# US 5,705,810 A · Laser optical torquemeter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,810 A - Document ID: US5705810A - Status: Granted - Kind: A - Application number: 08/566,119 - Filed: 1995-12-01 - Granted: 1998-01-06 - Earliest claimed: 1995-12-01 - Inventors: Qi Wang; Xiubao Huang - Web page: https://patentgrep.com/patent/US5705810A ## CPC - G01L 3/12: involving photoelectric means - G01B 11/16: for measuring the deformation in a solid, e.g. optical strain gauge - G01D 5/28: with deflection of beams of light, e.g. for direct optical indication (G01D5/40 takes precedence; {mechanical adjustment G01D5/264}) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR ## Abstract A device intended to measure the torque. transmitted by a rotating shaft S1. This device has no physical connection with measured shafts. It employs a laser beam S, S' and a retroreflector RM of which the plane mirrors M1 and M2 are mounted on the torsional shaft S4 and transfer shaft S5 respectively or any other optical system, and it displays the torsion or torque as a function of angular displacement of the laser beam S' It may be used to determine the torque of either stationary or rotating shafts. ## Claims ### Claim 1 Apparatus for measuring torque transmitted by a rotating shaft S1, that comprises: a sensing member S3 mechanically coupled axially with shaft S1 and shaft S2 through which torque is transmitted, said sensing member S3 comprising a torsional shaft S4 and a tubular transfer shaft S5 joined rigidly at one end and free to rotate with respect to each other at the other end wherein the transfer shaft S5 contains a window at the other end; a signal emitter 1 positioned facing the window on the sensing member S3 to emit a collimated laser beam S essentially perpendicular to the shaft S4; a signal reflector RM positioned on the other end of said sensing member S3 in the path of said signal S from said emitter reflecting the signal received from said emitter back to a signal receiver by a light beam S' essentially perpendicular to the shaft; a signal receiver positioned facing the window on the sensing member S3 to receive the signal S' reflected by said reflector RM and producing an electrical signal determined by the position at which the signal from said reflector impinges on said receiver, said signal receiver comprising a measurement receiver 6 generating a signal, which corresponds to the distance of a light beam incidence point A from a fixed reference point 0 in a measurement plane essentially perpendicular to the light beam S', whereby said signal indicates the relative angular displacement of the torsional shaft S4 with respect to the transfer shaft S5. ### Claim 2 (depends on 1) Apparatus as in claim 1, wherein said light emitter has a laser diode 2. ### Claim 3 (depends on 1) Apparatus as in claim 1, wherein said sensing member S3 comprising a torsional shaft S4 and a hollow transfer shaft S5 joined rigidly at one end and free to rotate with respect to each other at the other end at which a bearing is placed between S4 and S5 and a plane mirror M1 is attached to the torsional shaft S4 and another plane mirror M2 is attached to the transfer shaft S5 at essentially the same axial location at the free end of the sensing member S3 to form a retroreflector RM with the apex axis of the mirror system essentially parallel to the shaft S4. ### Claim 4 (depends on 1) Apparatus as in claim 1, wherein said measurement receiver 6 is a single axial or bi-axial, analog, photoelectric, semiconductor position detector. ### Claim 5 (depends on 1) Apparatus as in claim 1, wherein an optical system 5, which reduces the diameter of the light beam S' is connected in optical series with said measurement receiver 6. ### Claim 6 (depends on 1) Apparatus as in claim 1, wherein another optical system 4, which only allows the light of certain frequency to pass, is connected in optical series with said measurement receiver 6. ### Claim 7 (depends on 1) Apparatus as in claim 1, wherein said signals, generated by the measurement receiver 6, correspond to the rectangular coordinates (x,y) of the distance of the light beam incidence point A from a fixed reference point 0 in a measurement plane essentially perpendicular to the light beam S', whereby one of said signal axis lies within the plane perpendicular to shaft axis and said signals are used to indicate the relative angular displacement of the mirror M1 with respect to mirror M2. ### Claim 8 (depends on 1) Apparatus as in claim 1, in which the apex of said retroreflector lies parallel with respect to the shaft S1 or S2. ### Claim 9 Apparatus for measuring torque transmitted by a rotating shaft S1, that comprises: a sensing member S3 mechanically coupled axially with shaft S1 and shaft S2 through which torque is transmitted, said sensing member S3 comprising a torsional shaft S4 and a tubular transfer shaft S5 joined rigidly at one end and free to rotate with respect to each other at the other end wherein the transfer shaft S5 contains a window at the other end; a signal emitter 1 positioned facing the window on the sensing member S3 to emit a collimated laser beam S essentially perpendicular to the shaft S4; a signal reflector RM positioned on the other end of said sensing member S3 in the path of said signal S from said emitter reflecting the signal received from said emitter back to a signal receiver by a light beam S' essentially perpendicular to the shaft; a signal receiver positioned facing the window on the sensing member S3 to receive the signal S' reflected by said reflector RM and producing an electrical signal determined by the position at which the signal from said reflector impinges on said receiver, said signal receiver comprising a measurement receiver 6 generating a signal, which corresponds to the distance of a light beam incidence point A from a fixed reference point 0 in a measurement plane essentially perpendicular to the light beam S', whereby said signal indicates the relative angular displacement of the torsional shaft S4 with respect to the transfer shaft S5; a signal receiver TT housed in transducer T and facing the temperature target T1 on sensing member of S3 to receive emitted infrared radiation from the sensing member S3 at its operation temperature. ### Claim 10 (depends on 9) Apparatus as in claim 9, wherein said signal receiver TT is a non-contact infrared thermal couple.