WEIGHT MACHINE SENSOR SYSTEM
A load sensor includes a bolt configured to support a pulley of a weight machine, and a strain gauge laminated onto an exterior surface of a shoulder section of the bolt.
1 . A load sensor comprising:
a bolt configured to support a pulley of a weight machine; and
a strain gauge laminated onto an exterior surface of a shoulder section of the bolt for sensing force applied by the pulley to the bolt.
2 . The load sensor of claim 1 , wherein the shoulder section includes a stress concentration geometry that axially overlaps the strain gauge, the stress concentration geometry being a recess extending circumferentially at least partially around an axis of the bolt;
wherein the bolt is configured to orient the strain gauge relative to the weight machine in a predetermined orientation, the bolt including an alignment feature that is a flat face of the shoulder section that mates with a corresponding alignment feature of a bracket of the weight machine, the corresponding alignment feature being a non-circular through-hole;
wherein the predetermined orientation includes the strain gauge being in one of tension or shear when the pulley is loaded.
3 . The load sensor of claim 1 , wherein the shoulder section includes a stress concentration geometry proximate the strain gauge.
4 . The load sensor of claim 3 , wherein the stress concentration geometry axially overlaps the strain gauge.
5 . The load sensor of claim 4 , wherein the stress concentration geometry is a recess extending circumferentially at least partially around an axis of the bolt.
6 . The load sensor of claim 1 , wherein the bolt is configured to orient the strain gauge relative to the weight machine.
7 . The load sensor of claim 6 , wherein the bolt includes an alignment feature the shaft to control orientation of the strain gauge relative to the weight machine, the alignment feature being a flat face of the shoulder section of the bolt.
8 . The load sensor of claim 7 , wherein the alignment feature of the bolt mates with a corresponding alignment feature of a bracket of the weight machine, the corresponding alignment feature being a non-circular through-hole that mates with the alignment feature of the bolt to control the orientation.
9 . The load sensor of claim 6 , wherein the bolt is configured to orient the load sensor with the strain gauge being in one of tension or shear when the pulley is loaded.