US4896544A — Magnetoelastic torque transducer

Claim 1

Independent Claim 224 words

A magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member, said member having a ferromagnetic and magnetostrictive region formed of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute, said transducer comprising: a pair of axially spaced-apart annular bands defined within said region, said bands having respectively symmetrical right and left hand helically directed residual stress created magnetic anisotropy of sufficiently large magnitude compared with the random magnetic anisotropy in said member that the contribution to total magnetic anisotropy of any random anisotropy is negligible, each said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length; means for applying a cyclically time varying magnetic field to said bands; means for sensing the change in permeability of said bands caused by said applied torque; and, means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member.

Claim 2

Dependent Claim 224 words

A magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member, said member having a ferromagnetic and magnetostrictive region formed of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute, said transducer comprising: a pair of axially spaced-apart annular bands defined within said region, said bands having respectively symmetrical right and left hand helically directed residual stress created magnetic anisotropy of sufficiently large magnitude compared with the random magnetic anisotropy in said member that the contribution to total magnetic anisotropy of any random anisotropy is negligible, each said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length; means for applying a cyclically time varying magnetic field to said bands; means for sensing the change in permeability of said bands caused by said applied torque; and, means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member.

Claim 3

Dependent Claim 34 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein each said band has at least one circumferential region which is free of residually unstressed areas over at least 80% of its circumferential length.

Claim 4

Dependent Claim 26 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said band has at least one continuous circumferential region which is free of residually unstressed areas.

Claim 5

Dependent Claim 51 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said alloy further includes from zero up to a useful quantity for imparting desired properties to said alloy of an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vanadium, hafnium, columbium, tantalum, tin, and combinations thereof.

Claim 6

Dependent Claim 139 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said region is formed of a thermally hardened steel alloy consisting essentially of the elements and proportions indicated by the general formula: FeC.sub.a M.sub.b Q.sub.c wherein: "M" is an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof; "Q" is an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vandadium, hafnium, columbium, tantalum, tin and combinations thereof; "a" indicates a carbon content of from 0.05 to 0.75 percent by weight; "b" indicates a content of element "M" at least sufficient to raise the magnetostriction of said alloy to at least 5 ppm absolute; and "c" indicates a content of element "Q" from zero to a useful quantity for imparting desired properties to said alloy.

Claim 7

Dependent Claim 21 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said region forms a part of the surface of said member.

Claim 8

Dependent Claim 21 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said region is rigidly affixed to the surface of said member.

Claim 9

Dependent Claim 31 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said region is formed of a steel alloy selected from the group consisting of through hardenable and case hardenable steel alloys.

Claim 10

Dependent Claim 31 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein the magnetic easy axes in said bands are oriented, respectively, at angles of ±20° -60° to the axis of said member.

Claim 11

Dependent Claim 40 words

A magnetoelastic torque transducer, as claimed in claim 1, wherein said region is formed of nickel maraging steel and said bands are defined and said residual stress-created magnetic anisotropy has been instilled within a mechanically soft portion of said region.

Claim 12

Dependent Claim 167 words

A magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member, said member having a ferromagnetic and magnetostrictive region, said transducer comprising: a pair of axially spaced-apart annular bands defined within a thermally hardened portion of said region, said bands having respectively symmetrical right and left hand helically directed residual stress created magnetic anisotropy instilled therein subsequent to thermal hardening of sufficiently large magnitude compared with the random magnetic anisotropy in said member that the contribution to total magnetic anisotropy of any random anisotropy is negligible, each said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length; means for applying a cyclically time varying magnetic field to said bands; means for sensing the change in permeability of said bands caused by said applied torque; and means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member.

Claim 13

Dependent Claim 167 words

A magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member, said member having a ferromagnetic and magnetostrictive region, said transducer comprising: a pair of axially spaced-apart annular bands defined within a thermally hardened portion of said region, said bands having respectively symmetrical right and left hand helically directed residual stress created magnetic anisotropy instilled therein subsequent to thermal hardening of sufficiently large magnitude compared with the random magnetic anisotropy in said member that the contribution to total magnetic anisotropy of any random anisotropy is negligible, each said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length; means for applying a cyclically time varying magnetic field to said bands; means for sensing the change in permeability of said bands caused by said applied torque; and means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member.

Claim 14

Dependent Claim 93 words

A magnetoelastic torque transducer, as claimed in claim 11, wherein said region is formed of a steel alloy selected from the group consisting of iron-nickel martensite hardenable and thermally hardened steel alloys characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 15

Dependent Claim 163 words

In a magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member including ferromagnetic, magnetostrictive means associated with said member for altering in magnetic permeability in response to the application of torque to said member, means for applying a magnetic field to said ferromagnetic magnetostrictive means, means for sensing the change in permeability caused by said applied torque, and means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member, the improvement comprising forming said ferromagnetic, magnetostrictive means from a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 16

Dependent Claim 163 words

In a magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member including ferromagnetic, magnetostrictive means associated with said member for altering in magnetic permeability in response to the application of torque to said member, means for applying a magnetic field to said ferromagnetic magnetostrictive means, means for sensing the change in permeability caused by said applied torque, and means for converting said sensed change in permeability to an electrical signal indicative of the magnitude of the torque applied to said member, the improvement comprising forming said ferromagnetic, magnetostrictive means from a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 17

Dependent Claim 51 words

A magnetoelastic torque transducer, as claimed in claim 13, wherein said alloy further includes from zero up to a useful quantity for imparting desired properties to said alloy of an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vanadium, hafnium, columbium, tantalum, tin, and combinations thereof.

Claim 18

Dependent Claim 140 words

A magnetoelastic torque transducer, as claimed in claim 13, wherein said means is formed of a thermally hardened steel alloy consisting essentially of the elements and proportions indicated by the general formula: FeC.sub.a M.sub.b Q.sub.c FeC wherein: "M" is an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof; "Q" is an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vandadium, hafnium, columbium, tantalum, tin and combinations thereof; "a" indicates a carbon content of from 0.05 to 0.75 percent by weight; "b" indicates a content of element "M" at least sufficient to raise the magnetostriction of said alloy to at least 5 ppm absolute; and "c" indicates a content of element "Q" from zero to a useful quantity for imparting desired properties to said alloy.

Claim 19

Dependent Claim 23 words

A magnetoelastic torque transducer, as claimed in claim 13, wherein said ferromagnetic, magnetostrictive means forms a part of the surface of said member.

Claim 20

Dependent Claim 23 words

A magnetoelastic torque transducer, as claimed in claim 13, wherein said ferromagnetic, magnetostrictive means is rigidly affixed to the surface of said member.

Claim 21

Dependent Claim 36 words

A magnetoelastic torque transducer, as claimed in claims 13, 16, or 17, wherein said ferromagnetic, magnetostrictive means is formed of a steel alloy selected from the group consisting of through hardenable and case hardenable steel alloys.

Claim 22

Dependent Claim 117 words

A magnetoelastic torque transducer, as claimed in claims 13, 16, or 17, wherein at least a portion of said ferromagnetic, magnetostrictive means is endowed with helically directed residual stress created magnetic anisotropy, at least one circumferential region of said portion being free of residually unstressed areas over at least 50% of its circumferential length, said applying means applying said magnetic field to said endowed portion and to an area of said member not so endowed, said sensing means sensing the permeability difference between said portion and said area resulting from the application of torque to said member, said converting means converting said sensed permeability difference to an electrical signal indicative of the magnitude of the applied torque.

Claim 23

Dependent Claim 37 words

A magnetoelastic torque transducer, as claimed in claim 19, wherein said portion is a thermally hardened portion of said ferromagnetic, magnetostrictive means, said residual stress-created magnetic anisotropy having been instilled in said portion subsequent to thermal hardening.

Claim 24

Dependent Claim 27 words

A magnetoelastic torque transducer, as claimed in claim 19, wherein said circumferential region is free of residually unstressed areas over at least 80% of its circumferential length.

Claim 25

Dependent Claim 26 words

A magnetoelastic torque transducer, as claimed in claim 19, wherein said portion has at least one continuous circumferential region which is free of residually unstressed areas.

Claim 26

Dependent Claim 93 words

A magnetoelastic torque transducer, as claimed in claims 13, 16, or 17, wherein said ferromagnetic, magnetostrictive means includes a pair of axially spaced-apart annular bands defined therewithin, said bands having respectively symmetrical right and left hand helically directed residual stress created magnetic anisotropy, each said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length, said applying means applying said magnetic field to said bands, said sensing means sensing the change in permeability of said bands caused by said applied torque.

Claim 27

Dependent Claim 34 words

A magnetoelastic torque transducer, as claimed in claim 23, wherein each said band has at least one circumferential region which is free of residually unstressed areas over at least 80% of its circumferential length.

Claim 28

Dependent Claim 27 words

A magnetoelastic torque transducer, as claimed in claim 23, wherein each said band has at least one continuous circumferential region which is free of residually unstressed areas.

Claim 29

Dependent Claim 31 words

A magnetoelastic torque transducer, as claimed in claim 23, wherein the magnetic easy axes in said bands are oriented, respectively, at angles of ±20° -60° to the axis of said member.

Claim 30

Dependent Claim 37 words

A magnetoelastic torque transducer, as claimed in claim 23, wherein said bands are defined within a thermally hardened portion of said means, said residual stress-created magnetic anisotropy having been instilled in said bands subsequent to thermal hardening.

Claim 31

Dependent Claim 139 words

A magnetoelastic torque transducer, as claimed in claim 23, wherein said means is formed of a thermally hardened steel alloy consisting essentially of the elements and proportions indicated by the general formula: FeC.sub.a M.sub.b Q.sub.c wherein: "M" is an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof; "Q" is an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vandadium, hafnium, columbium, tantalum, tin and combinations thereof; "a" indicates a carbon content of from 0.05 to 0.75 percent by weight; "b" indicates a content of element "M" at least sufficient to raise the magnetostriction of said alloy to at least 5 ppm absolute; and "c" indicates a content of element "Q" from zero to a useful quantity for imparting desired properties to said alloy.

Claim 32

Dependent Claim 135 words

In a method of sensing the torque applied to a member having ferromagnetic, magnetostrictive means associated therewith which includes the steps of applying a magnetic field to said ferromagnetic, magnetostrictive means, sensing the change in permeability caused by said applied torque and converting said sensed change in permeability to an electrical signal indicative of the magnitude of the applied torque, the improvement comprising forming said ferromagnetic, magnetostrictive means of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 33

Dependent Claim 135 words

In a method of sensing the torque applied to a member having ferromagnetic, magnetostrictive means associated therewith which includes the steps of applying a magnetic field to said ferromagnetic, magnetostrictive means, sensing the change in permeability caused by said applied torque and converting said sensed change in permeability to an electrical signal indicative of the magnitude of the applied torque, the improvement comprising forming said ferromagnetic, magnetostrictive means of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 34

Dependent Claim 49 words

A method, as claimed in claim 29, wherein said alloy further includes from zero up to a useful quantity for imparting desired properties to said alloy of an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vanadium, hafnium, columbium, tantalum, tin, and combinations thereof.

Claim 35

Dependent Claim 25 words

A method, as claimed in claim 29, wherein said steel alloy is selected from the group consisting of through hardenable and case hardenable steel alloys.

Claim 36

Dependent Claim 62 words

A method, as claimed in claim 29, wherein said ferromagnetic, magnetostrictive means is endowed with a pair of axially spaced-apart annular bands having respectively symmetrical right and left hand helically directed residual stress-created magnetic anisotropy, the permeability difference between the bands is sensed, and said sensed permeability difference is converted to an electrical signal indicative of the magnitude of the applied torque.

Claim 37

Dependent Claim 54 words

A method, as claimed in claim 32, wherein said ferromagnetic, magnetostrictive means is thermally hardened, at least within the region thereof wherein said bands are located, for imparting desirable mechanical properties to the material from which said region is formed and endowing said thermally hardened means with said bands having said residual stress-created anisotropy.

Claim 38

Dependent Claim 160 words

In a method of sensing the torque applied to a member having a ferromagnetic and magnetostrictive region including the steps of endowing at least a portion of said region with helically directed residual stress-created magnetic anisotropy, applying a cyclically time varying magnetic field to said portion and to an area of said member not so endowed, and sensing the permeability difference between said portion and said area resulting from the application of torque to said member, the difference being indicative of the magnitude of the applied torque, the improvement comprising forming said region of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 39

Dependent Claim 160 words

In a method of sensing the torque applied to a member having a ferromagnetic and magnetostrictive region including the steps of endowing at least a portion of said region with helically directed residual stress-created magnetic anisotropy, applying a cyclically time varying magnetic field to said portion and to an area of said member not so endowed, and sensing the permeability difference between said portion and said area resulting from the application of torque to said member, the difference being indicative of the magnitude of the applied torque, the improvement comprising forming said region of a thermally hardened steel alloy characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 40

Dependent Claim 49 words

A method as claimed in claim 34, wherein said alloy further includes from zero up to a useful quantity for imparting desired properties to said alloy of an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vanadium, hafnium, columbium, tantalum, tin, and combinations thereof.

Claim 41

Dependent Claim 48 words

A method as claimed in claim 34, wherein said portion is thermally hardened, at least where said portion is endowed with said magnetic anisotropy, for imparting desirable mechanical properties to the material from which said region is formed, and endowing said thermally hardened portion with said magnetic anisotropy.

Claim 42

Dependent Claim 161 words

In a method of sensing the torque applied to a member having a ferromagnetic and magnetostrictive region, including the steps of endowing a pair of axially spaced-apart annular bands within said region with respectively symmetrical right and left hand helically directed magnetic anisotropy, applying a cyclically time varying magnetic field to said bands, and sensing the permeability difference between said bands resulting from the application of torque to said member, the difference being indicative of the magnitude of the applied torque, the improvement comprising: thermally hardening said member, at least within said region, for imparting desirable mechanical properties to the material from which said region is formed; defining said bands at the surface of said thermally hardened member; and, endowing said bands with magnetic anisotropy by instilling a residual stress distribution in each band which is sufficiently extensive that at least one circumferential region within each band is free of residually unstressed areas over at least 50% of its circumferential length.

Claim 43

Dependent Claim 161 words

In a method of sensing the torque applied to a member having a ferromagnetic and magnetostrictive region, including the steps of endowing a pair of axially spaced-apart annular bands within said region with respectively symmetrical right and left hand helically directed magnetic anisotropy, applying a cyclically time varying magnetic field to said bands, and sensing the permeability difference between said bands resulting from the application of torque to said member, the difference being indicative of the magnitude of the applied torque, the improvement comprising: thermally hardening said member, at least within said region, for imparting desirable mechanical properties to the material from which said region is formed; defining said bands at the surface of said thermally hardened member; and, endowing said bands with magnetic anisotropy by instilling a residual stress distribution in each band which is sufficiently extensive that at least one circumferential region within each band is free of residually unstressed areas over at least 50% of its circumferential length.

Claim 44

Dependent Claim 33 words

A method, as claimed in claim 37, wherein said instilled residual stress distribution is sufficiently extensive that said region is free of residually unstressed areas over at least 80% of its circumferential length.

Claim 45

Dependent Claim 34 words

A method, as claimed in claim 37, wherein said instilled residual stress distribution is sufficiently extensive that each said band has at least one continuous circumferential region which is free of residually unstressed areas.

Claim 46

Independent Claim 94 words

A method, as claimed in claims 37, 38 or 39, wherein said region is formed of a steel alloy selected from the group consisting of iron-nickel martensite hardenable and thermally hardened steel alloys characterized by a substantially isotropic magnetostriction having an absolute value of at least 5 ppm and including from 0.05 to 0.75 percent by weight carbon and sufficient of an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof to raise said alloy magnetostriction value to said at least 5 ppm absolute.

Claim 47

Dependent Claim 49 words

A method as claimed in claim 40, wherein said alloy further includes from zero up to a useful quantity for imparting desired properties to said alloy of an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vanadium, hafnium, columbium, tantalum, tin, and combinations thereof.

Claim 48

Independent Claim 140 words

A method, as claimed in claims 37, 38 or 39, wherein said region is formed of a thermally hardened steel alloy consisting essentially of the elements and proportions indicated by the general formula: FeC.sub.a M.sub.b Q.sub.c wherein: "M" is an element selected from the group consisting of nickel, chromium, cobalt, titanium, aluminum, manganese, molybdenum, copper, boron, and combinations thereof; "Q" is an element selected from the group consisting of silicon, phosphorous, sulfur, nitrogen, selenium, tungsten, vandadium, hafnium, columbium, tantalum, tin and combinations thereof; "a" indicates a carbon content of from 0.05 to 0.75 percent by weight; "b" indicates a content of element "M" at least sufficient to raise the magnetostriction of said alloy to at least 5 ppm absolute; and "c" indicates a content of element "Q" from zero to a useful quantity for imparting desired properties to said alloy.

Claim 49

Dependent Claim 23 words

An internal combustion engine having a torque-carrying output member, said member including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 50

Dependent Claim 22 words

Power transmission means having a torque-carrying output member, said member including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 51

Dependent Claim 22 words

Fluid turbine means having a torque-carrying output member, said member including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 52

Dependent Claim 20 words

A weighing system including torque-carrying means, said means including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 53

Dependent Claim 36 words

A machine tool including means for causing relative rotation between a tool and a workpiece, said machine tool having a torque-carrying member, said member including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 54

Dependent Claim 37 words

A robotic device comprising mechanical means for performing work pursuant to pre-programmed or real time control instructions, said device having a torque-carrying member, said member including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 55

Dependent Claim 22 words

A vehicular steering system having torque-carrying shaft means, said means including a magnetoelastic torque transducer as claimed in claims 1 or 13.

Claim 56

Dependent Claim 36 words

A force measuring system including means for converting a sensed force to torque, a torque transducer connected for sensing said torque, said torque transducer comprising a magnetoelastic torque transducer as claimed in claims 1 or 13.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-01-29	1993-07-31	1994-01-30	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-01-29	1997-07-31	1998-01-30	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-01-29	2001-07-31	2002-01-30	$7700.00	Window Closed / Lapsed

Magnetoelastic torque transducer

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