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US 4,064,451 AGranted
Hysteresis compensated reed switch assembly for a position indicating system
AssigneeDiamond Power Specialty Corporation
InventorMilton Kearney Foxworthy
Life of this patent
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AssigneeDiamond Power Specialty Corporation
InventorMilton Kearney Foxworthy
Estimating the term…
The position of a control rod located within a nuclear reactor is sensed by a position indicating system utilizing low hysteresis reed switch assemblies. Each reed switch assembly includes a reed switch having an alternating magnetic flux field applied thereto through a coil surrounding the reed switch and energized by an alternating current power source. The amplitude of the alternating magnetic flux field is adjusted to be between a first flux level required to close the reed switch and a second flux level required to open the reed switch. The level of the alternating magnetic flux field is preset to be below the second flux level to maintain the switch in the open position until an external flux field is introduced to raise the total flux level above the first flux level to actuate the reed switch to close. The interaction of the alternating and external flux fields negates the hysteresis band of ordinary reed switches and provides a more sensitive and accurate position indicating circuit.
A position indicating system for determining the position of a movable member inside a sealed container comprising:
A low hysteresis reed switch assembly for position indicating systems having a magnetic member producing an external magnetic flux and movable in a sealed container comprising:
A method of minimizing hysteresis between reed switch actuation and deactuation in position indicating systems comprising the steps of:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring…:…
One conductor or channel: with magnetically controlled switches, e.g. by movement of a magnet
Energy generation of nuclear origin: nuclear fission reactors
Nuclear reactors
Term ended 20 Dec 1994 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to position indicating systems generally and particularly to position indicating circuits for indicating the position of a nuclear reactor control rod.
2. Description of the Prior Art
FIG. 1 is a schematic representation of the position indicating system of the present invention.
FIG. 2 is a blow up of one of the hysteresis compensated reed switches of the FIG. 1 system.
FIG. 3 is a graphic representation of reed switch conditions as the permanent magnet moves by the reed switch.
Referring now to the drawings, FIG. 1 depicts a permanent magnet 10 which is connected to a leadscrew extension 12 of a control rod (not shown) to be movable inside a sealed reactor housing 14 with the control rod. The control rod is moved by any well known drive means such as hydraulic jacks, roller nuts, pistons, etc. along a predetermined length L defining positions between full insertion of the control rod in the housing 14 and full withdrawal of the control rod from the housing 14.
The permanent magnet 10 sets up a field of localized magnetic flux which extends through a nonmagnetic wall 16 of the nuclear reactor housing 14 and actuates a reed switch in the area of the permanent magnet 10. The sealed integrity of the reactor housing 14 is thereby maintained. Mounted externally along the predetermined length L of the reactor housing 14 along a 2 inch spacing are a series of 72 magnetic reed switches S.sub.1 through S.sub.72. The reed switches S.sub.1 through S.sub.72 are in close proximity to the wall 16 and are spaced to allow actuation of the reed switches S.sub.1 through S.sub.72 as the permanent magnet 10 moves along the length L.
The reed switches S.sub.1 through S.sub.72 are connected between seventy-two resistors R.sub.1 -R.sub.72 of substantially identical resistance which are series connected to form a seventy-two step voltage divider circuit 18. The voltage divider circuit 18 is connected to a 5 volt D.C. power supply P at one end and fractions of this supply voltage P may be conducted to an output meter M by closing appropriate reed switches S.sub.1 through S.sub.72. The spacing of the reed switches S.sub.1 through S.sub.72 is set up to prevent the actuation of two adjacent reed switches S by the permanent magnet 10.