FR2858371A1 - IMPROVED DEVICE FOR SETTING RECTIFIERS OF A TURBOJET COMPRESSOR - Google Patents

Abstract

A device is dedicated to the setting of one or more pivoting flow rectifiers (R) comprising drive means (4-6) intended to drive their axis of rotation (3) in rotation in order to set them angularly as a function of data of angular positions delivered by control means. These control means comprise, on the one hand, illumination means (8,10) responsible for delivering a light at the level of an illumination zone (11), on the second hand, an encoder element ( 12) secured to the axis (3) of the rectifier (R) in the illumination zone (11) and arranged so as to interact with the illumination light to generate optical signals representative of the angular position of the rectifier, d 'a third part, means (13a) responsible for collecting the optical signals, and a fourth part, processing means (7) responsible for determining angular position data from the collected optical signals.

Description

Improved rectifier setting device for a compressor of

turbojet

  The invention relates to the field of turbojet compressors, and more particularly that of the calibration of the pivotal flow rectifiers of these compressors.

  As known to those skilled in the art, in an axial turbojet engine, the gases are compressed before combustion by a compressor comprising several stages. Each stage is composed of a rotating rotor wheel for accelerating the axial flow and a fixed blade crown for producing the pressure rise. In order to optimize and adapt the operation of the compressor, it is provided for the fixed vanes (rectifiers) a limited orientation ability or "setting" of the aerodynamic profile whose management is provided by the engine control. The rectifiers are usually wedged by means of a wedging device comprising a drive mechanism coupled to their axes of rotation (also called "blade tail axes"). More specifically, the wedging device comprises control means for determining the angular positioning of one of the rectifiers and for supplying the drive mechanism with instructions, consisting of angular position data, so that it places the concerned rectifiers in selected angular positions.

  So that the guidance is optimal, it is essential that the determination of the angular positioning is accurate. However, because of the presence of high temperatures near the rectifier, the angular positioning measurement is carried out remotely, preferably near the control cylinder. This measurement is therefore disturbed by the existence of strong vibrations, thermal expansion and mechanical linkages.

  The invention therefore aims to remedy all or part of the aforementioned drawbacks.

  To this end, it proposes a device dedicated to the wedging of one or more pivoting flow rectifiers comprising drive means intended to rotate their axes of rotation in order to angularly wedge them according to position data delivered by means of control.

  This device is characterized in that its control means comprise, firstly, illumination means responsible for delivering light at an illumination zone, secondly an encoder element. secured to the axis of the rectifier in the illumination zone and arranged to interact with the illumination light to generate optical signals representative of the angular position of the rectifier, thirdly, means responsible for collecting the 10 optical signals, and fourthly, processing means for determining angular position data from the collected optical signals.

  Thanks to the use of optical detection means, the angular positioning is measured directly on the axis of the rectifier. As the measurement is no longer distorted by a kinematic clearance, thermal expansion and vibrations, its accuracy is therefore significantly improved.

  Preferably, the encoder element is in the form of a (portion of) encoder wheel equipped with at least one configured range in order to allow the generation of variable optical signals as a function of its position within the region of illumination.

  Furthermore, the illumination means preferably comprise at least one optical fiber provided with a shaped end (possibly combined with optical shaping means), so as to illuminate the illumination area on a surface 25 of dimensions selected.

  The invention can be divided into two classes of embodiments depending on whether the optical signals are obtained by transmission or by reflection.

  The first class (concerning the transmission) has at least two branches.

  A first branch relates to the encoder elements comprising a range provided with at least one slot shaped so as to transmit the light differently according to the angular position of the encoder element. For example, it is expected that a progressive opening slot or a plurality of slots of different shapes and / or spaced from each other with a variable pitch.

  A second branch relates to encoder elements comprising a transparent range comprising at least one zone provided with markings. In this case, it is possible for example to provide a transparent scanning reticle interposed between the illumination light and the encoder element, and collection means comprising photodetectors implanted opposite the beach, on the opposite side to the zone of illumination and responsible for delivering electrical signals representative of the optical signals resulting from the interaction between the illuminating light, the scanning reticle and the markings.

  As a variant, in these two branches, the collection means may comprise photodetectors implanted opposite the range, on the side opposite the illumination zone 15 and responsible for delivering electrical signals, representative of the optical signals transmitted at the level of the beach. In another variant, the collection means may comprise one or more optical fibers provided with a shaped end (possibly combined with optical shaping means), so as to collect the optical signals transmitted at the level of the range. In the second class, the range of the encoder element comprises at least one reflecting element shaped to reflect the light differently according to the angular position of the encoder element.

  In this case, it is possible, for example, to provide, firstly, a transparent scanning reticle interposed between the illumination light and the encoder element and defining a transparent phase grating, and a second part, a reflecting element. with markings, and thirdly, collection means comprising photodetectors implanted upstream of the scanning reticle and charged to deliver electrical signals representative of the optical signals resulting from the interaction between the illumination light, the reticle scan and markings.

  Alternatively, the collection means may comprise at least one optical fiber having a shaped end so as to collect the optical signals reflected at the level of the range.

  According to another characteristic of the invention, at least part of the coder element, part of the illumination means and at least part of the collection means 5 are housed in a light-tight enclosure, so that the measurements are not disturbed by stray light.

  Furthermore, the processing means are preferably housed in a remote housing of the rectifier, so as not to be exposed to high temperatures. Other features and advantages of the invention will appear on examining the following detailed description, and the accompanying drawings, in which: FIG. 1 is a schematic cross-sectional view of a compressor; FIG. 2 schematically illustrates, in a side view, an exemplary embodiment of a wedging device according to the invention; FIG. 3 is a view from above schematically illustrating the embodiment of a turbojet; FIG. implantation of the coding wheel of the chocking device of FIG. 2; - FIG. 4 schematically illustrates a first exemplary embodiment of the detection means 20 of the chocking device, in a cross-sectional view along the axis IVIV of FIG. FIG. 5 diagrammatically illustrates a second exemplary embodiment of the detection means of the wedging device, in a cross-sectional view, FIG. 6 schematically illustrates a third embodiment of FIG. FIG. 7 is a view from above schematically illustrating an encoder wheel operable in the detecting means of FIGS. 5 and 6; FIG. 8 is a view from above schematically illustrating another encoder wheel that can be used in the detection means of Figures 5 and 6, - Figure 9 schematically illustrates a fourth embodiment of the detecting means of the wedging device, in a sectional view transverse, and - Figure 10 schematically illustrates a fifth embodiment of the detecting means of the wedging device, in a cross-sectional view.

  The attached drawings may not only serve to complete the invention, but also contribute to its definition, if any.

  The invention relates to a device for setting a rectifier (s) for pivoting flows of a turbojet compressor.

  We first refer to Figure 1 to specify the location of implantation of a wedging device according to the invention.

  In an axial turbojet engine, a compressor, for example a high-pressure compressor CHP as shown in FIG. 1, comprising a plurality of stages has the function of compressing the gases before combustion in the combustion chamber CC.

  Each stage is composed of a rotating wheel intended to accelerate the axial flow, the wheel bearing blades A, and a fixed blade crown called flow rectifier R intended to produce the pressure elevation.

  The blades A of the moving wheels and the vanes of the flow rectifiers R are housed in a chamber 1 delimited by a housing 2. These rectifiers R are rotatably mounted on the casing 2 of the compressor CHP in order to be wedged (or oriented). in positions optimizing flow guidance by wedging devices, partially shown. More specifically, although this does not appear in the figure, several rectifiers R are generally installed between two stages of blades A, and their angular positions are managed by the same wedging device.

  As best illustrated in FIG. 2, each rectifier R comprises an axis of rotation 3 to which a link 4 secured to a driving ring 5 is firmly fixed. Each ring 5 is itself attached to a jack 6 with variable stroke . Moreover, all the rectifiers R, installed between two stages of blades A, are attached to the same ring 5. They thus constitute, so to speak, floors. The displacement of a ring 5, with the aid of the associated jack 6, therefore causes the angular displacement of all the rectifiers R of a stage.

  The value of the stroke of a jack 6, and thus the angular position of the staggering rectifiers R of a stage, is determined at each instant by a processing module 7 as a function of the required performance of the turbojet engine and angular position measurements. performed by a detection device on at least one of the rectifiers R of a stage, as will be seen below.

  The rods 4, secured to the rectifiers R of the same stage, the ring 5 and the jack 6 associated constitute the driving means of a wedging device, while the detection device and the processing module 7 constitute the means control of this rigging device.

  According to the invention, the device for detecting the wedging device comprises, firstly, a light source 8, and secondly, light-conveying means 10 responsible for delivering light at the light source. of an illumination zone 11, a third part, an encoder element 12 secured to the axis of rotation 3 of one of the rectifiers R in the illumination zone 11 and responsible for interacting with the light illumination for generating optical signals representative of the angular position of the rectifier 5, and fourthly, means 13 responsible for collecting the optical signals to deliver them to the processing module 7.

  Preferably, the light source 8 is remotely implanted in a housing 9 which also houses the treatment module 7. Furthermore, the light-conveying means 10 are preferably made in the form of one or several optical fibers.

  Because of the detection mode used, it is preferable that at least part of the encoder element 12, the downstream end of the optical fiber 10 and at least a portion of the collection means 13 are housed in an enclosure 14 waterproof to light. Thus, the optical measurements are not disturbed by stray light, or by any dust or possible residues, particularly greasy, present in the turbojet engine.

  As is better illustrated in FIG. 3, the encoder element 12 is preferentially in the form of an encoder wheel, and more preferably still an encoder wheel portion. This comprises at least one range 15 arranged to allow the generation of variable optical signals as a function of its position within the illumination zone 11, and therefore as a function of the angular position of the rectifier R to the axis 3 of which it is solidarized.

  The detection can take place either by reflection or by transmission.

  An exemplary embodiment adapted to reflection detection is illustrated in FIG. 4.

  Here, the range 15 of the coding wheel portion 12 comprises a plurality of reflecting elements 16 whose dimensions and / or patterns differ so that the reflected light intensity varies according to its angular position. These reflecting elements 16, of three-dimensional type, can be made by selective deposition or by etching, or by photolithography or any other known technique.

  The illumination light is delivered at the level of the illumination zone 11 by the downstream end of the optical supply fiber 10, then reflected by the reflective elements 16, and finally collected by the upstream end of a light source. or a plurality of collection optical fibers 13a. This (these) optical fiber (s) collects (s) then the reflected light and collected (or collected optical signals) at the housing 9 where it is (they are) the subject of a measurement of intensity, for example using a photoelectric converter of the processing module 7. The processing module 7 is then arranged to convert the measured light intensity into a measurement of angular position. It may for example comprise for this purpose, in a memory, a correspondence table between light intensities and angular positions. Alternatively, it may comprise a circuit or a program responsible for calculating the position as a function of the measured intensity. Once the angular position has been measured, the processing module 7 can compare it to the optimum angular position to be taken by the rectifiers R of the stage it controls, so that the turbojet engine offers selected performances. The optimal angular position may be determined by the processing module 7, as a function of external instructions, or supplied to the processing module 7 by an external control module.

  If the comparison indicates that the rectifiers must be recalibrated, then the processing module 7 determines new angular position data, which it transmits to the jack 6 so that it changes its stroke accordingly.

  As schematically illustrated, the downstream end of the optical supply fiber 10 may be shaped to illuminate the illumination area 11 on a surface of selected dimensions, and the upstream end of the collection optical fiber 13a may be shaped to collect the reflected light on a surface of selected dimensions. But alternatively or additionally, it is also possible to provide between an end of optical fiber 10, 13a and the range 15 optical shaping means, such as a lens or a condenser. Instead of using reflective elements in the range 15, this may be treated so as to have a variable reflection coefficient, for example progressive from one of its ends to the other. In general, any means of reflection conferring on the range 15 a variable reflectivity can be envisaged. Furthermore, instead of using one or more collection optical fibers 13a, it would be possible to use photodetectors, for example of the CCD (Coupling Charge Device) type.

  Examples of embodiments adapted to transmission detection are illustrated in FIGS. 5 to 10.

  In the example illustrated in FIG. 5, the range 15 of the coding wheel portion 12 comprises at least one opening or slot 17 shaped so as to allow a variable amount of illumination light to pass according to the angular position of the encoder element. For this purpose, the slot 17 is for example progressive opening, as shown in Figure 7.

  But, as illustrated in Figure 8, the range 15 could include a plurality of slots 18 of variable shapes and / or spaced from each other with a variable pitch. Other achievements are also possible.

  To collect the light having crossed the beach 15 by its slot (s) 17 or 18, two solutions can be envisaged.

  A first solution, illustrated in FIG. 5, consists in placing under the coding wheel portion 12 a photoelectric conversion module 13b (or any other means making it possible to convert photons into a measurable physical quantity). This conversion module 13b, which thus directly assures the collection and conversion of the photons, is secured to the enclosure 14, for example by means of fixing lugs 19. The result of the conversion is transmitted by a cable 20 to the processing module 7, to serve for the development of new angular position data.

  A second solution, illustrated in FIG. 6, consists in placing under the coding wheel portion 12 one or more collection optical fibers 13a, of the type previously presented with reference to FIG. 4. The light (or optical signals collected) which has crossed the beach 15, by its slot or slots 17 or 18 (illustrated in FIGS. 7 and 8), is thus collected by the upstream end of the collection optical fiber 13a which routes it to the level of the housing 9 where it is (they are) the object of a measurement of intensity, for example by means of a photoelectric converter of the processing module 7. The processing module 7 is then arranged to convert the light intensity measured in a measurement of angular position. The result of the conversion is then used to develop the new angular position data. As in the example illustrated in FIG. 5, the slot or slits 17 or 18 formed at the level of the strip 15 may have any type of shape and any type of spacing as long as it (they) allows (tent) to vary the light intensity collected according to the position of the encoder wheel portion 12. Moreover, as indicated above, the downstream and upstream ends of the optical fiber feeds 10 and collection 13a can be shaped in order to deliver or collect illumination or reflected light on surfaces of selected dimensions. However, alternatively or in addition, it is also possible 30 between an end of optical fiber 10, 13a and the range 15 of optical shaping means, such as a lens or a condenser.

  Instead of transmitting the illumination light through slot (s) 17 or 18, it can be transmitted via variable reflectivity materials, provided or not with markings (or marks).

  For example, the range 15 of the coding wheel portion 12 may be made of a transparent material having a variable transmission coefficient. For this purpose, the range 15 may be treated so as to have an increasing transmission coefficient from one of its ends to the other. By way of example only, a glass material of variable thickness can be tinted in the mass according to a certain gradient. In this case, the collection may be carried out either with one or more collection optical fibers 13a or with a photoelectric conversion module 13b as previously discussed.

  In a variant, illustrated in FIG. 9, markings (or marks) 21 acting as local reflection means (in this case the material placed between adjacent markings is transparent) can be formed at the level of the mark. As local transmission means (in this case the material placed between adjacent markings is absorbent). These markings can be made by sandblasting, laser machining, etching or any other known marking technique. The markings 21 may have variable shapes and / or be spaced apart from each other by a variable pitch.

  As illustrated, the collection can be carried out using a photoelectric conversion module 13b (or any other means for converting photons into a measurable physical quantity), placed under the coding wheel portion 12. 13b conversion, which here ensures directly the collection and conversion of photons, is secured to the enclosure 14, for example by means of fastening tabs 19. The result of the conversion is transmitted by a cable 20 to the module 7, to be used in the development of the new angular position data.

  However, as in the previous embodiments, the transmitted light could be collected with one or more optical fibers 13a, possibly combined with optical shaping means.

  In another variant, illustrated in FIG. 10, markings (or marks) 21 constituting a graduated network of wide pitch (that is to say significantly greater than the wavelength of the light), and a condenser 22, secured to the chamber 14 by fixing lugs 23, followed by a scanning reticle 24, also secured to the enclosure, is provided upstream of the coding wheel portion 12. 14 by fixing lugs 25 and defining a graduated network 26 of narrow pitch. When the illumination light diffracted by the scanning reticle 24 5 encounters the wide-pitch grating 21, the diffracted components substantially coincide, so that a downstream of the coding wheel portion 12 a kind of "projection of light of the graduated structure 21.

  Any displacement of the coding wheel portion 12 with respect to the scan reticle 23 causes shadow / light modulations that can be detected by a photoelectric conversion module 13b, of the multi-element type, placed under said coding wheel portion 12. This module conversion 13b, which thus directly ensures the collection and conversion of photons, is secured to the enclosure 14, for example by means of fixing lugs 19. The result of the conversion is transmitted by a cable 15 to the processing module 7, for use in the development of the new angular position data.

  Detection of a neighboring type may also be considered in the case of reflection operation. In this case, a scanning reticle 20 defining a transparent phase grating interposed between the illumination light and the coding wheel portion 12, the range of which comprises a Diadur-type phase grating 9, and a module of FIG. photoelectric conversion 13b, of multi-element type, implanted opposite the track 15, on the opposite side to the illumination zone 11 and responsible for delivering electrical signals representative of the optical signals resulting from the interaction between the light of the light; illuminance, scan reticle and markings.

  This type of detector, called "diffraction and interference", is also marketed by the company Heidenhain.

  In the embodiments previously described, the angular position measurement can be either of absolute type or of relative type. In the case of a relative measurement, an absolute reference can be provided on the coding wheel 12, as well as on the possible scanning reticles 24, and a measurement of zero is preferably performed at each shutdown of the turbojet engine.

  The invention is not limited to the embodiments of chocking device described above, only by way of example, but it encompasses all the variants that may be considered by those skilled in the art within the scope of the claims below. after.

Claims (16)

claims   1. Swivel flow (s) rectifier (s) for a turbojet compressor (CHP), comprising drive means (4-6) adapted to drive at least one axis in rotation ( 3) of rectifier (R) so as to wedge it angularly according to position data delivered by control means (7-26), characterized in that said control means comprise illumination means (8, 10) adapted to deliver a light at an illumination region (11), an encoder element (12) secured to said rectifier axis (3) in said illumination zone and arranged to interact with said light to generate optical signals representative of the angular position of said rectifier (R), means (13) for collecting said optical signals, and processing means (7) arranged to determine angular position data from said collected optical signals. .   2. Device according to claim 1, characterized in that said encoder element (12) is arranged in the form of at least one coding wheel portion provided with at least one pad (15) configured to allow the generation variable optical signals according to its position in said illumination area (11).   3. Device according to one of claims 1 and 2, characterized in that said illumination means (8, 10) comprise at least one optical fiber (10) provided with an end shaped so as to illuminate said zone of light. illumination (11) on a surface of selected dimensions.   4. Device according to one of claims 2 and 3, characterized in that said range (15) comprises at least one slot (17,18) shaped to transmit said light differently according to the angular position of said encoder element (12). ).   5. Device according to claim 4, characterized in that said slot (17) is progressive opening.   6. Device according to claim 4, characterized in that said range (15) comprises a plurality of slots (18) of different shapes and / or spaced from each other by a variable pitch.   7. Device according to one of claims 2 and 3, characterized in that said range (15) is transparent and comprises at least one zone provided with markings (21).   8. Device according to claim 7, characterized in that it comprises a transparent scanning reticle (25) interposed between said illumination light and said encoder element (12) and in that said collection means (13) comprise photodetectors (13b) implanted opposite said range (15), on the opposite side to said illumination zone (11) and adapted to deliver electrical signals, representative of the optical signals resulting from the interaction between the illumination light , said scanning reticle (25) and said markings (21).   9. Device according to one of claims 4 to 7, characterized in that said collection means (13) comprise photodetectors (13b) implanted opposite said range (15), on the opposite side to said illumination zone ( 11) and adapted to deliver electrical signals, representative of the optical signals transmitted at said range.   10. Device according to one of claims 4 to 7, characterized in that said collection means (13) comprise at least one optical fiber (13a) provided with an end shaped to collect said optical signals transmitted at the level of said range (15). 30 11. Device according to one of claims 2 and 3, characterized in that said range (15) comprises at least one reflecting element (16) shaped to reflect said light differently according to the angular position of said encoder element (12).   12. Device according to claim 11, characterized in that it comprises a transparent scanning reticle interposed between said illumination light and said encoder element (12) and defining a transparent phase grating, in that said reflecting element comprises markings, and in that said collection means (13) comprise photodetectors implanted upstream of said scanning reticle and capable of delivering electrical signals, representative of the optical signals resulting from the interaction between the illumination light, said reticle scanning and said markings. 10 13. Device according to claim 11, characterized in that said collection means (13) comprise at least one optical fiber (13a) provided with an end shaped so as to collect said reflected optical signals at said range (15). .   14. Device according to one of claims 1 to 13, characterized in that at least part of said encoder element (12), part of said illumination means (10) and at least part of said collection means (13a , 13b) are housed in a chamber (14) sealed against light. 20 15. Device according to one of claims 1 to 14, characterized in that said processing means (7) are housed in a housing (9) remote from said rectifier (R).   16. Device according to one of the preceding claims, characterized in that said drive means (4-6) comprises a ring (5) attached by a multiplicity of rods (4) to a multiplicity of rectifiers (R), and a jack (6) adapted to actuate said ring gear (5) so as to block said multiplicity of rectifiers (R) in selected angular positions as a function of said angular position data determined by said processing means (7).