Torque measurement apparatus
First Claim
1. A torque transducer for measuring torque in a rotating shaft of the kind having a transducer region, for example a region storing a permanent magnetisation, in which a magnetic transducer field is established and at least one non-contacting sensor adjacent the transducer region to develop a torque-dependent signal, wherein in operation the shaft is subject to longitudinal flux generated by means external to the transducer region, characterised by a non-contacting sensor responsive to a component of said longitudinal flux to develop a signal representing the level of said longitudinal flux, and means responsive to the level-representing signal for said longitudinal flux and magnetically coupled to said shaft to generate a compensating flux to counteract said longitudinal flux at the transducer region.
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Accused Products
Abstract
Torque in a shaft (61) is detected by means of non-contacting sensors (23, 24) sensing a torque-dependent magnetic field emanated by an integral transducer region (64, 32) of the shaft (61) that is circumferentially or longitudinally magnetized. The shaft (61) is driven by a motor (63) and subject to a longitudinal magnetic field (60) which acts on interference field. In one implementation of the invention coils (L1, L2: L3, L4) are energized to provide a counteracting magnetic field to compensate the interference field (60).
42 Citations
10 Claims
- 1. A torque transducer for measuring torque in a rotating shaft of the kind having a transducer region, for example a region storing a permanent magnetisation, in which a magnetic transducer field is established and at least one non-contacting sensor adjacent the transducer region to develop a torque-dependent signal, wherein in operation the shaft is subject to longitudinal flux generated by means external to the transducer region, characterised by a non-contacting sensor responsive to a component of said longitudinal flux to develop a signal representing the level of said longitudinal flux, and means responsive to the level-representing signal for said longitudinal flux and magnetically coupled to said shaft to generate a compensating flux to counteract said longitudinal flux at the transducer region.
- 5. A torque transducer for measuring the torque in a rotating shaft which, in operation, has a longitudinal field extending therealong, wherein at least one sensor is placed in non-contacting fashion adjacent a portion of the shaft to sense and provide a signal dependent on a transverse component of flux arising from the longitudinal flux due to the torque in the shaft.
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7. A torque transducer for a rotating shaft comprising flux generating means for generating a magnetic flux extending longitudinally in a portion of the shaft, said flux generating means being magnetically coupled to said shaft at axially spaced locations between which said portion is situated, at least one sensor placed in non-contacting fashion adjacent said portion to provide a signal dependent on a transverse component of flux arising from the longitudinal flux in said portion due to the torque in the shaft,
said magnetic flux generating means being operable to generate an alternating magnetic field at a selected frequency, and said at least one sensor signal being processed by frequency selective means operable at said selected frequency to provide a signal representing torque in the shaft derived from said alternating magnetic field.
Specification