US4712432A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Torque sensor
Assignee: Aisin Corp
•
Filing: 1985-10-18
•
Granted: 1987-12-15
•
Expires: 2005-10-18
Abstract
Abstract A non-contacting, inductively coupled leakage flux torque sensor and method of measuring torque by determining the change in leakage flux at a surface discontinuity as a result of a torsion stress. Two identical, mirror image discontinuities are formed in a ferromagnetic member. The discontinuities may comprise sets of slots or ferromagnetic projections on facing end surfaces of the ferromagnetic member. As a result of torsional stress on the member, the discontinuities change shape and dimension or are displaced, resulting in a change in leakage flux. The change in leakage flux is detected by two differentially connected coils. A modulator-demodulator circuit provides a determination of torque as a function of the changed flux.
Inventors
- 👤 Peter A. Hochstein
- 👤 Nobuyuki Imai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:58
CPC Classifications
G; G01; G01L; G01L3/00; G01L3/02; G01L3/04; G01L3/10; G01L3/101; G01L3/105
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
184 words
A method of measuring torque in a ferromagnetic member comprising: providing a ferromagnetic member; forming at least two, identical sets of parallel slots in said ferromagnetic member, one of said sets of parallel slots being the mirror image of said other set so that said one set is reversed in orientation with respect to the central horizontal axis of said ferromagnetic member, each of said sets of slots placed at an angle of 60°-75° with respect to the central horizontal axis of said ferromagnetic member; establishing an induced current within said ferromagnetic member by induction from a first coil adjacent to said member thus creating an electrical excitation field for said ferromagnetic member thereby generating a known leakage flux at said slots; subjecting said ferromagnetic member to a torsional stress; measuring the change in leakage flux at each of said slots, caused by said torsional stress changing the dimensions of said slots, said change in leakage flux being measured by two differentially connected secondary coils, and measuring a changed phase and amplitude of said excitation field from the output signals of said secondary coils.
Claim 2
Independent Claim
184 words
A method of measuring torque in a ferromagnetic member comprising: providing a ferromagnetic member; forming at least two, identical sets of parallel slots in said ferromagnetic member, one of said sets of parallel slots being the mirror image of said other set so that said one set is reversed in orientation with respect to the central horizontal axis of said ferromagnetic member, each of said sets of slots placed at an angle of 60°-75° with respect to the central horizontal axis of said ferromagnetic member; establishing an induced current within said ferromagnetic member by induction from a first coil adjacent to said member thus creating an electrical excitation field for said ferromagnetic member thereby generating a known leakage flux at said slots; subjecting said ferromagnetic member to a torsional stress; measuring the change in leakage flux at each of said slots, caused by said torsional stress changing the dimensions of said slots, said change in leakage flux being measured by two differentially connected secondary coils, and measuring a changed phase and amplitude of said excitation field from the output signals of said secondary coils.
Claim 3
Dependent Claim
29 words
A method as recited in claim 1 further comprising the step of determining the torque on said ferromagnetic member as a function of said measured change in leakage flux.
Claim 4
Dependent Claim
30 words
A method as recited in claim 1 wherein the step of forming said slots further comprises making the depth of said slots at least 4 times greater than their width.
Claim 5
Dependent Claim
22 words
A method as recited in claim 1 wherein said step of providing a ferromagnetic member further comprises providing a tubular ferromagnetic member.
Claim 6
Dependent Claim
29 words
A method as recited in claim 4 wherein said step of forming said sets of slots comprises forming said slots completely through the wall of said tubular ferromagnetic member.
Claim 7
Independent Claim
172 words
A method of measuring torque in a ferromagnetic member comprising: providing a ferromagnetic member comprising two tubular adjacent sections having uniformly spaced, facing circumferential end surfaces; connecting one of said tubular adjacent sections to each of the input and output portions of a torsion carrying bar so that said circumferential end surfaces are facing each other; forming a series of cut out portions around the circumference of the facing end surfaces of said tubular adjacent sections; establishing an induced current within said ferromagnetic member by induction from a first coil adjacent to said member thus creating an electrical excitation field for said ferromagnetic member thereby generating a known leakage flux at said tubular adjacent sections subjecting said torsion carrying bar to a torisonal stress; measuring the change in leakage flux caused by said torsional stress displacing said tubular adjacent sections, said change in leakage flux being measured by two differentially connected secondary coils, and measuring a changed phase and amplitude of said excitation field from the output signals of said secondary coils.
Claim 8
Independent Claim
172 words
A method of measuring torque in a ferromagnetic member comprising: providing a ferromagnetic member comprising two tubular adjacent sections having uniformly spaced, facing circumferential end surfaces; connecting one of said tubular adjacent sections to each of the input and output portions of a torsion carrying bar so that said circumferential end surfaces are facing each other; forming a series of cut out portions around the circumference of the facing end surfaces of said tubular adjacent sections; establishing an induced current within said ferromagnetic member by induction from a first coil adjacent to said member thus creating an electrical excitation field for said ferromagnetic member thereby generating a known leakage flux at said tubular adjacent sections subjecting said torsion carrying bar to a torisonal stress; measuring the change in leakage flux caused by said torsional stress displacing said tubular adjacent sections, said change in leakage flux being measured by two differentially connected secondary coils, and measuring a changed phase and amplitude of said excitation field from the output signals of said secondary coils.
Claim 9
Dependent Claim
107 words
A torque sensor comprising: a ferromagnetic member having at least two discontinuities, said discontinuities positioned at an angle of 60°-75° with respect to the central horizontal axis of said ferromagnetic member; a primary coil for establishing an induced excitation current in said ferromagnetic member thereby generating a magnetic leakage flux at said discontinuities; two differentially connected secondary coils, a different one of said secondary coils for measuring the change in leakage flux at each of said discontinuities when a torsional stress is applied to said ferromagnetic member; and amplitude and phase means for deriving the amplitude and phase of the induced current output of said secondary coils.
Claim 10
Dependent Claim
107 words
A torque sensor comprising: a ferromagnetic member having at least two discontinuities, said discontinuities positioned at an angle of 60°-75° with respect to the central horizontal axis of said ferromagnetic member; a primary coil for establishing an induced excitation current in said ferromagnetic member thereby generating a magnetic leakage flux at said discontinuities; two differentially connected secondary coils, a different one of said secondary coils for measuring the change in leakage flux at each of said discontinuities when a torsional stress is applied to said ferromagnetic member; and amplitude and phase means for deriving the amplitude and phase of the induced current output of said secondary coils.
Claim 11
Dependent Claim
30 words
A torque sensor as recited in claim 7 wherein a different one of said secondary coils is adapted to be positioned adjacent each of the discontinuities in the ferromagnetic member.
Claim 12
Dependent Claim
24 words
A torque sensor as recited in claim 7 wherein said discontinuities each have a depth of at least 4 times greater than their width.
Claim 13
Dependent Claim
16 words
A torque sensor as recited in claim 7 wherein said ferromagnetic member comprises a tubular sleeve.
Claim 14
Dependent Claim
22 words
A torque sensor as recited in claim 10 wherein said discontinuities are slots formed completely through the wall of said tubular sleeve.
Claim 15
Dependent Claim
149 words
A torque sensor comprising: a ferromagnetic member comprising two distinct tubular adjacent sections having uniformaly spaced facing end surfaces; a torsion carrying bar,one of said tubular sections being connected to an input portion of a torsion carrying bar and the other of said tubular sections being connected to an output portion of said bar; a series of cut-out portions formed around the circumference of the facing end surfaces of said tubular adjacent sections; a primary coil for establishing an induced excitation current in said ferromagnetic member thereby generating a magnetic leakage flux between said sections; two differently connected secondary coils for measuring the change in leakage flux caused at said tubular adjacent sections when a torsional stress displacing said tubular adjacent sections is applied to said torsion carrying bar; and amplitude and phase means for deriving the amplitude and phase of the induced current output of said secondary coils.
Claim 16
Dependent Claim
149 words
A torque sensor comprising: a ferromagnetic member comprising two distinct tubular adjacent sections having uniformaly spaced facing end surfaces; a torsion carrying bar,one of said tubular sections being connected to an input portion of a torsion carrying bar and the other of said tubular sections being connected to an output portion of said bar; a series of cut-out portions formed around the circumference of the facing end surfaces of said tubular adjacent sections; a primary coil for establishing an induced excitation current in said ferromagnetic member thereby generating a magnetic leakage flux between said sections; two differently connected secondary coils for measuring the change in leakage flux caused at said tubular adjacent sections when a torsional stress displacing said tubular adjacent sections is applied to said torsion carrying bar; and amplitude and phase means for deriving the amplitude and phase of the induced current output of said secondary coils.
Claim 17
Dependent Claim
21 words
A torque sensor as recited in claim 12 further comprising ferromagnetic projections on facing end surfaces of said tubular adjacent sections.
References Cited (Backward Citations)
US2826064A
Cited
US3329012A
Cited
SU564147A1
Cited
SU667836A1
Cited
SU838448A1
Cited
US4356732A
Cited
US4356732B1
Cited
US4414855A
Cited
US4485682A
Cited
US4506554A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-14 | 1991-06-15 | 1991-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-14 | 1995-06-15 | 1995-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-14 | 1999-06-15 | 1999-12-15 | $7700.00 | Window Closed / Lapsed |