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US 11,390,346 B2Granted
Shaft minimizing ellipticalization strain error
OwnerMichael Grassiinventor
Life of this patent
Estimating the term…
Abstract
A shaft characterized by its length to diameter ratio being less than about 1.75 having a drive connection at one end where the wall thickness of the shaft is selected to be thick enough to avoid ellipticalization strain error in torsional measurement of less than 5%. One specific application is for a crankset spindle that can be used to measure a cyclist right, left, and total leg torque.
Claims15
A first shaft for a torque transmitter, the first shaft having first end portion, a middle portion, and a second end portion, the first shaft being characterized in that:
- at least one end portion of the first shaft includes a flange as a drive connection to transmit torque to an associated torqued object,
- the first shaft's length to outside diameter ratio is less than 1.75,
- the first shaft's effective area moment of inertia is sufficient to carry a torque and a perpendicular force applied to at least one of the two end portions of the first shaft, and
- the first shaft's wall thickness is sized, at a location of the middle portion of the first shaft of strain measurement to constrain ellipticalization deformation arising from a perpendicular force applied to at least one of the two end portions of the first shaft and yield an error in torque strain measurement of less than about 5% when torsional strain is measured by a strain sensor disposed on the first shaft.
1 more element
A crankset spindle characterized by:
- a first shaft having first end portion, a middle portion, and a second end portion, at least one end portion of the first shaft including a flange as a drive connection and the other of the end portions including a means to transmit torque to an associated torqued object, the first shaft's length to outside diameter ratio is less than 1.75, the first shaft's effective area moment of inertia being sufficient to carry a torque and a perpendicular force applied to at least one of the two end portions of the first shaft, and the first shaft's wall thickness is sized, at a location of the middle portion of the first shaft of strain measurement to constrain ellipticalization deformation arising from a perpendicular force applied to at least one of the two end portions of the first shaft and yield an error in torque strain measurement of less than about 5% when torsional strain is measured by a strain sensor disposed on the first shaft;
- and
- a second shaft mechanically connected to the first shaft to transmit torque from the drive connection of the first shaft to the second shaft.
Dependencies are inferred from the claim text.