Calibration angle measuring device and associated calibration angle measuring method

Abstract

Angle-of-cut measurement device and associated angle-of-cut measurement method. One aspect of the invention relates to a device for measuring the angle of cut of turbine blades of a turbomachine with a first X-axis, comprising: - a movable wheel centered on the first X-axis equipped with a plurality of blades arranged radially around the first X-axis, each blade having a foot at which it is mounted to pivot about a second radial Y-axis of pivoting, - a fixed frame with X-axis, comprising at least one set of fixed magnetic sensors perpendicular to the first X-axis, - the movable wheel comprising a first magnetic target, the magnetic target being fixed on the movable wheel, each blade having a profile oriented along a third Z-axis, - a first magnetic needle fixed on a first blade and forming a first angle alpha with the third axis of the first blade, the first magnetic target serving as a reference for the first blade.The measuring device comprises a second magnetic needle fixed to a second blade and forming a second angle beta with the third axis of the second blade, the second angle beta being different from the first angle alpha. Figure to be published with the abbreviation: Figure 10b,

Description

Title of the invention: Device for measuring the setting angle and associated method for measuring the setting angle TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of variable-pitch blades in turbomachines. The invention finds a particular application in the field of aeronautics, in particular for the blades of turbojets or turboprops of aircraft.

[0002] The present invention relates to the measurement of the pitch angle of blades and in particular to a pitch angle measuring device and a pitch angle measuring method using this device. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] [Fig. 1] represents a turbomachine 1 with a first axis X with, from upstream to downstream, a fan module 2 and a double-body gas generator formed of a first compressor 3, a second compressor 4, a combustion chamber 5, and two turbines in series 6 and 7. The fan module 2 is mounted on a fixed frame 80 of first axis X and is composed of a movable wheel 21 centered on the first axis X. During operation of the turbomachine 1, the movable wheel rotates about the first axis X. The movable wheel is provided with a plurality of blades 22 arranged radially around the first axis X. As illustrated in [Fig. 2], each blade 22 has a root 22a at which it is pivotally mounted about a second radial pivot axis Y. Thus, in addition to its rotation around the X axis in solidarity with the moving wheel 21, each blade 22 pivots around the second radial pivot axis Y.This pivoting movement corresponds to a change in the pitch angle of each blade 22. The pivoting is controlled according to flight requirements.

[0004] The pitch angle of a blade 22 corresponds to the orientation of the blade 22 relative to the axis X of the turbomachine 1. As illustrated in [Fig. 3], the first axis X of the turbomachine 1 corresponds to the direction of flow of the gases circulating in the turbomachine, represented by the arrow F. When a blade 22 is in the “flag” position, represented by the line Pd, it lets the gases flow and its pitch angle is 90°, relative to a tangential straight line A. When the blade 22 is in the “reverse” position, represented by the line Pr, its pitch is reversed and reverses the direction of flow of the gases around the blade 22. The pitch angle is then within an angular range of negative angles ranging from approximately 0 degrees to -20 degrees. Between these two positions, the blade is in a pitch position Pv called flight pitch. In systems with variable pitch angle, measuring the pitch angle of the blades allows it to be controlled and adjusted accordingly according to flight requirements.

[0005] There are devices for measuring the pitch angle using needles made of ferromagnetic material coupled to magnetic sensors. An example of this type of solution is illustrated in Figures 4 and 5. A magnetic needle 110, fixed to the root 22a of a blade 22 whose pitch angle is measured, passes in front of a fixed sensor 120, which then detects a variation in the magnetic field. The analysis of the signal detected by the fixed sensor 120 makes it possible, by using reference signals corresponding to the detection of an absolute reference target 13 and relative reference targets 14, to determine the pitch angle of the blade.

[0006] However, the angular measurement range of this type of device is often limited by the architecture of the turbomachine. Indeed, as illustrated in [Fig. 6], there is a measurement blind spot 0M due to the physical limits of the detection field of the fixed sensor 120, and the constraints on the length of the magnetic needle 110 imposed by the positioning of the other components of the turbomachine. For example, in [Fig. 6], the magnetic needle 110 no longer passes into the detection field of the fixed sensor 120 for the positions between the positions Pd and PVo of the blade 22, corresponding to the positions of the magnetic needle 110d and 1 lOVo- Typically, the range of pitch angles between 60 and 90 degrees is not measurable.

[0007] Generally speaking, it is impossible, with certain turbojet architectures, to measure the entire angular range covering the pitch angles between the “flag” position and the “reverse” position. However, it is advantageous to measure all the blade pitch positions. For example, when starting the turbojet, the blades are typically in the “flag” position. However, it is possible that this position is not measurable in the case where the position of the corresponding magnetic needle 110 is in a dead angle of the fixed sensor 120. Summary of the invention

[0008] The invention offers a solution to the problems mentioned above, by making it possible to widen the range of measurement of the setting angle, in order to improve the control of this parameter.

[0009] A first aspect of the invention relates to a device for measuring the pitch angle of blades of a turbomachine with a first axis X, comprising: - a mobile wheel centered on the first axis X provided with a plurality of blades arranged radially around the first axis X, each blade having a root at which it is pivotally mounted around a second radial pivot axis Y, - a fixed X-axis frame, comprising at least one set of fixed magnetic sensors perpendicular to the first X-axis, - the moving wheel comprising a first magnetic target, the magnetic target being fixed on the moving wheel, each blade having a profile oriented along a third axis Z, - a first magnetic needle fixed on a first blade and forming a first angle alpha with the third axis of the first blade, the first magnetic target serving as a reference for the first blade, the measuring device comprising a second magnetic needle fixed on a second blade and forming a second angle beta with the third axis of the second blade, the second angle beta being different from the first angle alpha.

[0010] Thanks to the invention, the angular range of measurement of the setting angle is widened. It is possible to measure setting angles corresponding to extreme blade setting positions such as the "flag" position and the "reverse" position, due to the offset between the first magnetic needle and the second magnetic needle.

[0011] Advantageously, the second angle beta is between alpha +20 degrees and alpha + 50 degrees. Thus, an angular range of measurement of the setting angle of up to 110 degrees can be achieved.

[0012] Advantageously, the first angle alpha is between 70 degrees and 130 degrees. The value of the first angle alpha depends on the angular range of measurement of the setting angle. Indeed, in the flag position Pd, the setting angle can be equal to 85 or 90 degrees relative to the tangential line A. In the “reverse” position Pr, the setting angle can be equal to -5 degrees or -15 degrees. This range of values ​​makes it possible to arrange the first magnetic needle and the second magnetic needle so that they can pass into the detection field of magnetic sensors.

[0013] In a first embodiment, the moving wheel comprises a second magnetic target serving as a reference for the second blade, the first blade and the second blade are successive, and the at least one set of fixed magnetic sensors consists of a single set of magnetic sensors. This configuration makes it possible to reduce the number of needles to be installed on at least some of the blades of the turbine.

[0014] In a second embodiment, the first blade and the second blade are merged and the fixed frame comprises a first set and a second set of fixed magnetic sensors perpendicular to the first axis X. This configuration makes it possible to measure the pitch angle of each blade of the turbine regardless of the value of the pitch angle in the angular measurement range.

[0015] In the second embodiment, the first magnetic needle and the second magnetic needle are of the same length. This configuration makes it possible to strengthen the redundancy of the measuring system and improve the accuracy of the setting angle measurement.

[0016] In a variant of the second embodiment, the first magnetic needle and the second magnetic needle have different lengths. This configuration makes it possible to balance the redundancy of the measuring system while maintaining an extended angular range of setting angle measurement.

[0017] Advantageously, the first magnetic needle and the second magnetic needle have different shapes. This configuration facilitates the processing of the signals by the processing unit.

[0018] A second aspect of the invention relates to a method for measuring the pitch angle of a blade of a turbomachine by the measuring device according to the first embodiment, the measuring device further comprising a processing unit, the method comprising: - either a single detection step (Ela), by the single set of magnetic sensors, of a single variation in magnetic field, - either a multiple detection step (Elb), by the single set of magnetic sensors, of a first variation in magnetic field and a second variation in magnetic field, Or : - if the method includes the single detection step (Ela), the single variation in magnetic field corresponds to the passage of the first magnetic needle or the second magnetic needle near the single row of sensors, - if the method comprises the multiple detection step (Elb) the first variation in magnetic field corresponds to the passage of the first magnetic needle near the single set of sensors and the second variation in magnetic field corresponds to the passage of the second magnetic needle near the single set of sensors, and where the method comprises, following the single detection step (Ela) or the multiple detection step (Elb), a step of calculating the setting angle (E4) by the processing unit on the basis of an electrical signal representative of a variation in magnetic field.

[0019] A third aspect of the invention relates to a method for measuring the pitch angle of a blade of a turbomachine by a measuring device according to the second embodiment or its variant, the measuring device further comprising a processing unit, the method comprising: - either a single detection step (E2a), by the first set of magnetic sensors or by the second set of magnetic sensors, of a single variation in magnetic field, - either a multiple detection step (E2b) of a first variation in magnetic field by the first set of magnetic sensors and of a second variation in magnetic field by the second set of magnetic sensors, where: - if the method comprises the single detection step (E2a), the single variation in magnetic field corresponds to the passage of either the first magnetic needle near the first set of magnetic sensors or the second magnetic needle near the second set of sensors, - if the method comprises the multiple detection step (E2b) the first variation in magnetic field corresponds to the passage of the first magnetic needle near the first set of sensors and the second variation in magnetic field corresponds to the passage of the second magnetic needle near the second set of sensors, and where the method comprises, following the single detection step (E2a) or the multiple detection step (E2b), a step of calculating the setting angle (E5) by the processing unit on the basis of an electrical signal representative of a variation in magnetic field.

[0020] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0021] The figures are presented for information purposes only and in no way limit the invention. - [Fig.l] shows a schematic representation of a turbomachine according to the prior art. - [Fig.2] shows a blade root of a variable-pitch turbomachine according to the prior art. - [Fig.3] represents different pitch positions of a turbomachine blade. - [Fig.4] represents a three-dimensional view of a device for measuring the blade pitch angle of a turbomachine according to the prior art. - [Fig.5] is a cross-section of the turbomachine blade pitch angle measuring device of [Fig.4]. - [Fig.6] is an illustration of a measurement blind spot in a turbomachine blade pitch angle measuring device according to the prior art. - [Fig.7] represents the direction of a third axis defined by each of the turbomachine blades according to the invention are oriented. - [Fig.8a] and [Fig.8b] schematically illustrate the positioning of a first magnetic needle and a second magnetic needle according to the invention. - [Fig.9a] and [Fig.9b] represent a device for measuring the setting angle according to a first embodiment of the invention. - [Fig.10a], [Fig.10b], [Fig.10c] and [Fig.10d] represent, for different blade pitch angles, a pitch angle measuring device according to a second embodiment of the invention. - [Fig.11a], [Fig.11b], [Fig.11c] and [Fig.11d] represent, for different blade pitch angles, a pitch angle measuring device according to a variant of the second embodiment of the invention. - [Fig. 12] schematically represents, for different blade pitch angles, an example of a signal received by a processing unit of the pitch angle measuring device according to the first embodiment of the invention. - [Fig. 13] schematically represents, for different blade pitch angles, examples of signals received by the processing unit of the pitch angle measuring device according to the second embodiment of the invention. - [Fig. 14] schematically represents, for different blade pitch angles, examples of signals received by the processing unit of the pitch angle measuring device according to the variant of the second embodiment of the invention. DETAILED DESCRIPTION

[0022] The figures are presented for information purposes only and in no way limit the invention.

[0023] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0024] The present invention proposes to widen the range of measurement of the pitch angle of variable-pitch blades of a turbomachine by using a combination of magnetic needles fixed on the blades. As will be described later, this widening will be achieved by an angular offset of the magnetic needles.

[0025] Here we consider a turbomachine 1, of the turbojet type, comprising the components of [Fig.l], and in particular the fan module 2 comprising the movable wheel 21 and the blades 22. The first compressor 3 is connected by a turbine shaft 71 of axis X to the turbine 7 to form a low-pressure body. The second compressor 4 is connected by a shaft 61, of axis X, to the turbine 6 to form a high-pressure body. The fixed structural members of the turbomachine comprise an inlet casing 8 located upstream of the gas generator between the fan module 2 and the compressor 3, the inter-compressor casing 9 between the compressor 3 and the compressor 4. Downstream, the transmission of the forces from the engine to the suspension is ensured by an exhaust casing 10. The movable wheel 21 is integral with a rotor of the compressor 3 rotatably mounted in the inlet casing 8.

[0026] Each blade 22 defines the direction of a third Z axis, as illustrated in [Fig.7].

[0027] Magnetic needles 11 are fixed at the feet of at least some of the blades 22 of the moving wheel 21. In other words, a blade 22 of the moving wheel 21 comprises a magnetic needle 11, or two magnetic needles 11, or none. There are at least two magnetic needles 11, carried either by the same blade 22 of the moving wheel 21, or by two different blades. There may be magnetic needles 11 on some blades 22 of the moving wheel 21 or even on all the blades 22 of the moving wheel 21. The magnetic needles 11 are divided into a first sub-assembly comprising at least one magnetic needle 11A, hereinafter referred to as a type A needle, and a second sub-assembly comprising at least one magnetic needle 11B, hereinafter referred to as a type B needle.

[0028] A processing unit is provided for receiving and processing electrical signals from magnetic sensors which will be described later.

[0029] Each needle 11A of type A forms a first angle alpha with the third axis Z of the blade at the root of which it is fixed, as illustrated in [Fig.8a]. Each needle 11B of type B forms a second angle beta, with the third axis Z of the blade at the root of which it is fixed, as illustrated in [Fig.8b]. The second angle beta is different from the first angle alpha. For example, the first angle alpha has a value between 70 and 130 degrees. For example, the second angle beta is between alpha+20 degrees and alpha+50 degrees.

[0030] The mobile wheel 21 comprises a magnetic reference target 13, fixed on the mobile wheel 21 and serving as an absolute azimuthal reference. The magnetic reference target has a typical shape, for example comprising three claws, so as to generate an identifiable magnetic field variation when it passes in front of the magnetic sensors previously mentioned and which will be described later, when the mobile wheel 21 rotates around the X axis. The magnetic reference target makes it possible in particular to count the number of revolutions.

[0031] Furthermore, the mobile wheel 21 comprises relative magnetic targets 14, fixed on the mobile wheel 21 and serving as relative azimuthal markers making it possible to identify certain blades 22 of the mobile wheel 21 on the electrical signals received by the processing unit as will be seen later. The relative magnetic targets 14 also have a typical shape, for example comprising two claws, so as to generate an identifiable magnetic field variation when they pass in front of the previously mentioned magnetic sensors, when the mobile wheel 21 rotates around the first axis X.

[0032] In a first embodiment of the blade pitch angle measuring device according to the invention, illustrated in FIGS. 9a and 9b, the fixed frame 80 comprises a single row of magnetic sensors 12. For example, the row of magnetic sensors comprises 4 magnetic sensors. The row of magnetic sensors 12 is perpendicular to the first X axis.

[0033] The magnetic sensors of the row of magnetic sensors 12 all detect the same signal when a magnetic needle 11A, 11B passes through their detection field. This same signal is representative of the variation in magnetic field induced by the magnetic needle 11A, 11B passing through the detection field of the row of magnetic sensors 12. Thus, this plurality of magnetic sensors ensures redundancy of the received signal, as well as the reception thereof in the case, for example, where a sensor of the row of magnetic sensors 12 is defective. The signal received by the row of magnetic sensors 12 is transmitted to the processing unit. Typically, the signal is an electrical voltage peak. Preferably, the needles 11A, 11B are identical. This configuration makes it possible not to require different needle heads.

[0034] In this embodiment, a needle 1 IA of type A is fixed on the root of at least one blade 22 of the moving wheel 21, and a needle 1 IB of type B is fixed on the root 22a of the blade following the at least one blade on the moving wheel 21. The blades carrying needles of type A are called in this embodiment blades of type A and the blades carrying needles of type B are called blades of type B.

[0035] In Figures 9a and 9b, the passage of a blade of type A and a blade of type B in the detection field of the row of magnetic sensors 12 is observed. The setting angle of the blade of type A and the setting angle of the blade of type B are identical. For example, in [Fig.9a], it can be observed that the needle 1 1A, fixed on a first blade, passes to the limit of the detection field of the row of magnetic sensors 12. Furthermore, as visible in [Fig.9b], due to the offset between the first angle alpha and the second angle beta, the needle 1 1B fixed on a successive blade passes into the detection field of the row of magnetic sensors 12 but more in the center of the detection field in comparison with [Fig.9a].

[0036] In a second embodiment of the blade pitch angle measuring device according to the invention illustrated in FIGS. 10a, 10b, 10c and 10d, the fixed frame 21 comprises a first row of magnetic sensors 12A and a second row of magnetic sensors 12B separate from the first row of magnetic sensors 12A. For example, each of the first row of magnetic sensors 12A and the second row of magnetic sensors 12B comprises 4 magnetic sensors.

[0037] The first row of magnetic sensors 12A and the second row of magnetic sensors 12B are perpendicular to the first axis X. The first row of magnetic sensors 12A and the second row of magnetic sensors 12B are axially offset along the first axis X. Different blade setting positions 22 are shown in FIGS. 10a, 10b, 10c and 10d.

[0038] Furthermore, the processing unit comprises a first module and a second module.

[0039] The magnetic sensors of the first row of magnetic sensors 12A of FIGS. 10a, 10b, 10c and 10d detect a first signal, identical for each of the sensors, as a magnetic needle 11A, 11B passes through the detection field of the first row of magnetic sensors 12A. Thus, this plurality of magnetic sensors ensures redundancy of the received signal, as well as the reception thereof in the case, for example, where a sensor of the first row of magnetic sensors 12A is defective, or where the magnetic needle 11A, 11B is not in the detection field of a sensor. The first signal is representative of the variation in magnetic field induced by the magnetic needle 11A, 11B passing through the detection field of the first row of magnetic sensors 12A. The first signal is transmitted and received by the first module of the processing unit. Typically, the first signal is an electrical voltage spike.

[0040] The magnetic sensors of the second row of magnetic sensors 12B of FIGS. 10a, 10b, 10c and 10d detect a second signal, identical for each of the sensors, as a magnetic needle 11A, 11B passes through the detection field of the second row of magnetic sensors 12B. Thus, this plurality of magnetic sensors ensures redundancy of the received signal, as well as the reception thereof in the case, for example, where a sensor of the second row of magnetic sensors 12B is defective, or where the magnetic needle 11A, 11B is not in the detection field of a sensor. The second signal is representative of the variation in magnetic field induced by the magnetic needle 11A, 11B passing through the detection field. The second signal is transmitted and received by the second module of the processing unit. Typically, the second signal is an electrical voltage peak.

[0041] In this embodiment, at least one blade 22 of the moving wheel 21 comprises a needle 11A of type A and a needle 11B of type B. The needles 11A of type A and the needles 11B of type B have the same length.

[0042] In [Fig. 10a], only the needle 1 IB passes into the field of the first row of magnetic sensors 12A and into that of the second row of magnetic sensors 12B.

[0043] In [Fig. 10b], needle 1 IA and needle 1 1B both pass through the field of the first row of magnetic sensors 12A and through that of the second row of magnetic sensors 12B.

[0044] In [Fig. 10c], only needle 1 IA passes into the field of the first row of magnetic sensors 12A and into that of the second row of magnetic sensors 12B.

[0045] In [Fig.10d], only needle 1 IA passes into the field of the first row of magnetic sensors 12A.

[0046] In a variant of the second embodiment of the blade setting angle measuring device according to the invention illustrated in FIGS. 11a, 11b, 11c and 11d, a needle 11A of type A has a first length 11 and a needle 11B of type B has a second length 12 longer than the first length 11. Thus, a needle 11A of type A passes only in the detection field of the first row of sensors 12A. Also, a needle 11B of type B passes both in the detection field of the first row of sensors 12A and in that of the second row of magnetic sensors 12B. Different blade setting positions 22 are shown in FIGS. 10a, 10b, 10c and 10d.

[0047] In [Fig. 1 la], only the needle 1 IB passes into the field of the second row of magnetic sensors 12B.

[0048] In [Fig. 11b], the needle 1 IA is not detected. The needle 1 IB passes both into the detection field of the first row of magnetic sensors 12A and into that of the second row of magnetic sensors 12B.

[0049] In [Fig. 1 le], the needle 1 IA does not pass into the field of the second row of magnetic sensors 12B, but into that of the first row of magnetic sensors 12A.

[0050] In [Fig. 1 Id], only needle 1 IA passes into the field of the first row of magnetic sensors 12A.

[0051] Thus, the setting angle measuring device according to the invention makes it possible to measure setting angles over a wider angular range than in the prior art, typically an angular range of between 100 and 110 degrees, thanks to the offset between the first angle alpha and the second angle beta. Indeed, this offset makes it possible to define three angular measurement sub-ranges, the ends of which can reach values ​​corresponding to the extreme setting positions of the blades 22, namely the “flag” position and the “reverse” position.

[0052] A method for measuring the pitch angle of a blade with a variable pitch angle according to the invention will be described below. When flying, a modification of the pitch angles of the blades 22 is actuated, all the blades 22 are pivoted about their second radial pivot axis Y by the same angle.

[0053] In operation, the pitch angle of the blades 22 of the fan module 2 varies over an angular range [0i; 02] between the “reverse” position (corresponding to the pitch angle 00) and the “flag” position (corresponding to the pitch angle 02).

[0054] The angular range [0i; 02] is divided into three sub-ranges: a first angular range [0i; ô] where only a type A needle 1 IA is detected; a so-called “multiple range” range [ô;y] where a type A needle 11A and a type B needle 1 IB are detected; and a second angular range [y; 02] where only a type B needle 1 IB is detected.

[0055] For example, the range [01;02] is equal to [-20;90 degrees]. For example, if the first angular range [01;δ], is equal to [-20;30 degrees], the offset between the first angle alpha and the second angle beta can be chosen equal to 50 degrees. Thus, the second angular range [δ;δ], is equal to [40;90 degrees].

[0056] We note q> the common pitch angle of the blades.

[0057] It is further assumed that the reference magnetic target 13 has a shape with three claws and that the relative magnetic targets 14 have a shape with two claws.

[0058] A first embodiment of the method, carried out by the first embodiment of the blade pitch angle measuring device according to the invention, is described below. Two successive blades of the moving wheel 21 are respectively a type A blade and a type B blade.

[0059] If the common setting angle q> to be measured is included in the first angular range [0i; ô], a needle 1 IA of type A is detected by the row of magnetic sensors 12 when the corresponding blade passes in front of the row of magnetic sensors 12.

[0060] If the common setting angle q> to be measured is within the multiple range [ô ;y], a needle 11A of type A and a needle of type B are detected by the row of magnetic sensors 12 when the corresponding blades pass in front of the row of magnetic sensors 12.

[0061] If the common setting angle q> to be measured is included in the second angular range [y; 02], a needle 1 IB of type B is detected by the row of magnetic sensors 12 when the corresponding blade passes in front of the row of magnetic sensors 12.

[0062] In operation, the mobile wheel 21 rotates around the X axis. The row of magnetic sensors 12 detects, in real time, the reference magnetic target 13, the relative magnetic targets 14, and at least one needle 11A of type A or 11B of type B which pass into its detection field.

[0063] When the reference magnetic target passes into the detection field of the row of magnetic sensors 12, the processing unit receives an absolute reference signal formed of three successive peaks PABsi, Pabs2 and PABs3, due to the three magnetic field variations created successively by the three claws of the reference magnetic target.

[0064] When a relative magnetic target 14 passes into the detection field of the row of magnetic sensors 12, the processing unit receives a relative reference signal formed of two successive peaks Prel1 and PreL2, due to the two variations in magnetic field created successively by the two claws of said secondary target.

[0065] When a current blade 22 comprising a needle 11A, 11B, and in particular its root 22a, passes in front of the row of sensors 12, two configurations are possible, depending on the value of the common setting angle q>.

[0066] If the current blade 22 is a blade of type A, the processing unit will receive a signal from the row of magnetic sensors 12 only in the case where the needle 1 IA of type A fixed to the root of the blade passes into the detection field of the row of magnetic sensors 12. In other words, the processing unit will receive a signal in the case where the common setting angle q> is included either in the first angular range [0i; y], or in the multiple range [ô; y]. Otherwise, that is to say if the common setting angle q> is included in the angular range [y; 02], the processing unit will not receive a signal.

[0067] However, the successive blade, that is to say following the current blade 22 on the moving wheel 21, when the latter continues its rotation around the axis X, is a blade of type B. Thus, during the passage of the successive blade, if the common setting angle q> is included in the angular range [y; 02], the processing unit will receive a signal from the row of magnetic sensors 12 due to the detection of the needle 11B of type B in the detection field of the row of magnetic sensors.

[0068] [Fig. 12] is a schematic representation of different types of signals received by the processing unit for different values ​​of the common setting angle q>.

[0069] When the common setting angle q> to be measured is included in the range [y; 02], illustrated by a value equal to 90 degrees, that is to say, the blades 22 of the moving wheel 21 are in the “flag” position, the processing unit receives, between two relative reference signals, a peak PB corresponding to the passage of a needle 1 IB of type B. The time shift between the relative reference signal formed by the peaks Preli and PREL2 and the peak PB makes it possible to calculate the common setting angle q> from geometric and kinematic parameters of the turbomachine.

[0070] The geometric and kinematic parameters of the turbomachine are for example the distance from the X axis to the outside diameter of the moving wheel 21, corresponding to the support zone of the blade roots 22a, the angle between the reference magnetic target and the secondary target corresponding to the relative reference signal formed by the peaks PRELi and P Rfi .2, the position of the row of magnetic sensors 12 relative to the root 22a of the blade 22 passing in its field, and the rotation speed of the moving wheel 21.

[0071] When the common setting angle q> to be measured is included in the multiple range [ô ;y], illustrated in [Fig. 12] by values ​​equal to 30 or 40 degrees, the processing unit receives, between two secondary reference signals, a first peak PA, then a second peak PB. The first peak PA corresponds to the passage in the detection field of the row of sensors 12 of a blade of type A and the second peak PB corresponds to the passage in the detection field of the row of sensors 12 of the type B blade succeeding the type A blade on the moving wheel 21. The time shift between the first peak and the second peak corresponds to the angular shift between the type A blade and the type B blade succeeding it.

[0072] When the common setting angle q> to be measured is included in the range [0i; y], illustrated in [Fig. 12] by a value equal to 0 degrees, that is to say, the blades 22 of the moving wheel 21 are close to the “reverse” position, the processing unit receives, between two relative reference signals, a peak PA corresponding to the passage of a needle 11A of type A. The time shift between the relative reference signal formed by the peaks Preli and PREL2 and the peak PB makes it possible to calculate the common setting angle q> from the geometric and kinematic parameters of the turbomachine 1.

[0073] The position of the relative reference signal formed of the peaks PRELi and PRE,i,2 makes it possible, by counting from the last absolute reference signal formed of the peaks Pabsu Pabs2 and P ABs3 previously received by the processing unit, to identify the blades 22 of the moving wheel 21 which generated the peaks PA and PB.

[0074] A second embodiment of the method, carried out by the second embodiment of the blade pitch angle measuring device according to the invention, is described below.

[0075] At least one blade 22 of the moving wheel 21 comprises a needle 1 IA of type A and a needle 1 IB of type B. A needle 1 IA of type A and a needle 1 IB of type B have the same length.

[0076] If the common setting angle q> is included in the first angular range [0i; ô], only a needle 11A of type A is detected by the first row of magnetic sensors 12A and by the second row of magnetic sensors 12B when the corresponding blade 22 passes through their detection field.

[0077] If the common setting angle q> is included in the multiple range [ô ;y], a needle 11A of type A and a needle 11B of type B are detected by the first row of magnetic sensors 12A and by the second row of magnetic sensors 12B when the corresponding blades 22 pass through their detection field.

[0078] If the common setting angle q> is included in the second angular range [y; 02], only a needle 1 IB of type B is detected by the first row of magnetic sensors and by the second row of magnetic sensors 12B when the corresponding blade 22 passes through their detection field.

[0079] [Fig. 13] is a schematic representation of different types of signals received by the processing unit for different values ​​of the common setting angle q>.

[0080] For each value of the common setting angle q> illustrated, a first signal a and a second signal b are represented. The first signal a corresponds to the signal received by the first row of magnetic sensors 12A. The second signal b corresponds to the signal received by the second row of magnetic sensors 12B.

[0081] When the common setting angle q> to be measured is included in the second angular range [y; 02], illustrated in [Fig. 13] by a value equal to 90 degrees, that is to say that the blades of the moving wheel 21 are in the “flag” position, the first module of the processing unit receives the first signal a, which comprises, between two relative reference signals, a primary peak PBi corresponding to the passage of a needle 1 IB of type B. A second module of the processing unit receives the second signal b, which comprises, between two relative reference signals, a secondary peak PB2 corresponding to the passage of the needle 1 IB.

[0082] There is a time shift At, illustrated in [Fig. 13], between the primary peak PBi and the secondary peak PB2. This time shift At is due to the fact that the first row of magnetic sensors 12A and the second row of magnetic sensors 12B are axially offset along the X axis. Thus, the distance between the first row of magnetic sensors 12A and the root 22a of the blade 22 passing through its detection field is different from the distance between the second row of magnetic sensors 12B and the root 22a of said blade 22. In other words, the first row of magnetic sensors 12A and the second row of magnetic sensors 12B do not detect at the same time the variation in magnetic field induced by the passage of the needle 11B through their respective detection fields.

[0083] The time shift between the relative reference signal formed by the peaks PRELi and PREL2 and the primary peak PBi in the first signal a, on the one hand, and that between the relative reference signal formed by the peaks PRELi and PRu,2 and the secondary peak PB2 in the second signal b, makes it possible to calculate the common setting angle q> twice from geometric and kinematic parameters of the turbomachine 1, as in the first embodiment. Thus, the precision of calculation of the common setting angle q> is increased.

[0084] When the common setting angle q> to be measured is included in the multiple range [ô ;y], illustrated in [Fig. 13] by values ​​equal to 30 or 40 degrees, the first module of the processing unit receives the first signal a. The first signal a comprises, between two relative reference signals, a first primary peak PAB then a second primary peak PBi. The first primary peak PAi corresponds to the passage in the detection field of the first row of sensors 12A of the needle 1 IA of type A of the blade 22 facing the first row of sensors 12A. The second primary peak PBi corresponds to the passage in the detection field of the first row of sensors 12A of the needle 1 IB of type B of said blade 22. The time shift between the first peak PA[ and the second peak PBi corresponds to the angular shift between the needle 1 IA of type A and the needle 1 IB of type B of the blade 22.

[0085] The second module of the processing unit receives the second signal b. The second signal b comprises, between two relative reference signals, a first peak secondary peak PA2, then a second secondary peak PB2. The first secondary peak PA2 corresponds to the passage in the detection field of the second row of sensors 12B of the needle 1 IA of type A of the blade 22 when it faces the second row of sensors 12B. The second secondary peak PB2 corresponds to the passage in the detection field of the second row of sensors 12B of the needle 1 IB of type B of said blade. The time shift between the first peak PA2 and the second peak PB2 corresponds to the angular shift between the needle of 1 IA type A and the needle IB of type B of the blade.

[0086] Four measurements of the common setting angle q> are thus obtained: two measurements originating from the detection of the variation in magnetic field induced by the needle 1 IA of type A of a current blade 22, by the first row of magnetic sensors 12A and the second row of magnetic sensors 12B respectively, and originating from the detection of the variation in magnetic field induced by the needle 1 1B of type B of said current blade 22, by the first row of magnetic sensors 12A and the second row of magnetic sensors 12B respectively. Thus, the precision of calculation of the common setting angle q> is increased.

[0087] When the common setting angle q> to be measured is included in the first angular range [0i; y], illustrated in [Fig. 13] by a value equal to 0 degrees, that is to say that the blades 22 of the moving wheel 21 are close to the “reverse” position, the first module of the processing unit receives the first signal a. The first signal a comprises, between two relative reference signals, a primary peak PAi corresponding to the passage of a needle 1 IA of type A. The second module of the processing unit receives the second signal b, which comprises, between two relative reference signals, a secondary peak PA2 corresponding to the passage of the needle 1 IA.

[0088] The time shift observed in [Fig. 13] between the primary peak PAi and the secondary peak PA2 is due to the fact that the first row of magnetic sensors 12A and the second row of magnetic sensors 12B are axially offset along the X axis. Thus, the distance between the first row of magnetic sensors 12A and the root 22a of the blade 22 passing through its detection field is different from the distance between the second row of magnetic sensors 12B and the root 22a of said blade 22. In other words, the first row of magnetic sensors 12A and the second row of magnetic sensors 12B do not detect at the same time the variation in magnetic field induced by the passage of the needle 1 IA through their respective detection fields.

[0089] The time shift between the relative reference signal formed by the peaks PRELi and PreL2 and the primary solid line peak PA[ in the first signal a, on the one hand, and between the relative reference signal formed by the peaks Preli and PREL2 and the secondary peak PA2 in the second signal b, makes it possible to calculate the common setting angle q> twice from of geometric and kinematic parameters of the turbomachine 1. Thus, the calculation accuracy of the common pitch angle q> is increased.

[0090] A variant of the second embodiment of the measuring method according to the invention, carried out by the variant of the second embodiment of the setting angle measuring device according to the invention, will now be described.

[0091] At least one blade 22 of the moving wheel 21 comprises a needle 1 IA of type A and a needle 1 IB of type B. In this variant, a needle 1 IA of type A has a first length 11 and a needle of type B has a second length 12 longer than the first length 11, so that a needle 1 IA of type A is only detected by the first row of sensors 12A, and a needle 1 IB of type B is detected by both the first row of magnetic sensors 12A and the second row of magnetic sensors 12B. The reverse configuration, in which a needle 1 IA of type A is only detected by the second row of sensors 12B and a needle 1 IB of type B is detected by both the first row of magnetic sensors 12A and the second row of magnetic sensors 12B, is also possible.The following description will be transposed to this inverse configuration by the inversion of the first row of magnetic sensors and the second row of magnetic sensors.

[0092] If the common setting angle q> to be measured is included in the first angular range [0i; ô], only a needle 1 IA of type A is detected, and only by the first row of magnetic sensors 12A, when the corresponding blade 22 passes through the detection field of the first row of magnetic sensors 12A.

[0093] If the common setting angle q> to be measured is included in the multiple range [ô ;y], a needle 11A of type A is detected by the first row of magnetic sensors 12A; a needle 11B of type B is detected both by the first row of magnetic sensors 12A and by the second row of magnetic sensors 12B when the corresponding blades 22 pass through the respective detection fields thereof.

[0094] If the common setting angle q> to be measured is included in a second angular range [y; 02], only a needle 1 IB of type B is detected, and by the first and second row of magnetic sensors 12A and 12B during the passage of the corresponding blades 22 in their detection field.

[0095] [Fig. 14] is a schematic representation of different types of signals received by the processing unit for different values ​​of the common setting angle q>.

[0096] For each value of the common setting angle q> illustrated, a first signal a and a second signal b are represented. The first signal a corresponds to the signal received by the first row of magnetic sensors 12A. The second signal b corresponds to the signal received by the second row of magnetic sensors 12B.

[0097] When the common setting angle q> to be measured is included in the second angular range [y; 02], illustrated in [Fig. 14] by a value equal to 90 degrees, that is to say that the blades 22 of the moving wheel 21 are in the “flag” position, the needle 11a of type A of a blade 22 comprising a needle 11A of type A and a needle 11B of type B facing the first row of sensors 12A and the second row of sensors 12B is not detected. But the needle 11B of type B is detected by the first row of sensors 12A. Thus, the first module of the processing unit receives the first signal a, which comprises, between two relative reference signals, a primary peak PB1. The second module of the processing unit receives the second signal b. The second signal b comprises, between two relative reference signals, a secondary peak PB2 corresponding to the passage of the needle 1 IB of type B of the blade 22 in the field of the second row of sensors 12B.The time shift, in the first signal a, between the relative reference signal formed by the peaks PRELi and PreL2 and the primary peak PBi, and that, in the second signal b, between the relative reference signal formed by the peaks Preli and PREL2 and the secondary peak PB2j make it possible to calculate the common setting angle q> from geometric and kinematic parameters of the turbomachine 1. .

[0098] When the common setting angle q> to be measured is included in the multiple range [ô ;y], illustrated in [Fig. 14] by values ​​equal to 30 or 40 degrees, the first module of the processing unit receives, between two relative reference signals, a first peak PAb corresponding to the passage in the detection field of the first row of magnetic sensors 12A of the needle 1 IA of type A of the blade 22 facing the first row of magnetic sensors 12A and the second row of magnetic sensors 12B, and a second peak PBb corresponding to the detection of the needle 1 1B of type B of said blade 22. The second module of the processing unit receives, between two relative reference signals, a single peak PB2, corresponding to the passage in the detection field of the second row of sensors 12B of the needle 1 1B of type B of the blade 22.

[0099] When the common setting angle q> to be measured is included in the range [01; y], illustrated in [Fig. 14] by a value equal to 0 degrees, that is to say, the blades 22 of the moving wheel 21 are close to the “reverse” position, the needle 11B of type B of the blade 22 facing the first row of sensors 12A and the second row of sensors 12B is not detected. Thus, the second module of the processing unit receives a second signal b composed solely of the relative reference signals and the absolute reference signal. The first module of the processing unit receives the first signal a. The first signal a comprises, between two relative reference signals, a peak Pai corresponding to the passage of the needle of type A of the current blade. The offset temporal relationship between the relative reference signal formed by the Preli and PreL2 peaks and the PAi peak makes it possible to calculate the common pitch angle q> from geometric and kinematic parameters of the turbomachine.

[0100] This variant of the measuring method according to the invention makes it possible to measure the common setting angle q> over the entire range [0i; 02] on the basis of clearly identified electrical signals.

[0101] Thus, the invention makes it possible to extend the measurement range of the pitch angle of the blades 22 in a variable pitch angle system, by combining magnetic needles. According to the different embodiments of the invention and their variants, it is possible for example to limit the number of needles, to increase the measurement accuracy thanks to a multiplicity of measurements, or to optimize the device according to the invention by limiting its redundancy.

[0102] Alternative embodiments of the invention are possible.

[0103] Thus, in a first variant, the needles 1 IA of type A have a first shape and the needles 1 IB of type B have a second shape different from the first shape. This makes it possible to model the peaks PAi, PA2, corresponding to the detection of the needles 1 IA of type A, and the peaks PBi, Pb2, corresponding to the detection of the needles 1 IB of type B. This modeling facilitates the recognition of these peaks.

[0104] Furthermore, in the various embodiments and variants described, it has been described that the detection of the needles 11A of type A precedes that of the needles 11B of type B. In other words, the needles 11A of type A are the first detected after the detection of a relative reference magnetic target (or of the absolute reference magnetic target). A second variant consists of the inverse configuration, that is to say, in which the needles 11B of type B are the first detected after the detection of a relative reference magnetic target (or of the absolute reference magnetic target) is possible by modifying the geometry of the device.

Claims

Claims

1. Device for measuring the blade pitch angle of a turbomachine with a first axis X, comprising: - a movable wheel (21) centered on the first axis X provided with a plurality of blades (22) arranged radially around the axis X, each blade (22) having a root (22a) at which it is pivotally mounted around a second radial pivot axis Y, - a fixed frame (80) with axis X, comprising at least one set of fixed magnetic sensors (12, 12A, 12B) perpendicular to the first axis X, - the movable wheel (21) comprising a first magnetic target (13), the first magnetic target being fixed on the movable wheel (21), - each blade (22) having a profile oriented along a third axis Z, - a first magnetic needle (1 IA) fixed on a first blade and forming a first angle alpha with the third axis Z of the first blade, - the first magnetic target (13) serving as a reference for the first blade,- characterized in that the measuring device comprises a second magnetic needle (1 IB) fixed on a second blade different from the first blade and forming a second angle beta with the third axis Z of the second blade, the second angle beta being different from the first angle alpha.,

2. Measuring device according to claim 1, characterized in that the second angle beta is between alpha +20 degrees and alpha + 50 degrees.

3. Device according to one of claims 1 or 2, characterized in that the first angle alpha is between 70 and 130 degrees.

4. Measuring device according to one of claims 1 to 3, characterized in that: - the moving wheel (21) comprises a second magnetic target (14) serving as a reference for the second blade, the first blade and the second blade are successive, the at least one set of fixed magnetic sensors consists of a single set of magnetic sensors (12).

5. Method for measuring the pitch angle of a blade of a turbomachine by a measuring device according to claim 4, the measuring device further comprising a processing unit, characterized in that: the process includes: • either a single detection step (Ela), by the single set of magnetic sensors (12), of a single variation in magnetic field, • either a multiple detection step (Elb), by the single set of magnetic sensors (12), of a first variation in magnetic field and a second variation in magnetic field, if the method comprises the single detection step (Ela), the single variation in magnetic field corresponds to the passage of the first magnetic needle (1 IA) or of the second magnetic needle (1 IB) near the single set of sensors, if the method comprises the multiple detection step (Elb) the first variation of magnetic field corresponds to the passage of the first magnetic needle (1 IA) near the single set of sensors (12) and the second variation of magnetic field corresponds to the passage of the second magnetic needle (1 IB) near the single set of sensors (12), the method comprises, following the single detection step (Ela) or the multiple detection step (Elb), a step of calculating the setting angle (E4) by the processing unit on the basis of an electrical signal representative of a variation in magnetic field.

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