EP0422702A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Magnetoelastic torque transducer
Assignee: Mag Dev Inc
•
Filing: 1987-12-03
•
Granted: —
•
Expires: 2007-12-03
Abstract
Abstract A magnetoelastic torque transducer for providing an electrical signal indicative of the torque applied to a member, the member including ferromagnetic, magnetostrictive means affixed to, associated with or forming a part of the surface of the torqued member for altering in magnetic permeability in response to the application of torque to the member. The ferromagnetic, magnetostrictive means is advantageously formed of a thermally hardened or iron-nickel martensite hardenable 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 one or more elements selected from Ni, Cr, Co, Ti, Al, Mn, Mo, Cu and B to raise the alloy magnetostriction to at least 5 ppm absolute. Preferably, the ferromagnetic, magnetostrictive means is formed of nickel maraging steel. The transducer comprises a pair of axially spaced-apart annular bands defined within a region of the ferromagnetic, magnetostrictive means, the bands being endowed with residual stress created, respectively symmetrical right and left hand helically directed magnetic anisotropy of sufficiently large magnitude that the contribution to total magnetic anisotropy of any random anisotropy in the member is negligible. In one aspect of the invention, each said band has at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length. In another aspect of the invention, the alloy is thermally hardened before the bands are endowed with the residual stress-created magnetic anisotropy.
Inventors
- 👤 Ivan J. Garshelis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 08:49
CPC Classifications
G; G01; G01L; G01L3/00; G01L3/02; G01L3/04; G01L3/10; G01L3/101; G01L3/102; G01L3/103; G01L3/105
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
159 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 for altering in magnetic permeability in response to the application of torque to said member, at least one annular band defined within said region; means for applying a cyclically time varying magnetic field to said band, 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, said trandsucer characterized by said band having 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, said band having at least one circumferential region which is free of residually unstressed areas over at least 50% of its circumferential length.
Claim 2
Dependent Claim
113 words
A magnetoelastic torque transducer, as claimed in claims 1, wherein at least a portion of said ferromagnetic, magnetostrictive region 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 3
Dependent Claim
118 words
A magnetoelastic torque transducer, as claimed in claims 1, wherein said ferromagnetic, magnetostrictive region 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 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, said applying means applying a cyclically time varying magnetic field to said bands, said sensing means sensing the change in permeability of said bands caused by said applied torque.
Claim 4
Dependent Claim
27 words
A magnetoelastic torque transducer, as claimed in any one of the preceding claims, wherein said ferromagnetic, magnetostrictive region forms a part of the surface of said member.
Claim 5
Dependent Claim
27 words
A magnetoelastic torque transducer, as claimed in any one of the preceding claims, wherein said ferromagnetic, magnetostrictive means is rigidly affixed to the surface of said member.
Claim 6
Dependent Claim
40 words
A magnetoelastic torque transducer, as claimed in any one of claims 1-5, wherein said bands are defined within a thermally hardened portion of said region, said residual stress-created magnetic anisotropy having been instilled in said bands subsequent to thermal hardening.
Claim 7
Dependent Claim
34 words
A magnetoelastic torque transducer, as claimed in any one of claims 1-6, wherein the magnetic easy axes in said bands are oriented, respectively, at angles of ± 20°-60° to the axis of said member.
Claim 8
Dependent Claim
33 words
A magnetoelastic torque transducer, as claimed in any one of claims 1-7, wherein said at least one circumferential region is free of residually unstressed areas over at least 80% of its circumferential length.
Claim 9
Dependent Claim
30 words
A magnetoelastic torque transducer, as claimed in any one of claims 1-8, wherein said at least one circumferential region is free of residually unstressed areas over its entire circumferential length.
Claim 10
Dependent Claim
95 words
A magnetoelastic torque transducer, as claim in any one of claims 1-9, wherein said region is formed of a steel alloy selected from the group consisting of iron-nickel martensite hardenable and thermally hardened steel alloys exhibiting 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 11
Dependent Claim
54 words
A magnetoelastic torque transducer, as claimed in any one of claims 11, 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 12
Dependent Claim
145 words
A magnetoelastic torque transducer, as claimed in any one of the preceding claims, wherein said region is formed of a thermally hardened steel alloy consisting essentially of the elements and proportions indicated by the general formula: FeC a M b Qc 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 cinsisting 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 13
Dependent Claim
25 words
A magnetoelastic torque transducer, as claimed in any one of claims 10 or 11, wherein said region is formed of said thermally hardened steel alloy.
Claim 14
Dependent Claim
37 words
A magnetoelastic torque transducer, as claimed in any one of the preceding claims, wherein said ferromagnetic, magnetostrictive region is formed of a steel alloy selected from the group consisting of through hardenable and case hardenable steel alloys.
Claim 15
Dependent Claim
33 words
A magnetoelastic torque transducer, as claimed in any of claims 1-11, wherein said bands are defined and said residual stress-created magnetic anisotropy has been instilled within a mechanically soft portion of said region.
Claim 16
Dependent Claim
23 words
A magnetoelastic torque transducer, as claimed in any one of claims 10,11 or 15, wherein said region is formed of nickel maraging steel.
Claim 17
Dependent Claim
30 words
The use of a magnetoelastic torque transducer according to any one of the preceding claims for sensing the torque applied to said member having said ferromagnetic magnetostrictive means associated therewith.
Claim 18
Dependent Claim
25 words
The transducer according to any one of the claims 1 to 16 as a part of an internal combustion engine having a torque-carrying output member.
Claim 19
Dependent Claim
25 words
The transducer according to any one of the claims 1 to 16 as a part of a power transmission means having a torque-carrying output member.
Claim 20
Dependent Claim
25 words
The transducer according to any one of the claims 1 to 16 as a part of a fluid turbine means having a torque-carrying output member.
Claim 21
Dependent Claim
22 words
The transducer according to any one of the claims 1 to 16 as a part of a weighing system including torque-carrying means.
Claim 22
Dependent Claim
38 words
The transducer according to any one of the claims 1 to 16 as a part of a machine tool including means for causing relative rotation between a tool and a workpiece, said machine tool having a torque-carrying member.
Claim 23
Dependent Claim
39 words
The transducer according to any one of the claims 1 to 16 as a part of 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.
Claim 24
Dependent Claim
24 words
The transducer according to any one of the claims 1 to 16 as a part of a vehicular steering system having torque-carrying shaft means.
Claim 25
Dependent Claim
29 words
The transducer according to any one of the claims 1 to 16 as a part of a force measuring system including means for converting a sensed force to torque.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.