MXPA00003735A - Method for manufacture of optical torque transducers - Google Patents

Abstract

A method of manufacturing patterns on the surfaces of grating elements of a torque transducer having a shaft comprising first and second rigid torque input members connected by a torsional coupling enabling relative angular deflection between the first and second input members, first and second grating elements respectively associated with the first and second input members, the surfaces of the grating elements being adjacent to each other and able to relatively displace as a function of torque in the shaft, the method comprising the steps of:forming an assembly by rotationally and axially fixing the input members and respective grating elements to the torsional coupling;mounting the assembly in a machine comprising a radiation source arranged to irradiate regions of the surfaces of the grating elements whilst a relative angular displacement between the torque input members with respect to their zero torque alignment condition is maintained;and simultaneously irradiating regions of the surfaces of the grating elements whilst the angular displacement between the torque input members is maintained.

Description

METHOD FOR THE MANUFACTURE OF OPTICAL TORQUE TRANSDUCERS This invention relates to a method for the manufacture of optical torque transducers. Such torque transducers are used to measure the amount of torque in arrows, particularly rotating arrows such as, for example, those found in electrical steering systems in automotive applications. BACKGROUND OF THE INVENTION Electric steering systems conventionally incorporate an input arrow element, connected through a Hooke joint arrangement and an intermediate arrow towards the steering wheel. The input shaft therefore requires to rotate at an angle typically of one to two revolutions on both sides from the centered steering position. It is a requirement of the electric steering system to accurately measure the variable torque of its rotating shaft continuously. Torque conventionally applied to the arrow causes its angular deviation, said deviation causes a part of the arrow to move angularly relative to another part, and this displacement can be detected in order to provide a measurement of this torque . The detection device should allow rotation of the arrow, preferably using non-contact signal transmission means for reliability and simplicity. Said detection device includes reflective and aperture-based optical devices as well as magnetic devices such as magnetostrictive or variable reluctance connections. To improve the accuracy of said detection device, the torque transducer can incorporate an arrow assembly comprising two grid elements fixed or integrated into two torque input members joined by a connection that allows torsional deformation . When a torque is applied between the two torque input members, the connection allowing torsional deformation causes an increased relative angular displacement of the two grid elements which allows the use of a less sensitive detection device. This method relates to the manufacture of torque transducers employing reflective or transmissive optical detection devices, comprising grid patterns consisting of alternate regions of high and low reflectivity or transmissibility (respectively) for electromagnetic radiation (EMR). given incident. A high and low reflectivity includes variations in direct specular reflection and variations in diffuse reflection. The grid patterns are illuminated by a source of electromagnetic radiation, typically ultraviolet light, visible light, or infrared light, which are interrogated by one or more sets of detectors sensitive to electromagnetic radiation. The sets include Load Coupling Devices (CCD), Very Large Scale Integration Vision Chips (VLSI) as well as sets of one-dimensional or two-dimensional photodetectors. The output of one or more pattern interrogation sets can be processed in order to produce a measurement of the torque applied to the arrow. The regions of high and low reflectivity and transmissibility can be arranged axially or radially around the axis of rotation of the arrow and are of a nature such as to allow a continuous output of the assemblies irrespective of the angular position of the arrow, since the dimensions of the The set may not allow the entire circumference or radial face to be seen by the assemblies at any given moment. The prior art most closely related to the present invention is described in U.S. Patent No. 4,406,939 (Golker) entitled "Method for the Manufacture of a Code Disk for Optical Incremental Shaft Encoders and Absolute Shaft Encoders" code for optical arrow encoders by increments and absolute arrow encoders) showing the use of laser techniques for the manufacture of arrow encoder patterns. The essence of the present method lies in the application of radiation, and particularly optical laser radiation, pattern forming techniques simultaneously on the two mutually adjacent grid elements of an arrow assembly. The arrow assembly is assembled prior to irradiation, and comprises the two fixed or integrated grid elements with two torque input members connected through a torsional deformation connection. The simultaneous irradiation of the two grid elements of the arrow assembly offers a very precise control of the relative positioning of the two grid patterns generated in this way for the condition of zero torque alignment. In addition, since the torque patterns are mutually adjacent, a single radiation source can be employed for both patterns with further improvement of pattern placement. This contrasts with the use of optical pattern-forming methods in accordance with what has been disclosed in the aforementioned prior art which, if employed, requires "pattern pre-formation" independent of the two grid elements (known as "discs"). of codes ") before the assembly of the arrow, with the subsequent introduction of inaccuracies in the relative positioning of the two grid patterns during the subsequent assembly operation.

The radiation in the present specification includes optical electromagnetic radiation with wavelengths in vacuum between 40 nm and 1 mm, in accordance with the definition of The International Society for Optical Engineering.

The advantages of a method according to the present invention for constructing a torque transducer of "reflecting grids" (in accordance with that presented in Co-pending Patent Application No. PCT / AU98 / 00645) or a transducer of "Transmissive Grid Torque" (in accordance with that presented in the copending Australian Provisional Patent Application No. PP0984 filed December 17, 1997 entitled "Transmission Path Torque Transducer") (Transition Torque Transducer transmission)) are detached from the generation of the patterns after the assembly of the arrow. This means that the relative locations of the two patterns are determined with great precision that is not affected by subsequent assembly operations as would be the case if the patterns were generated before the arrow assembly. First, the calibration of the finished transducer is not required, saving cost and manufacturing time. Second, the arrows can be interchanged without recalibration and precise assembly methods, and the assemblies can also be interchanged without recalibration and precise assembly methods. Third, the transducer can be disassembled and reassembled if required for maintenance or repair without the need for special tools or precise assembly methods. Fourth, the "locked" nature of the relative pattern settings means that adjustment features such as screws and detents are not required, which consequently eliminates the possibility that the transducer may be accidentally miscalculated by the user or of repair personnel with insufficient training. Fifth, the use of irradiation allows the generation of patterns in the grid elements with great precision and speed. Finally, the use of irradiation allows the flexible generation of complex and angularly non-repetitive patterns, such as, for example, bar codes, for example by manipulating a laser. This allows the torque transducer shaft to have a simpler construction since "intermediation" problems can be eliminated since the individual marks (or groups of regions of high and low reflectivity or transmissibility) have a unique coded identity . Intermediation is defined in this application as the situation in which sufficient angular deviation occurs between two grid elements such that the placement of the respective patterns is identical to their placement for a smaller amount of angular deviation, thus providing an indetermination and a potentially false measurement of the torque on the arrow. The bar codes provide an absolute indication as to which brand is being viewed through the set thus eliminating the lack of determination caused by the intermediation. Markings in the form of bar code patterns also allow a simple determination of the absolute angular position of the arrow, providing additional transducer functionality or eliminating the need for external angle encoders. SUMMARY OF THE INVENTION The present invention is a method for the manufacture of grid patterns on the surfaces of grid elements of a torque transducer, the torque transducer comprises an arrow with a longitudinal axis, the arrow comprises a first substantially rigid torque input member and a second substantially rigid torque input member connected by a connection allowing torsional deformation, the connection allows the angular deviation of the first torque input member relative to the second torque input member as a function of the magnitude of the torque on the shaft, a first grid element fixed or integrated with the first torque input member and a second grid element fixed or integrated with the second torque input member, the surfaces of the two grid elements are adjacent and can be relatively displaced as a function of the torque in the arrow, the method comprises the steps of: a first step of forming an assembly by means of the axial and rotational fixing of the first torque input member and second torque input member and respective grid elements to the connection that allows torsional deformation; a second assembling step of the assembly in a machine comprising a radiation source positioned to irradiate regions of the adjacent surfaces of the two grid elements while maintaining a predetermined relative angular displacement between the two torque input members with respect to to its condition of zero torque alignment; and a third step for simultaneously radiating regions of the adjacent surfaces of the two grid elements while maintaining the predetermined angular displacement between the two torque input members; thus generating grid patterns on the surfaces of the two grid elements of the assembly that present a precise mutual alignment for this condition of zero torque alignment. In a first embodiment it is preferred that the machine offers a mounting for the rotation of the assembly around the longitudinal axis of the arrow and the third step further comprises the rotation of the assembly and the successive irradiation of regions of the adjacent surfaces at predetermined angular rotation positions. of the assembly. It is preferred that the assembly rotate substantially one revolution during successive rotations. It is preferred that the assembly be rotationally stationary during at least one of the successive irradiations. Alternatively, it is preferred that the assembly rotate during at least one of the successive irradiations. In a second embodiment it is preferred that the assembly be mounted stationary in the machine during the third step. It is preferred that the surface of the at least the first grid element or the second grid element be substantially cylindrical, with its central axis collinear with the longitudinal axis of the arrow. Alternatively, it is preferred that the surface of at least one of the first grid element or the second grid element be substantially flat and positioned radially relative to the longitudinal axis of the arrow.

Alternatively, it is preferred that the surface of at least one of the first grid element or second grid element be substantially conical, with its central axis collinear with the longitudinal axis of the arrow. Alternatively, it is preferred that the surface of at least one of the first grid element or second grid element be substantially axisymmetric, with its central axis collinear with the longitudinal axis of the arrow. It is preferred that each grid pattern comprises alternating regions of high and low reflectivity or transmissibility for a given incident electromagnetic radiation. It is preferred that a radiation-opaque mask is placed between the radiation source and the surfaces of the grid elements and the geometry of the mask determines the shape and placement of the patterns. Alternatively, the radiation source comprises a laser that radiates the surfaces of the grid elements and the shape and placement of the patterns are determined by the focus control and / or contact position of the laser beam on the grid elements. Alternatively, the radiation source comprises a laser that radiates the surfaces of the grid elements and the shape and placement of the patterns are determined by controlling the relative positions of the grid elements and the laser.

It is preferred that the predetermined relative angular displacement maintained between the two torque input members be substantially zero. It is preferred that the grid pattern in at least one of the grid elements be arranged in the form of a bar code or a succession of bar codes. It is preferred that the irradiation removes the material or changes the physical or chemical properties of the regions of adjacent surfaces of the grid elements, thereby increasing or decreasing the reflectivity or transmissibility of these regions. Alternatively, a polymer layer such as polyimide is applied to the adjacent surfaces of the grid elements prior to irradiation, and the irradiation removes this layer from the regions of the grid elements, thus exposing the original surface of the elements of the grid elements. grid, the reflectivity or transmissibility being increased or decreased in comparison with the surface of the polymer layer. Alternatively, a layer of inorganic material such as alumina ceramic is applied to the adjacent surfaces of the grid elements prior to irradiation, and the irradiation removes this layer from the regions of the grid elements, thus exposing the original surface of the grid elements. the grid elements, the reflectivity or transmissibility being increased or decreased in comparison with the surface of the inorganic layer. Alternatively, a layer of metallic material such as electrodeposited copper is applied on the adjacent surfaces of the grid elements prior to irradiation, and the irradiation removes this layer from the regions of the grid elements, thus exposing the original surface of the elements. grid elements, in this way the reflectivity or transmissibility is increased or decreased compared to the surface of the metal layer. Alternatively, the surfaces comprise a proportion of titanium dioxide and the change in chemical properties is effected by the exchange of titanium dioxide to titanium oxide. Alternatively, the surfaces comprise a proportion of aluminum oxide, and the change in chemical properties is effected by a reduction in the ratio between aluminum oxide and aluminum. Alternatively, the irradiation cures regions of an uncured polymer layer applied on the adjacent surfaces of the grid elements prior to irradiation, the surfaces of these regions exhibit an increase or decrease in reflectivity or transmissibility compared to the original surface of the grid elements that are subsequently exposed by removing the remaining uncured polymer after irradiation. It is preferred that the assembly be subjected to turning, grinding, roller burnishing, fine grinding or other processes in order to improve the relative cylindrical character or the concentricity of the surface of the at least one substantially cylindrical grid element or, alternatively, to improve the relative flatness of the the surface of the at least one substantially flat and radially positioned grid element or, alternatively, to improve the relative conical character or the concentricity of the surface of the at least one substantially conical grid element, prior to generation of the grid pattern. BRIEF DESCRIPTION OF THE DRAWINGS The present method will be described below by means of a non-limiting example with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a "reflective grid" torque transducer "manufactured by a method according to a first embodiment of the present invention, showing the arrow assembly comprising two torque input members connected by a torsion bar, two grid elements with grid patterns and associated assemblies and source of EMR, Figure 2 is an isometric view of the arrow assembly illustrated in Figure 1, rotated about its axis with a radiation source that generates grid patterns in the grid elements (with the predetermined relative angular displacement between the two torque input members not being null) in accordance with a first embodiment of the present invention, the figures 3a-c show alternative methods for irradiating the surfaces of the grid elements, Fig. 4 is an isometric view of the arrow assembly illustrated in Fig. 1, rotated about its axis with a radiation source that generates grid patterns in the grid elements (with the predetermined relative angular displacement between the two torque input members being substantially zero) in accordance with a first embodiment of the present invention, Fig. 5 is a cross-sectional view of a torque transducer of torsion of "reflecting grid", where the grid elements are flat and placed radially relative to the arrow axis, Figure 6 is an isometric view of the arrow assembly illustrated in Figure 5, rotated about its axis with a source of radiation that generates grid patterns in the grid elements according to a first embodiment of the present invention, figure 7 is a vi The isometric assembly of the arrow assembly according to FIG. 5, with the stationary arrow assembly and a radiation source generating grid patterns by crossing a focused irradiation along a predetermined path according to a second embodiment of the present invention. Fig. 8 is a more detailed cross section of the arrow assembly illustrated in Fig. 7, showing the path traversed by the irradiation, Fig. 9 shows a cross section of one of the grid elements in the cut AA in the Figure 1, which illustrates the situation in which the grid patterns are generated while the arrow is rotating, Figure 10 is a diagrammatic view of a part of the surfaces of the grid elements illustrated in Figure 1, where the grid patterns are alternatively in the form of a succession of subordinate standards of bar codes, Figure 11 shows a cross section of one of the elements of grid in the cross section AA in figure 1, where the grid patterns are generated by the removal of material or by a change of the chemical or physical properties of the grid elements, figure 12 shows a cross section of one of the grid elements in the cross section AA in figure 1, where the grid patterns are generated by applying additional material to the grid element with a subsequent irradiation that removes the predetermined regions, Figure 13 shows a cross section of one of the grid elements in section AA in Figure 1, where the grid patterns are generated by applying additional material to the grid element with irradiation that cures predetermined regions, by the subsequent removal of uncured material. MODE OF THE INVENTION Figure 1 is a cross section of a "reflective grid" torque transducer manufactured by a method according to a first embodiment of the present invention showing an arrow assembly comprising grid elements 4 5 cylindrical fixed or integrated with torque input members 1 2. The torque input members 1 2 are fixed in a rotational axial manner at the ends of a connection that allows torsional deformation in the form of torsion bar 3, through transverse pins 61 62. The grid elements 4 5 comprise cylindrical peripheral surfaces composed of alternating regions of high low reflectivity, provided by grid patterns 11 12, respectively. This assembly is enclosed in a frame 6 supported by bearings 7 8. One or several sources of electromagnetic radiation (EMR) 13 are placed to illuminate the surfaces in the vicinity of the assembly 9. The assembly 9, comprising one or more Sensors sensitive to electromagnetic radiation receives the incident electromagnetic radiation from the surface the images generated in this way in the set 9 are processed by a processor 10. The methods by which the images are processed are well known in the analysis technique of images, some of these methods used are described in "VISION CHIPS": Implementing Vision Algorithms with Analog VLSI Circuits ", by Christof Koch Hua Li, IEEE Computer Society Press, ISBN 0-8186-6492-4. can be constructed from two sets of linear photodetectors such as the TSL1410 device manufactured by Texas Instruments Inc. Figures 2 3 show a method for manufacturing the arrow assembly of the torque transducer illustrated in Figure 1 in accordance with a first embodiment of the present invention. Figure 2 is an isometric view of the arrow assembly, showing cylindrical grid elements 4 5 fixed or integrated with the torque input members 1 2, in turn fixed in a rotational axial manner at the ends of the torsion bar 3. The arrow assembly is gripped at both ends by collars 16 17 of transmission assemblies 50 51, respectively. Each of the transmission assemblies 50 51 comprises a hollow frame servo motor an angle encoder connected to the controller 52, are supported to rotate on the shaft 49 in the frame of a machine structure (not shown). The controller 52 receives angular position inputs from the encoders of each of the transmission assemblies 50 51 generates appropriate control signals for the respective servomotors, thereby achieving a predetermined sequence of rotational movement for the arrow assembly . Sufficient torque is applied by the transmission assemblies 50 51 in order to maintain, through a closed loop control, a fixed, predetermined relative angular displacement of the torque input members 1 2 ( consequently in this way also of the grid elements 4 5) that is maintained throughout the pattern forming process. The radiation source 18 offers a diffuse irradiation 19 to the cylindrical peripheral surfaces of the grid elements 4 5 through a mask 53 comprising the openings 54 55. A radiation source 18 is also controlled through a controller 52. The location of transmission assemblies 50 51, radiation source 18 and mask 53 is accurately determined relative to the arrow assembly through the machine structure (not shown). The transmission assemblies 50 and 51 are arranged to rotate the arrow assembly about the arrow assembly shaft 49 with a predetermined sequence of angular movement, whereby the arrow assembly is stationary at a predetermined angular position during the application of the irradiation 19 in accordance with that indicated by the controller 52, and then rotates in the direction B with a predetermined angular velocity and an acceleration profile towards the next predetermined angular position and stops before the next irradiation application 19. The irradiation therefore generates grid patterns 11 and 12 comprising alternate regions of high and low reflectivity for the given EMR source (13 in Figure 1) on the surfaces of the grid elements 4 and 5 that comprise sequentially generated individual subordinate standards. , b, c, d, e and 12a, b, c, d, e .... respectively (see figure 3a). At the terminal the pattern forming process, the transmission assemblies 50 and 51 cease to apply a torque to the arrow assembly, thus allowing the torsion bar 3 to relax and restore the relative angular displacement of the input members of the torsion bar. torque 1 and 2 (and therefore also grid elements 4 and 5) to zero. The final non-deviated relative positioning of the grid patterns can, for example, as shown by dots for the grid element 5, with a grid pattern 11 interposed between the grid pattern 12. Figures 3b and 3c show some arrangements of generating alternative grid patterns that can be applied to the manufacturing method in accordance with the first embodiment of the present invention. Figure 3b shows a diffuse irradiation 19 directed by a single opening 56 in a mask 53 that creates grid patterns 11 and 12 in grid elements 4 and 5 that extend to their mutual interface. Figure 3c shows a radiation source 18 which provides a narrow beam irradiation 19 to the grid elements 4 and 5 without using a mask. The irradiation is "guided" by the use of deflecting mirrors, controlled by signals from the controller 52. Such an arrangement can be used to produce grid patterns according to what is illustrated in FIG. 3 a with a suitable activated-deactivated modulation of the irradiation 19 in coordination with the deviation of the mirrors. Figure 4 shows an alternative method of manufacturing the torque converter transducer arrow assembly according to the first embodiment of the present invention, being an isometric view of the arrow assembly, showing the cylindrical grid elements 4 and 5 fixed or integrated with the torque input members 1 and 2, in turn fixed in a rotational and axial manner at the ends of the torsion bar 3. One end of the arrow assembly is gripped by a collar 17 of the assembly transmission 51, comprising a servo hollow frame motor and an angle encoder connected to controller 52, and the other end is supported on motor shaft 60. Both transmission assembly 51 and motor shaft 60 are supported by the frame a machine structure (not illustrated). The controller 52 receives an angular position input from the encoder of the transmission assembly 51 and generates the appropriate control signal for the servo motor to achieve a predetermined sequence of rotational movement for the arrow assembly. The radiation source 18 offers a diffuse irradiation 19 to the cylindrical surfaces of the grid elements 4 and 5 through a mask 53 comprising openings 54 and 55. The radiation source 18 is also controlled by the controller 52. The location of the transmission assembly 51, motor shaft 60, radiation source 18 and mask 53 are determined precisely in relation to the arrow assembly through the machine structure (not shown). The transmission assembly 5 is arranged to rotate the arrow assembly about an arrow assembly shaft 60 with a predetermined sequence of angular movement, whereby the arrow assembly is stationary at a predetermined angular position during the irradiation application. 19 as indicated by the controller 52, then rotates in the direction B with a predetermined angular velocity and a predetermined acceleration profile up to the next predetermined angular position and stops before the next irradiation application 19. The irradiation consequently generates patterns grid 11 and 12 comprising alternate regions of high and low reflectivity for the given EMR source (13 in Figure 1), on the surfaces of the grid elements 4 and 5 comprising sequentially generated individual subordinate standards lla, b, c, d, e and 12a, b, c, d, e, respectively (see figure 3a). The central axis 60 has a sufficiently low rotation friction such that the relative angular displacement of the grid patterns 11 and 12 from the non-deviated state (i.e., zero torque) during the pattern formation process is substantially zero, and therefore does not adversely affect the operation of the torque transducer. Figure 5 is a cross section of an alternative "reflective grid" torque transducer fabricated by a method of compliance with either the first embodiment or a second embodiment of the present invention. The grid elements 4 and 5 are fixed or integrated with the torque input members 1 and 2, respectively, which in turn are rotationally and axially fixed at the ends of a torsion bar 3 through transverse pins 61 and 62. The grid elements 4 and 5 comprise flat and radially placed surfaces composed of alternating regions of high and low reflectivity, provided by grid patterns 11 and 12. This assembly is enclosed in a frame 6 and supported by bearings. 7 and 8. One or several sources of electromagnetic radiation (EMR) 13 are placed to illuminate the surfaces in the vicinity of the assembly 9. The assembly 9, comprising one or more detectors sensitive to electromagnetic radiation receives the electromagnetic radiation incident from the surfaces and the images generated in this way in the assembly 9 are processed through the processor 10. Figure 6 shows a method for manufacturing the arrow assembly of the torque transducer illustrated in Figure 5 in accordance with the first embodiment of the present invention, and is analogous to the method described with reference to Figures 2, 3 and 4. However, in this case, the alignment axes of the radiation source 18, irradiation 19 and mask 53 are rearranged to allow the grid patterns 11 and 12 to be applied to the flat surfaces of the grid elements 4 and 5 perpendicular to the arrow shaft. Figures 7 and 8 show a method for manufacturing the arrow assembly of the torque transducer illustrated in Figure 5 in accordance with the second embodiment of the present invention, and they are isometric views of the arrow assembly, showing elements 4 and 5 grid grids arranged radially fixed or integrated with the torque input members 1 and 2, in turn fixed in a rotational and axial manner at the ends of a torsion bar 3. The arrow assembly is gripped by a collar 51 rigidly fixed on the frame 51 of a machine structure (not shown), consequently the arrow assembly can not rotate about the arrow shaft 49. A radiation source 18 is also fixed on the structure of the machine and consequently the location of the collar 51 and of the radiation source 18 are determined with precision in relation to the arrow assembly by the structure of the machine. na (not illustrated).

The irradiation source 18 offers an irradiation 19 focused towards the flat surfaces of the grid elements 4 and 5, thus generating grid patterns 11 and 12 comprising alternating regions of high and low reflectivity for the given EMR source (13 in the figure 5). In this second embodiment of the present invention, the regions of high reflectivity are generated sequentially, where each successive region of high reflectivity 91a, 91b, 91c, etc., is generated by crossing a focused irradiation 19 directed towards the grid elements. 4 and 5 through the arc C. At the end of the transverse arc C, the radiation source 18 is redirected to the next region, by the movement of the irradiation in the direction E by an incremental arc D. Figure 7 shows a case in which the transverse region 91b has been terminated and the irradiation has been displaced by incremental arc D from region 91b to region 91c. Transverse region 91c extends from position 91c? to position 91c2 and it is shown partially completed. The shaded areas of regions 91c, 91d, etc., represent regions still pending irradiation in subsequent passes. The controller 52 offers appropriate control signals to the radiation source 18 to effect passes through 91a, 91b, 91c, 91d, etc. A suitable system that includes a controller and deflectable mirrors is "SH Series Marking Heads" manufactured by Synrad of WA, United States of America. In the illustrated example, the regions 91a, 91b, 91c, 91d, etc. are generated by a single irradiation pass 19 through an arc C. However, it is apparent that the same method can also be applied in the case of which requires multiple passes for each successive region, for example, when the predicted width of the region is greater than the width of the focused irradiation, or when the chemical or physical changes needed to produce the region require greater energy than what the radiation source 18 can provide during a single pass. It is also apparent that the same method can also be applied by the movement of the radiation source 18 relative to the grid elements 4 and 5, instead of the mode illustrated in FIGS. 7 and 8 where the irradiation 19 passes through the defined arcs C and D with the position of the radiation source 18 being fixed relative to the position of the grid elements 4 and 5. Figure 9 shows the generations of grid patterns according to the first embodiment of the present invention without stop the arrow assembly for successive irradiation. This is a cross-sectional view AA of the cylindrical grid element 4 in Fig. 1, showing the generation of the grid pattern 11 by irradiation 19 provided by a radiation source 18. This irradiation 19 occurs "during travel" while that the grid element is rotating in the "B" direction as shown. Since irradiation 19 requires a finite time "t" to generate the predetermined subordinate pattern, the grid element is displaced by the distance "e" during the period of time in which the irradiation occurs, which means that the areas "x" and "y" are irradiated for a shorter period of time than the rest of the subordinate pattern and the edges of the subordinate pattern are therefore less distinct. This displacement "e" can be sufficiently small by the correct selection of the angular velocity of the arrow assembly and by the correct selection of the irradiation time "t" in such a way that the grid pattern 11 provides an adequate precision for a correct operation of the torque transducer. Fig. 10 is a diagrammatic view of a portion of the surfaces of the grid elements 4 and 5 illustrated in Fig. 1, where the grid patterns are alternately in the form of a succession of subordinate bar code patterns. The construction of the transducer, including the arrow assembly, is essentially the same as the construction illustrated in Figure 1. Grid elements 4 and 5 comprise grid patterns 11 and 12 at their cylindrical peripheries, respectively, where the grid slave standards Individuals consist of bar code sequences of regions of high reflectivity 24 (illustrated in black in the figure) and of low reflectivity 25 (illustrated in white in the figure). One or more sources of electromagnetic radiation (EMR) 13 are placed to illuminate the surfaces in the vicinity of the arrangement 9. The arrangement 9, comprising one or more detectors sensitive to electromagnetic radiation, receives the incident electromagnetic radiation from the surfaces and the electromagnetic radiation. images generated in this way in set 9 are processed by the processor 10. The individual bar code sub-patterns are appropriately coded and arranged by default around the cylindrical periphery of the grid elements in such a way that the processor 10 can determining the relative angular displacement of the grid patterns 11 and 12, and the absolute angular position of the grid patterns 11 and 12 relative to the assembly 9. Figure 11 is a section of the surface of the grid element 4 in the section AA in Figure 1 showing the physical effect of irradiation 19 on the surface of the grid element during generation of the grid pattern 11. The irradiation 19 occurs repeatedly while the grid element is rotating in the "B" direction as shown, and results in the removal of material or changes the surface finish, the physical or chemical properties of regions of the grid element 4, which increases or decreases the reflectivity of these regions, thus generating a grid pattern 11. For example, a grid pattern 11 may consist of aluminum regions generated by irradiation 19 of an anodized aluminum surface of grid element, where the irradiation chemically reduces the anodized aluminum oxide material. Figure 12 is a section of the surface of the grid element 4 in section AA in Figure 1, showing an alternative method to the method described in Figure 11 to generate regions of high and low reflectivity. A polymer layer 26 was previously applied on the surface of the grid element 4. Irradiation 19 occurs repeatedly while the grid element rotates in the "B" direction as illustrated, and removes regions of layer 26 which results in the exposure of regions 27 of the original surface of the grid element 4. These regions 27 exhibit a greater or lesser reflectivity compared to the surface of layer 26, thus generating a grid pattern 11. An example of a suitable polymer 26 is " Eagle Resist "manufactured by Shipley Co. Figure 13 is a section of the surface of the grid element 4 in section AA in Figure 1, showing another alternative method to the method described in Figure 11 to generate high and low regions. reflectivity An uncured polymer layer 28 was previously applied on the surface of the grid element 4. The irradiation 19 occurs repeatedly while the grid element rotates in a "B" direction as shown, resulting in the curing of the regions 30 of the layer 28. The subsequent removal of the remaining uncured polymer 31 results in the exposure of the regions 29 of the original surface of the grid element 4. These regions exhibit a greater or lesser reflectivity compared to layer 28, thus generating a grid pattern 11. An example of a suitable polymer is "Flexmate" manufactured by DecoChem of Mishawaka, IN, United States of America. The first embodiment and the second embodiment of the present invention are described herein in relation to a method for manufacturing a "reflective grid" torque transducer. Nevertheless, it is apparent that the same method can also be applied to the manufacture of a "transmissive grid" torque transducer. Said torque transducer similarly employs flat grid elements positioned substantially cylindrically or radially. However, the part of the respective grid element in which the grid pattern is applied is arranged to be substantially transparent to the electromagnetic radiation emitted by the source (s). The source (s) and the set (s) are arranged in such a way that the electromagnetic radiations emitted by the set (s) pass through this transparent medium and are interrupted by the pattern of grid applied to the surface of the respective grid element or close to said surface. The regions of high and low transmissibility in this pattern generate an image in the respective set that receives the incident electromagnetic radiation. The method, according to the present invention, for the manufacture of a grid pattern for said "transmissive grid" torque transducer is identical to the method described in this specification with reference to a grid pattern for a torque transducer. of "reflective grid" torsion, the only difference is that in the previous case the medium in which the grid pattern is applied is necessarily substantially transparent to the electromagnetic radiation emitted by the source (it is typically made of glass or of a transparent plastic material). Those skilled in the art will note that numerous variations and / or modifications can be made in relation to the present invention illustrated in the specific embodiments without departing from the spirit or scope of the present invention described in general terms. The modalities presented should therefore be considered, in all aspects, as illustrative of the present invention, without limiting implications.

Claims (25)

1. CLAIMS A method for manufacturing grid patterns on the surfaces of grid elements of a torque transducer, the torque transducer comprises an arrow with a longitudinal axis, the arrow comprises a first torque input member substantially rigid and a second input member of substantially rigid torque connected by a connection allowing torsional deformation, the connection thus allows an angular deviation of the first torque input member relative to the second input member of torque as a function of the magnitude of the torque on the arrow, a first grid element fixed or integrated with the first torque input member and a second grid element fixed or integrated with the second grid member; torque input, the surfaces of the two grid elements are adjacent and can move relatively As a function of a torque in the arrow, the method comprises the steps of: a first step of forming an assembly by means of the rotational and axial fixing of the first torque input member and the second torque input member of twisting and the respective grid elements on the connection that can be twisted by twisting; a second assembling step of the assembly in a machine comprising a radiation source positioned for the purpose of irradiating regions of the adjacent surfaces of the two grid elements while maintaining a predetermined relative angular displacement between the two torque input members of torsion in relation to its condition of zero torque alignment; and a third step for simultaneously radiating regions of the adjacent surfaces of the two grid elements while maintaining the predetermined angular displacement between the two torque input members; thus generating grid patterns on the surfaces of the two grid elements of the assembly that are mutually precisely aligned for this condition of zero torque alignment.
2. A method according to claim 1, wherein the machine provides the assembly for the rotation of the assembly around the longitudinal axis of the arrow and the third step further comprises the rotation of the assembly and the successive irradiation of the regions of the adjacent surfaces in positions of predetermined angular rotation of the assembly.
3. A method according to claim 2, wherein the assembly rotates substantially by one revolution during successive rotations.
4. A method according to claim 2, wherein the assembly rotates in a stationary manner during at least one of the successive irradiations.
5. A method according to claim 2, wherein the assembly rotates during at least one of the successive irradiations.
6. A method according to claim 1, wherein the assembly is stationary mounted in the machine during the third step.
7. A method according to claim 1, wherein the surface of at least one of the first grid element or second grid element is substantially cylindrical, with its central axis collinear with the longitudinal axis of the arrow.
8. A method according to claim 1, wherein the surface of at least one of the first grid element or second grid element is substantially flat and positioned radially relative to the longitudinal axis of the arrow.
9. A method according to claim 1, wherein the surface of at least one of the first grid element and second grid element is substantially conical, with its central axis collinear with the longitudinal axis of the arrow.
10. 10. A method according to claim 1, wherein the surface of at least one of the first grid element and second grid element is substantially axisymmetric, with its colinear central axis with the longitudinal axis of the arrow.
11. 11. A method according to claim 1, wherein each grid pattern comprises alternating regions of high and low reflectivity transmissibility for a given incident electromagnetic radiation.
12. 12. A method according to claim 1, wherein a radiation-opaque mask is interposed between the radiation source and the surfaces of the grid elements and the geometry of the mask determines the shape and placement of the patterns.
13. 13. A method according to claim 1, wherein the radiation source comprises a laser that radiates the surfaces of the grid elements and the shape and placement of the patterns are determined by means of the control of the focus of the laser beam and / or contact position in the grid elements.
14. A method according to claim 1, wherein the radiation source comprises a laser that radiates the surfaces of the grid elements and the shape and placement of the patterns are determined by controlling the relative positions of the grid elements and the laser.
15. 15. A method according to claim 1, wherein the predetermined relative angular displacement maintained between the two torque input members is substantially zero ..}.
16. 16. A method according to claim 1, wherein the grid pattern in at least one of the grid elements is arranged in the form of a bar code or a succession of bar codes.
17. A method according to claim 11, wherein the irradiation removes the material or changes the physical or chemical properties of regions of the adjacent surfaces of the grid elements, thereby increasing or decreasing the reflectivity or transmissibility of these regions.
18. 18. A method according to claim 11, wherein a polymer layer such as for example polyimide is applied on the adjacent surfaces of the grid elements prior to irradiation, and the irradiation removes this layer of regions from the grid elements, thus exposing the original surface of the grid elements, thereby increasing or decreasing the reflectivity or transmissibility compared to the surface of the polymer layer.
19. 19. A method according to claim 11, wherein a layer of inorganic material such as alumina ceramic is applied to the adjacent surfaces of the grid elements prior to irradiation, and the irradiation removes this layer from regions of the elements. of grid, thus exposing the original surface of the grid elements, thereby increasing or decreasing the reflectivity or transmissibility compared to the surface of the inorganic layer. .
20. A method according to claim 11, wherein a layer of metallic material such as electrodeposited copper is applied on the adjacent surfaces of grid elements prior to irradiation, and the irradiation removes this layer of regions from the grid elements, exposing thus the original surface of the grid elements, thereby increasing or decreasing the reflectivity or transmissibility compared to the surface of the metal layer. .
21. A method according to claim 17, wherein the surfaces comprise a proportion of titanium dioxide and the change of chemical properties is effected by the exchange of titanium dioxide in titanium oxide. .
22. A method according to claim 17, wherein the surfaces comprise a proportion of aluminum oxide, and the change in chemical properties is effected by the reduction of the aluminum oxide in aluminum.
23. 23. A method according to claim 11, wherein the irradiation cures regions of an uncured polymer layer applied on the adjacent surfaces of the grid elements prior to irradiation., the surfaces of these regions exhibit an increased or decreased reflectivity or transmissibility compared to the original surface of the grid elements that are subsequently exposed by removing the remaining uncured polymer after irradiation.
24. 24. A method according to claim 7, wherein the assembly is subjected to turning, grinding, roller burnishing, fine grinding or other processes in order to improve the relative concentric or cylindrical character of the surface of the at least one element substantially cylindrical grid before the generation of a grid pattern.
25. 25. A method according to claim 8, wherein the assembly is subjected to turning, grinding, roller burnishing, fine grinding or other processes in order to improve the relative plane character of the surface of the at least one grid element substantially flat and placed radially before generation of the grid pattern. . A method according to claim 9, wherein the assembly is subjected to turning, grinding, roller burnishing, fine grinding or other processes to improve the conical or concentric relative character of the surface of the at least one substantially conical grid element prior to generate the grid pattern. SUMMARY OF THE INVENTION A method for manufacturing patterns on grid element surfaces of a torque transducer having an arrow comprising a first rigid torque input member and a second input member of rigid torque connected by a torsional deformation connection allowing a relative angular deviation between the first input member and the second input member, a first grid element and a second grid element respectively associated with the first input member and the second inlet member, the surfaces of the grid elements are adjacent to each other and can be relatively displaced as a function of torque in the arrow, the method comprising the steps of: forming an assembly by fastening in a rotatable manner and axial of the input members and respective grid elements to the torsion connection; mounting the assembly in a machine comprising a radiation source positioned to radiate regions of the surfaces of the grid elements while maintaining a relative angular displacement between the torque input members relative to their torque alignment condition of zero torsion; and simultaneously radiating regions of the surfaces of the grid elements while maintaining the angular displacement between the input torque members.