US 6,269,702 B1 · Method and apparatus for measuring torque

Abstract

A method and apparatus for measuring torque of a rotating shaft is provided. In one embodiment, the apparatus includes a transducer assembly that is attached to a shaft. The transducer assembly includes a first plate member, a plurality of webs extending from the first plate member and a second plate member connected to the webs. A plurality of strain gauges are mounted on the transducer assembly at selected locations and in selected patterns. As torque is applied to the shaft, the torsional load from the shaft causes stress in the first plate member, the web members, and the second plate member. The strain gauges measure this stress and generate signals that provide a measure of the stress. The signals transmitted from the sensing circuit are compared with calibration data, and the torque value is inferred. In one embodiment, the strain gauges are arranged in opposing pairs on the transducer assembly and electrically connected as a Wheatstone bridge, so that strain resulting from non-torsional loads is canceled from the measured signal, thereby improving torque measurement accuracy. In another embodiment, the strain gauges are located on thinned regions in the transducer assembly which are fashioned for the purpose of creating areas of localized high stress. In another embodiment, the transducer assembly includes a decoupling aperture. The decoupling aperture minimizes hysteresis due to warping and bending of the transducer assembly.

Claims20

Dependent claims

A transducer for sensing torque from a rotateable shaft comprising:

a first planar disk extending in a first plane and having a plurality of apertures therethrough so that said disk is adapted to be coupled to the rotateable shaft;
a first plurality of web members extending perpendicular from the first planar disk, in a direction away from said shaft;
a second planar disk coupled to the web members, the second planar disk extending in a plane parallel to the first planar disk;
a first plurality of pairs of strain gauges coupled to the second planar disk, one pair of strain gauges being positioned adjacent the coupling point between each web within the first plurality of webs and the second planar disk, with a first strain gauge within each pair being positioned on a first side of a web and a second strain gauge in the pair being positioned on an opposite side of the respective web;
a series electrical connection between each first strain gauge of each pair;
and
a series electrical connection between each second strain gauge of each pair.

4 more elements

A transducer for sensing torque from a rotateable shaft comprising:

a first planar disk extending in a first plane and having a plurality of apertures therethrough so that said disk is adapted to be coupled to the rotateable shaft;
a pair of web members extending perpendicular from the first planar disk, in a direction away from said shaft, the first web member in said pair being positioned at a mirror image location with respect the second web member in the pair about a central plane that is perpendicular to the first planar members and passes though the center of the first planar disk;
a second planar disk coupled to the pair of web members, the second planar disk extending in a plane parallel to the first planar disk;
a pair of strain gauges coupled to the second planar disk, one pair of strain gauges being positioned on the second planar disk adjacent the coupling point between each web and the second planar disk, with a first strain gauge within each pair being positioned on a first side of a web and a second strain gauge in the pair being positioned on an opposite side of the respective web;
a Wheatstone bridge circuit having four legs composed of the pairs of the strain gauges, with the first strain gauge of the first web of the pair being in a leg of the Wheatstone bridge opposite the first strain gauge of the second web of the pair and the second strain gauge of the first web being in a leg of the Wheatstone bridge opposite the second strain gauge of the second member of the web, the first and second strain gauges being in adjacent legs to each other.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for measuring torque

Life of this patent

Method and apparatus for measuring torque

Life of this patent

Abstract

Claims20