Bobbin for a magnetic sensor
First Claim
1. A magnetometer sensor for use in a borehole survey tool, comprising:
- (a) a bobbin made from a non-magnetic copper alloy having a magnetic permeability not greater than 1.001 , said alloy comprised of at least 60 percent and at least 9 percent nickel;
(b) a strip of magnetic metal alloy wrapped around said bobbin to form a magnetic core, said strip having two ends with one end joined to said bobbin;
(c) at least one excitation winding wrapped around said core; and
(d) at least one sense winding wrapped around said core and said excitation winding.
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Accused Products
Abstract
A magnetometer sensor is described for a borehole survey. The magnetometer features a bobbin made from a metal alloy such as copper-nickel, which has a very low magnetic permeability, on the order of 1.0001, which can be joined to a magnetic metal alloy, such as Permalloy, by welding, which can be treated by annealing at a temperature of 1500 degrees Fahrenheit and which has a thermal coefficient of expansion generally on the order of the magnetic alloy. In one particular embodiment, the magnetometer sensor comprises a strip of magnetic metal alloy wrapped around the aforesaid bobbin to define a magnetic core, one excitation winding wrapped around the core, a plastic frame for carrying the magnetic core and excitation winding and at least one sense winding wrapped around the frame, the core and the excitation winding.
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Citations
19 Claims
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1. A magnetometer sensor for use in a borehole survey tool, comprising:
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(a) a bobbin made from a non-magnetic copper alloy having a magnetic permeability not greater than 1.001 , said alloy comprised of at least 60 percent and at least 9 percent nickel; (b) a strip of magnetic metal alloy wrapped around said bobbin to form a magnetic core, said strip having two ends with one end joined to said bobbin; (c) at least one excitation winding wrapped around said core; and (d) at least one sense winding wrapped around said core and said excitation winding. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a magnetic survey instrument for use in a borehole, a sensor assembly comprising:
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(a) a generally ring-shaped bobbin made from a copper-nickel alloy having a magnetic permeability not greater than 1.0001, said alloy comprised of at least 60 percent copper and at least 9 percent nickel; (b) a thin, long strip of Square Permalloy-80 spirally wrapped around said bobbin with one end of said strip welded to said bobbin, to define a toroid having a plurality of overlying layers with the other end of said strip welded to the outermost of said layers and in close proximity to said one end; (c) one electrical conductor wrapped around said strip and said bobbin generally at right angles to said strip to define a first winding; (d) a plastic frame for carrying therein the structure formed by said toroid and said first winding; (e) another electrical conductor wrapped around said frame and two opposite portions of said toroid to define a second winding, the structure formed by said frame, said toroid, and said two windings defining a coil assembly; and (f) a high temperature thermal plastic housing having an internal opening, configured to carry said coil assembly, said housing further having at least one axial channel in communication with said opening for carrying the free ends of said windings. - View Dependent Claims (17, 18, 19)
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Specification