Circularly magnetized non-contact torque sensor and method for measuring torque using same
First Claim
1. A magnetoelastic torque sensor for providing an output signal indicative of the torque applied to a member about an axially extending axis, of said member, comprising:
- a magnetoelastically active element directly or indirectly attached to/or forming a part of the surface of said member in such a manner that torque applied to said member is proportionally transmitted to said element;
said magnetoelastically active element being endowed with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis and comprising two or more axially distinct, magnetically contiguous circumferential regions which are oppositely magnetically polarized in a circumferential direction, whereby, when torque is applied to said member, said magnetoelastically active element produces a magnetic field varying with said torque; and
magnetic field sensor means mounted proximate to said magnetoelastically active element and oriented with respect thereto to sense the magnitude of said magnetic field and provide said output signal in response thereto.
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Accused Products
Abstract
A torque sensor comprises a magnetoelastically active element, and a magnetic sensor, such as a Hall effect sensor, responsive to the field of the magnetoelastically active portion. In one embodiment, the magnetoelastically active portion comprises a ring of material endowed with an effective uniaxial magnetic anisotropy such that the circumferential direction is the easy axis, and magnetically polarized in a substantially circumferential direction. The ring is attached to the torqued member, such as a rotating shaft, so that application of a torque to the shaft is transmitted to therting. The torque on the ring reorients the circumferential magnetic orientation of the ring, producing a helical magnetic orientation having both circumferential and axial components. A magnetic field vector sensor is mounted in a fixed position relative to the ring and oriented so that it responds maximally only to the field due to the axial magnetization components of the ring. The output of the sensor is thus proportional to the change in orientation of the magnetization resulting from torque applied to the shaft and transmitted to the ring. In another embodiment, the magnetoelastically active portion includes two or more axially distinct, magnetically contiguous, oppositely polarized circumferential regions. The regions may comprise physically separate rings or may be formed onto a single ring.
148 Citations
59 Claims
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1. A magnetoelastic torque sensor for providing an output signal indicative of the torque applied to a member about an axially extending axis, of said member, comprising:
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a magnetoelastically active element directly or indirectly attached to/or forming a part of the surface of said member in such a manner that torque applied to said member is proportionally transmitted to said element; said magnetoelastically active element being endowed with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis and comprising two or more axially distinct, magnetically contiguous circumferential regions which are oppositely magnetically polarized in a circumferential direction, whereby, when torque is applied to said member, said magnetoelastically active element produces a magnetic field varying with said torque; and magnetic field sensor means mounted proximate to said magnetoelastically active element and oriented with respect thereto to sense the magnitude of said magnetic field and provide said output signal in response thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of sensing a torque applied to a torqued member extending in an axial direction, comprising the steps of:
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(a) providing a magnetoelastically active element endowed with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis;
said element comprising two or more axially distinct, magnetically contiguous circumferential regions which are oppositely magnetically polarized in a circumferential direction, said element being directly or indirectly attached to or forming part of the surface of said torqued member such that torque applied to the member is proportionally transmitted to said element;(b) producing a magnetic field as a consequence of the application of torque to said member; and (c) sensing the magnitude of the magnetic field at a position proximate to said magnetoelastically active element as an indication of the magnitude of the torque applied to said member. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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58. A transducing ring adapted to be attached directly or indirectly on the surface of a member to which a torque is applied about an axis extending axially thereof in such a manner that torque applied to said member is proportionally transmitted to said ring, said ring comprising a magnetoelastically active element which is endowed with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis, said element comprising two or more axially distinct, magnetically contiguous circumferential regions which are oppositely magnetically polarized in the circumferential direction and having, when no torque is applied to said member, a circumferential magnetic orientation having only a circumferential component and, when a torque is applied to said member, a helical magnetic orientation having both circumferential and axial components, said ring producing a magnetic field varying with the torque applied to said member.
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59. A method of producing a magnetoelastic torque transducer for attachment to a member to which an axial torque is applied, comprising the steps of:
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(a) constructing a transducer from ferromagnetic, magnetostrictive material; (b) endowing said transducer with an effective uniaxial magnetic anisotropy having the circumferential direction as the easy axis; and (c) magnetically polarizing the transducer to form two or more axially distinct, magnetically contiguous circumferential regions which are oppositely magnetically polarized in a circumferential direction.
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Specification