Torque sensor

Claim 2

A torque sensor, comprising: a non-magnetic drive shaft coupled between a source of torque and a load, said drive shaft including a cylindrical outer surface; a magnetic layer rigidly affixed to said cylindrical surface of said drive shaft; and electric coil means located adjacent to said cylindrical surface of said drive shaft and said magnetic layer for detecting changes in the permeability of said magnetic layer produced by torque applied to said drive shaft.

Claim 3

The torque sensor as recited in Claim 1, which further comprises: processing circuit means coupled to said electric coil means for converting said changes in the permeability of said magnetic layer into an electrical signal representative of the torque applied to said drive shaft.

Claim 4

The torque sensor as recited in Claim 1, wherein: said magnetic layer is formed by wrapping a thin elongated ribbon of magnetic material about said cylindrical surface of said drive shaft, said ribbon forming a helical winding about said cylindrical surface, each turn of said helical winding being positioned at a-45 degree angle with respect to the longitudinal axis of said drive shaft.

Claim 5

The torque sensor as recited in Claim 1, wherein: said magnetic layer is formed by wrapping said cylindrical surface of said drive shaft with a plurality of parallel thin elongated ribbons of magnetic material, said plurality of ribbons forming a plurality of parallel helical windings about said cylindrical surface, each turn of said plurality of helical windings being positioned at a 45 degree angle with respect to the longitudinal axis of said drive shaft.

Claim 6

The torque sensor as recited in Claim 1, wherein said magnetic layer comprises: a plurality of their elongated segments of magnetic material affixed to said cylindrical surface of said drive shaft, each of said elongated segments being positioned such that the longitudinal axis of each segment forms a 45 degree angle with the longitudinal axis of said shaft.

Claim 7

The torque sensor as recited in Claims 3, 4 or 5, wherein: said magnetic material is a magnetically soft amorphous metal material.

Claim 8

The torque sensor as recited in Claim 2, wherein said electric coil means comprises: a single cylindrical pick-up coil having a longitudinal axis which is colinear with the longitudinal axis of said drive shaft.

Claim 9

The torque sensor as recited in Claim 2, wherein said electric coil means comprises: first and second cylindrical pick-up coils, each of said pick-up coils have a longitudinal axis which is colinear with the longitudinal axis of said drive shaft.

Claim 10

The torque sensor as recited in Claim 7, wherein said processing circuit means comprises: oscillator means for generating an AC switching signal; electronic switch means coupled in series with a source of DC power and said single pick-up coil for controlling the flow of current from said DC power source through said single pick-up coil, said current being proportional to the permeability of said magnetic layer, said electronic switch means being controlled by said AC switching signal from said oscillator means; and detector means coupled to said single pick-up coil for detecting the flow of current through said coil and for producing said electrical signal representative of said torque applied to said drive shaft.

Claim 11

The torque sensor as recited in Claim 8, wherein said processing circuit means comprises: oscillator means for generating an AC switching signal; first electronic switch means coupled in series with a source of DC power and said first pick-up coil for controlling the flow of a first current through said first pick-up coil, said first current being proportional to the permeability of said magnetic layer, said first electronic switch means being controlled by said AC switching signal from said oscillator means; second electronic switch means coupled in series with said DC power source and said second pick-up coil for controlling the flow of a second current through said second pick-up coil, said second current being proportional to the permeability of said magnetic layer, said second electronic switch means being controlled by said AC switching signal from said oscillator means; and detector means coupled to said first and second pick-up coils for detecting said first and second currents and for converting said detected currents into said electrical signal representative of said torque applied to said drive shaft.