5818590 (1998-10-01), Patterson
patent: 5846199 (1999-04-01), Mark et al.
Goldner Eric L.
McLean Thomas
Tweedy Michael J.
Lee John D.
Litton Systems Inc.
Song Sarah N.
Sternfels Lewis B.
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