Twice spin frequency rotating filter
First Claim
1. In a tuned inertial sensor having a shaft supported from a frame by at least one bearing for rotation about a spin axis at a predetermined spin speed and a sensitive element and a sensitive element support system coupling the sensitive element to the shaft so as to allow relative motion between the sensitive element and the shaft, apparatus for reducing the inertial sensor sensitively to twice spin speed angular vibrations comprising:
- a filter rotor means disposed substantially coaxial with said spin axis; and
spring suspension means for coupling said filter rotor to said shaft so as to rotate therewith, said spring suspension means being a means for allowing spring restrained rotation of said filter rotor with respect to said shaft about axes perpendicular to said spin axis, the combination of said filter rotor means and said spring suspension means being tuned so that one of the natural frequencies of said filter rotor about axes perpendicular to said spin axis is substantially equal to twice spin speed when said shaft and said filter rotor means are rotating at spin speed, said one of the natural frequencies of said filter rotor being uncaged and substantially undamped.
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Accused Products
Abstract
Apparatus for reducing the twice spin frequency vibration sensitivity of tuned inertial sensors by providing a twice spin frequency rotating filter thereon is disclosed. In accordance with the invention a rotating filter is supported on the shaft assembly of a tuned inertial instrument so as to rotate therewith at the spin speed. By tuning the combination of the filter rotor and the spring support thereof so as to have a natural frequency of twice sin frequency about axes perpendicular to the spin axis, the filter rotor, operating uncaged and substantially undamped, will absorb a large part of the twice spin frequency angular vibration torques imposed on the shaft assembly through bearing noise and other sources. Similarly in tuned instruments sensitive to twice spin frequency linear vibration, the filter rotor and spring suspension can be tuned so that the filter rotor has a translational natural frequency along axes perpendicular to the spin axis equal to twice spin frequency, thereby tending to absorb most of the twice spin frequency linear vibration forces imposed on the rotating system.
12 Citations
28 Claims
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1. In a tuned inertial sensor having a shaft supported from a frame by at least one bearing for rotation about a spin axis at a predetermined spin speed and a sensitive element and a sensitive element support system coupling the sensitive element to the shaft so as to allow relative motion between the sensitive element and the shaft, apparatus for reducing the inertial sensor sensitively to twice spin speed angular vibrations comprising:
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a filter rotor means disposed substantially coaxial with said spin axis; and spring suspension means for coupling said filter rotor to said shaft so as to rotate therewith, said spring suspension means being a means for allowing spring restrained rotation of said filter rotor with respect to said shaft about axes perpendicular to said spin axis, the combination of said filter rotor means and said spring suspension means being tuned so that one of the natural frequencies of said filter rotor about axes perpendicular to said spin axis is substantially equal to twice spin speed when said shaft and said filter rotor means are rotating at spin speed, said one of the natural frequencies of said filter rotor being uncaged and substantially undamped. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a tuned inertial sensor having a shaft supported from a frame by at least one bearing for rotation about a spin axis at a predetermined spin speed and a sensitive element support system coupling a sensitive element to the shaft so as to allow relative motion between the sensitive element and the shaft and to provide a predetermined axial pendulosity of the sensitive element, apparatus for reducing the inertial sensor sensitively to twice spin speed angular vibrations comprising:
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a filter rotor means disposed substantially coaxial with said spin axis; and spring suspension means for coupling said filter rotor means to said shaft so as to rotate therewith, said spring suspension means being a means for allowing spring restrained translation of said filter rotor means with respect to said shaft along axes perpendicular to said spin axis, the combination of said filter rotor means and said spring suspension means being tuned so that the translational natural frequency of said filter rotor along axes perpendicular to said spin axis is substantially equal to twice spin speed, said translational natural frequency of said filter rotor being substantially undamped. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. An inertial instrument comprising:
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a shaft means supported on bearings for rotation about a spin axis at a predetermined spin frequency; a rotor having first, second and third orthogonal principal axes, said third principal axis being approximately aligned with said spin axis, said rotor having substantially different moments of inertia about said first and second principal axes; a rotor suspension means for coupling said rotor to said shaft, said rotor suspension means having first and second torsional spring rates about first and second rotor suspension means axes respectively, said rotor having a predetermined pendulosity along said first principal axis with respect to the center of support of said suspension means; a filter rotor means disposed substantially coaxial with said spin axis; and filter rotor spring suspension means for coupling said filter rotor to said shaft so as to rotate therewith, said filter rotor spring suspension means being a means for allowing spring restrained rotation of said filter rotor with respect to said shaft about axes perpendicular to said spin axis, the combination of said filter rotor means and said filter rotor spring suspension means being tuned so that one of the natural frequencies of said filter rotor about axes perpendicular to said spin axis is substantially equal to twice spin speed when said shaft and said filter rotor means are rotating at spin speed, said one of the natural frequencies of said filter rotor being uncaged and substantially undamped, said filter rotor spring suspension means also being a means for allowing spring restrained translation of said filter rotor means with respect to said shaft along axes perpendicular to said spin axis, the combination of said filter rotor and said filter rotor spring suspension means being tuned so that the translational natural frequency of said filter rotor along axes perpendicular to said spin axis is substantially equal to twice spin speed, said translational natural frequency of said filter rotor being substantially undamped. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification