Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
  • G01L3/02—Rotary-transmission dynamometers
  • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
  • G01L3/08—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving optical means for indicating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
  • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
  • G01D5/3473—Circular or rotary encoders
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • 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
  • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
  • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
  • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
  • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
  • G01D5/347—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells using displacement encoding scales
  • G01D5/34776—Absolute encoders with analogue or digital scales
  • G01D5/34792—Absolute encoders with analogue or digital scales with only digital scales or both digital and incremental scales
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
  • G01L5/12—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring axial thrust in a rotary shaft, e.g. of propulsion plants

Definitions

• the present invention relates generally to measuring devices and more particularly concerns a device for measuring the torque and thrust to which a rotating shaft is subjected.
• Such devices are suitable for measuring the mechanical properties of rotating shafts belonging for example to propulsion systems for ships, energy recovery systems in particular wind turbines, etc.
• These systems use at least one propeller which, depending on the case, can be a driving or receiving propeller coupled to a motor, or generator, by a shaft.
• Such a shaft also called a power transmission shaft, is generally cylindrical in shape with a circular section. It is therefore defined geometrically by its length and its diameter. We will speak of lateral surface, or cylindrical surface to define the exterior surface of the cylinder which is delimited at its ends by two plane circular bases parallel to each other.
• Measuring, in situ, the performance of a propulsion system is only possible by precisely measuring the torque and thrust, or axial force, applied to the shaft mechanically connecting the transmitter (the motor, or generator) to the receiver (the propeller).
• in situ we mean measurements which are carried out in the real operating environment of the shaft, that is to say: shaft under load and rotating.
• Thrust measurement sensors which measure the load (resisting torques) applied to the shaft, the thrust exerted on the shaft (strain gauges) or even the displacement by torsional deformation of the shaft.
• shaft rotating disks, acoustic strings, optical shifts or magnetic tape.
• Thrust measurement sensors are less common and are generally integrated into a dynamometer which is based on the same principle (deformation or displacement) but in a longitudinal direction of the shaft.
• the present invention provides a non-invasive, high precision, stable and low cost measurement solution.
• non-invasive solution we mean a solution which has no or very little impact on the measurement (transparency of the measurement means on the measurement itself) and which generates little or no specific transformation or adaptation of the environment, or site. , measurement. It does not require heavy or complicated equipment to set up to carry out the measurement.
• stable measurement we mean a measurement that remains reliable even in the event of intermittent loss of power to the power device.
• the first object of the present invention is a device for measuring the torsional torque and the thrust of a rotating cylindrical shaft subjected to resistant torques, comprising:
• each pattern comprising at least one marker encoding a determined absolute rotation angle x’ or x’+S;
• At least one second digital image capture means arranged fixedly opposite the second series of visual patterns delivering digital images of each pattern of the second series;
• - means for synchronous processing of images captured by the first and second image capture means configured to identify at least one marker x'+S in a pattern of the second series, in correspondence with a marker x of the first series on, or as close as possible to, at least the same reference line; said processing means being further configured to compare the value of the absolute angle of rotation encoded in the marker x'+S and its position T'+TT, with the value of the absolute angle of rotation encoded in the marker x ' of the second series and its position T', previously recorded in a calibration step in which no resistant torque is applied to the shaft, and deduce the torque from S and the thrust from from TT.
• the images are generally rectangular in shape; the reference line corresponding to the horizontal center line passing through the center of the images.
• a lateral edge of the images is chosen as a vertical reference edge to determine the position of the marker on, or as close as possible, to the reference line.
• the position of the marker in the image corresponds to a determined number of pixels between the reference line and a first pixel of the marker.
• the shaft being of cylindrical shape with circular section
• the first and second image capture means are arranged fixedly in the same plane tangential to the cylindrical surface of the shaft and respectively facing the first and second series of visual patterns.
• the first and second image capture means are high-speed cameras arranged tangentially to the tree, at a determined distance from the patterns so as to present a focal plane in the tangential plane of the patterns.
• the second object of the present invention is a measurement method implemented by the measuring device as described above, said method consisting of:
• the fourth object of the present invention is a propulsion system comprising a propeller mechanically coupled to a motor by a shaft; said system comprising a measuring device as described above.
• FIG. 1 illustrates a block diagram of a measuring device according to the invention
• FIG. 1 illustrates an example of coding band used by the measurement method implemented by the measuring device according to the invention.
• the present invention proposes a device for precise, real-time and simultaneous measurement of the torsional torque and the thrust of a rotating and loaded shaft (in the presence of resistant torques), using imaging means, or vision. , industrial. This measurement can be carried out occasionally at regular intervals or continuously for continuous monitoring of the performance of the propulsion system.
• the thrust to which a loaded shaft is subjected, at one end of the shaft, has the effect of compressing the shaft in its longitudinal direction.
• the tree therefore undergoes deformation or displacement in this direction.
• the torsional torque to which a shaft is subjected under load and which is maximum during the start-up phase of the rotation of the shaft, has the effect of deforming the cylindrical surface of the shaft in a direction of torsion.
• the device according to the invention uses these two types of deformation to measure “visually” and simultaneously the torsional torque and the thrust.
• the tree is a tree used for the propulsion of ships.
• it is cylindrical in shape with a constant circular section of radius R and determined length. Its diameter (2xR) is between 200 mm and 1000 mm.
• the rotation speed of the shaft is between 100 and 1000 rpm.
• a shaft 1 belonging to propulsion system 2 is represented with its longitudinal axis AA' extending horizontally along X.
• Shaft 1 transmits the power generated by an MOT motor, or generator, to a HEL load, notably a propeller.
• the thrust exerted on shaft 1, from left to right in the figure, is represented by an arrow P in the axial direction X.
• the direction of rotation of the shaft is shown in the figure by the arrow ROT.
• the measuring device implements first and second visual coding bands 3 and 4 respectively supporting first and second series of visual patterns 3i and 4i.
• the first and second bands 3 and 4 are fixedly attached to the cylindrical surface SC of the shaft 1, respectively around the first and second straight sections of the shaft 1, by gluing or other very slightly intrusive fixing process.
• bands 3 and 4 are in the form of rings of negligible thickness.
• the patterns 3i, 4i can be directly printed on the surface SC of the shaft 1 by a laser marking, screen printing or other process.
• the two bands 3 and 4 are identical: same width (along X) and same visual patterns 3i and 4i arranged in the same way on their respective bands 3 and 4.
• the first and second bands 3 and 4 are arranged on the tree 1 respectively, in the vicinity of the HEL propeller (represented on the left in the figure) and the MOT motor (represented on the right in the figure), being spaced axially (along X) by a determined length L.
• Each pattern 3i, 4i contains at least one marker encoding an absolute rotation angle, arranged so as to obtain a resolution of at least 1 degree when measuring the torque.
• Patterns 3i and 4i are of identical height and can be contiguous or evenly spaced from each other. Patterns can represent alphanumeric characters, geometric shapes, etc.
• the thrust P has the effect of deforming the shaft 1 in its axial direction the first coding band 3. This movement, symbolized by the arrow p, is quantified by a distance TT.
• the twisting torque which is applied to the shaft 1 has the effect of deforming the cylindrical surface SC of the shaft 1 in a twisting direction.
• This deformation symbolized by the arrow c , results in an angular displacement ⁇ of the surface SC of the shaft 1, a displacement which is undergone by the second coding strip 4 which is arranged on the MOT motor side.
• This angular displacement (torsion angle) ⁇ is quantified by a distance S (length of the arc).
• the measuring device further comprises two digital image capture means 5 and 6 arranged respectively opposite the two coding bands 3 and 4.
• the image capture means 5 and 6 are preferably high-speed cameras (speeds greater than 60 images/second) which are cameras generally used in industry for part inspection and/or process control. industrial. Each camera 5 and 6 is arranged fixedly and at a determined distance from the coding bands 3 and 4 so as to present a focal plane (plane of sharpness or focusing plane) in the same plane tangential to each of the coding bands 3 and 4. Each camera 5 or 6 is preferably equipped with a lighting source in the visual or infrared spectrum, IR (InfraRed), not shown.
• IR InfraRed
• the two cameras 5 and 6 are thus capable of capturing images of each of the patterns 3i and 4i of the two coding bands 3 and 4 during the rotation of the shaft 1.
• the two cameras 5 and 6 are synchronized by a synchronizer 10, so as to deliver their “synchronous” images to processing means 7 comprising image analysis means 8.
• a database 9 hosted in a memory or storage server is coupled to the processing means 7. This database 9 contains measurement data from a calibration phase described below.
• the synchronous processing means 7 reconstruct plane images of rectangular shape of the visual patterns 3i and 4i from the image sequences captured by the two cameras 5 and 6 during the rotation of the shaft 1 using the means (one or more calculators) for image analysis 8.
• the images IMG1-IMG4 captured by the first and second cameras 5 and 6 in a preliminary calibration phase (IMG1 and IMG2) and in an operating phase (IMG3 and IMG4) of the shaft 1 in a real operating configuration : shaft 1 rotating and under load.
• the IMG1-IMG4 images are generally rectangular in shape.
• the analysis method considers a horizontal MED midline as the horizontal reference line in the IMG1-IMG4 images.
• This horizontal reference line MED extends in the axial direction along X of shaft 1. It is used as a “reading cursor” of the absolute angle of rotation.
• the left lateral edge EDG of the IMG1-IMG4 images is chosen as the vertical reference line. It extends perpendicular to the horizontal reference line MED in the direction Y.
• the axial position along X of a coding strip 3 or 4 is calculated by the distance between the lateral edge (in the embodiment described: the left side edge) of the strip 3,4 and the side edge (in the embodiment described: left side edge) of the image.
• each pattern 3i of the first coding band 3 corresponds to one and the same pattern 4i of the second coding band 4.
• Each pattern 3i, 4i includes at least one marker, here, a marker x, x’, x’+S encoding an absolute rotation angle.
• the patterns 3i, respectively 4i are ordered vertically (along Y) on their respective bands 3 and 4.
• the patterns 3i, 4i extend horizontally (along X) across their respective bands 3 and 4.
• the calibration phase is carried out during installation of the measuring device.
• This calibration consists of synchronously recording the values of the absolute rotation angles (markers: x, x') for each pattern 3i and its corresponding pattern 4i as well as the axial positions T and T' (along X) of the left lateral edges of the bands 3 and 4 relative to the vertical reference line EDG, by rotating shaft 1 at least one complete turn in the direction of rotation ROT, without any load (no resisting torque) applied to shaft 1.
• the values of the measured absolute angles of rotation x' and positions T' are recorded in a database 9, in correspondence with the values of the absolute angles of rotation x and the respective positions T.
• the processing means 7 will be used by the processing means 7 during the measurement in real operating conditions, as reference values, to calculate the thrust and the torque applied to the shaft 1.
• the torque of torsion is obtained by calculating the difference S between the reading of the real value of the absolute rotation angle x'+S and the corresponding absolute rotation angle x', pre-recorded in the database 9 in correspondence with the value of the absolute rotation angle encoded in the x marker.
• the thrust is obtained by calculating the difference in position TT (displacement) between the actual reading of the position T'+TT of the marker x'+S and the corresponding position T', pre-recorded in database 9.
• images IMG3 and IMG4 correspond to the images captured respectively by cameras 5 and 6 after starting the MOT motor in real operating conditions (shaft 1 under load).
• the first camera 5, considered as the reference (or master) camera is used as a “reading key” for the measurement.
• the absolute rotation angle encoded by the marker x (IMG3) and read by the master camera 5, is used to search in the database 9 for the corresponding values of absolute rotation angle x' and position T', pre-recorded from the slave camera 6 during the calibration phase.
• the slave camera 6 renders an IMG4 image in which the pattern 4i which shares the horizontal reference line MED with the pattern 3i of the IMG3 image, supports a marker x'+S encoding the absolute rotation angle taking into account the angular offset S induced by the torque applied to shaft 1.
• the analysis of the images is carried out by the analysis means 8 from the images rendered by the cameras 5 and 6 with the reference frame as defined above: left lateral edge EDG, horizontal center line MED.
• the analysis process consists of locating markers in the image using one or more image recognition algorithms.
• a point of interest such as a marker can be represented by one or more pixels, or even less than one pixel, by sub-pixel interpolation from neighboring pixels making it possible to increase the resolution of the recognition and therefore the precision of the measurement.
• the dimensions (or size) of a specific marker can therefore be expressed in number of pixels in the image.
• a marker is a characteristic visual element belonging to a 3i or 4i pattern. There is at least one marker per pattern 3i, 4i. Each marker has a specific known shape and physical dimensions (or actual size). The markers are regularly spaced apart from each other by a determined distance and arranged at a determined distance from the lateral edges of their respective coding strips 3, 4. The analysis means 8 are therefore able to identify the markers as pixels of the image and to locate them to the nearest millimeter on the surface of their respective coding strips 3, 4. Each marker encodes a determined absolute angle of rotation of the corresponding strip 3, 4.
• the accuracy of absolute rotation angle calculation is increased by calculating the distance (pixel count calculation) between the horizontal reference line MED and the start of the marker and as the physical dimensions of the marker ( actual size of the markers) are known, the distance between the start of this marker and the edge of the coding strip is deduced by simple translation of the pixels of the image on the surface of the strip.
• the measurement method implemented by the measuring device according to the invention consists of:
• the patterns 3i and 4i respectively x-1, x, x+1 and x'-1, x' and x'+1, correspond to 2 cm, 3 cm and 4 cm (IMG3) and 4 cm, 5 cm and 6 cm (IMG4).
• the marker here corresponds to a millimeter (mm) which is an element of the pattern 3i and 4i (the centimeter).
• the precision of the measurement is therefore given by the interval between two successive markers, here the millimeter.
• the value of the code seen by the first camera 5 and interpreted by the analysis means 8 is here 2.8 cm.
• the torque applied to the shaft 1 induced an angular shift (absolute rotation angle) which is directly interpreted by the processing means 7 from the images (IMG4) captured by the camera 6.
• patterns and markers can be used by the device according to the invention and in particular patterns in the form of a sequence of bar codes, of identical size, and aligned, vertically (along Y).
• slave cameras can be used by being arranged at different locations along the tree, always facing their respective coding strips and synchronized to the “master” camera.
• the processing means 7 average the thrust and torque values obtained by each of the “slave” cameras.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Family Cites Families (6)

• 2022
  • 2022-03-16 FR FR2202304A patent/FR3133671B1/fr active Active
• 2023
  • 2023-03-15 EP EP23715421.6A patent/EP4493899A1/de active Pending
  • 2023-03-15 WO PCT/EP2023/056676 patent/WO2023175046A1/fr not_active Ceased

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