Device for measuring pitch angle and associated method for measuring pitch angle

Abstract

One aspect of the invention relates to a device for measuring the pitch angle of blades of a turbine engine with a first axis X, comprising: - a movable wheel which is centred on the first axis X and is provided with a plurality of blades arranged radially about the first axis X, each blade having a root at which it is mounted so as to pivot about a second radial pivoting axis Y, - a fixed frame of axis X, comprising at least one set of fixed magnetic sensors perpendicular to the first axis X, - the movable wheel comprising a first magnetic target, the magnetic target being attached to the movable wheel, each blade having a profile oriented along a third axis Z, - a first magnetic needle attached to 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 attached 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.

Description

DESCRIPTION TITLE: Calibration angle measuring device and associated calibration angle measuring method TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of variable-pitch turbine blades in turbomachinery. The invention finds particular application in the field of aeronautics, especially for turbine blades of jet engines or turboprop aircraft.

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

[0003] Figure 1 represents a turbomachine 1 with a first axis X, comprising, from upstream to downstream, a blower module 2 and a twin-spool gas generator consisting of a first compressor 3, a second compressor 4, a combustion chamber 5, and two series-connected turbines 6 and 7. The blower module 2 is mounted on a fixed frame 80 with a first axis X and consists of a rotating wheel 21 centered on the first axis X. During operation of the turbomachine 1, the rotating wheel rotates about the first axis X. The rotating wheel is equipped with a plurality of blades 22 arranged radially about the first axis X. As illustrated in Figure 2, each blade 22 has a foot 22a at which it is pivotally mounted about a second radial axis Y. Thus, in addition to its rotation around the X axis in a manner fixed with the movable wheel 21, each blade 22 pivots around the second radial pivoting 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 X-axis of the turbomachine 1. As illustrated in Figure 3, the first X-axis of the turbomachine 1 corresponds to the direction of gas flow within the turbomachine, represented by arrow F. When a blade 22 is in the "feathered" position, represented by line Pd, it allows the gases to flow freely and its pitch angle is 90° with respect to a tangent line A. When the blade 22 is in In the "reverse" position, represented by the line Pr, its pitch is reversed, thus reversing the direction of gas flow around the blade 22. The pitch angle is then within an angular range of negative angles, approximately from 0 degrees to -20 degrees. Between these two positions, the blade is in a pitch position Pv, ​​known as the flight pitch. In variable pitch angle systems, measuring the blade pitch angle allows it to be monitored and adjusted accordingly, depending on flight requirements.

[0005] There are devices for measuring blade pitch angle that use ferromagnetic needles 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 foot 22a of a blade 22 whose pitch angle is being measured, passes in front of a fixed sensor 120, which then detects a change in the magnetic field. Analysis of the signal detected by the fixed sensor 120, using reference signals corresponding to the detection of an absolute reference target 13 and relative reference targets 14, allows the blade pitch angle to be determined.

[0006] However, the angular measurement range of this type of device is often limited by the turbomachine's architecture. Indeed, as illustrated in Figure 6, there is a measurement dead angle 0M due to the physical limitations 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 turbomachine components. For example, in Figure 6, the magnetic needle 110 no longer passes within the detection field of the fixed sensor 120 for positions between positions Pd and Pvo of the blade 22, corresponding to the positions of the magnetic needle 110d and 11 Ovo. Typically, the range of pitch angles between 60 and 90 degrees is not measurable.

[0007] Generally, with certain turbofan engine architectures, it is impossible to measure the entire angular range covering the blade pitch angles between the "feathered" and "reverse" positions. However, it is advantageous to measure all blade pitch positions. For example, during turbofan engine startup, the blades are typically in the "feathered" position. However, this position may not be measurable if the corresponding position of the magnetic needle 110 is in a blind spot of the fixed sensor 120. SUMMARY OF THE INVENTION

[0008] The invention offers a solution to the problems mentioned above, by allowing the angle of adjustment measurement range to be broadened, in order to improve the control of this parameter.

[0009] A first aspect of the invention relates to a device for measuring the blade pitch angle of a turbomachine with a first X-axis, comprising: - a movable wheel centered on the first axis X, equipped with a plurality of blades arranged radially around the first axis X, each blade having a foot at the level of which it is mounted to pivot around a second radial axis Y of pivoting, - 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 for measuring blade pitch angles is extended. It is possible to measure pitch angles corresponding to extreme blade pitch positions such as the "flag" position and the "reverse" position, due to the offset between the first and second magnetic needles.

[0011] Advantageously, the second angle beta is between alpha +20 degrees and alpha +50 degrees. Thus, an angular measurement range of up to 110 degrees for the calibration angle 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 the angle of adjustment measurement. Indeed, in the flag position Pd, the angle of adjustment can be equal to 85 or 90 degrees with respect to the tangent line A. In the position In the "reverse" Pr setting, the angle of alignment can be -5 degrees or -15 degrees. This range of values ​​allows the first and second magnetic needles to be positioned so that they can pass within the detection field of magnetic sensors.

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

[0014] In a second embodiment, the first blade and the second blade are coincident and the fixed frame includes a first set and a second set of fixed magnetic sensors perpendicular to the first X axis. This configuration makes it possible to measure the pitch angle of each turbine blade regardless of the pitch angle value within 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 increases the redundancy of the measurement system and improves the accuracy of the calibration angle measurement.

[0016] In a variant of the second embodiment, the first and second magnetic needles have different lengths. This configuration balances the redundancy of the measurement system while maintaining an extended angular measurement range for the calibration angle.

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

[0018] A second aspect of the invention relates to a method for measuring the pitch angle of a turbine blade using the measuring device according to the first embodiment, the measuring device further comprising a processing unit, the method comprising: - either a single detection step (E1 a), by the single set of magnetic sensors, of a single variation in magnetic field, - either a multiple detection step (E1 b), by the single set of magnetic sensors, of a first variation of magnetic field and a second variation of magnetic field, where: - if the process includes the single detection step (E1 a), the single variation in magnetic field corresponds to the passage of the first or second magnetic needle near the single row of sensors, - if the process includes the multiple detection step (E1 b) the first variation of magnetic field corresponds to the passage of the first magnetic needle near the single set of sensors and the second variation of magnetic field corresponds to the passage of the second magnetic needle near the single set of sensors, and where the process includes, following the single detection step (E1 a) or the multiple detection step (E1 b), a step of calculating the calibration angle (E4) by the processing unit on the basis of an electrical signal representative of a variation of magnetic field.

[0019] A third aspect of the invention relates to a method for measuring the pitch angle of a turbine blade using a measuring device according to the second embodiment or a variant thereof, 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 process includes 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 process includes the multiple detection step (E2b) the first variation of magnetic field corresponds to the passage of the first magnetic needle near the first set of sensors and the second variation of magnetic field corresponds to the passage of the second magnetic needle near the second set of sensors, and where the process includes, following the single detection step (E2a) or the multiple detection step (E2b), a step of calculating the calibration angle (E5) by the processing unit on the basis of an electrical signal representative of a variation of 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 illustrative purposes only and are in no way limiting to the invention. - Figure 1 shows a schematic representation of a turbomachine according to the prior art. - Figure 2 shows a variable-pitch turbomachine blade foot according to the prior art. - Figure 3 shows different positioning options for a turbomachine blade. - Figure 4 represents a three-dimensional view of a prior art turbomachine blade pitch angle measuring device. - Figure 5 is a cross-section of the turbine blade pitch angle measuring device of Figure 4. - Figure 6 is an illustration of a measurement blind spot in a prior art turbomachine blade pitch angle measuring device. - Figure 7 represents the direction of a third axis defined by each of the turbomachine blades according to the invention are oriented. - Figure 8a and Figure 8b schematically illustrate the positioning of a first magnetic needle and a second magnetic needle according to the invention. - Figure 9a and Figure 9b represent a device for measuring angle of adjustment according to a first embodiment of the invention. - Figure 10a, Figure 10b, Figure 10c and Figure 10d represent, for different blade pitch angles, a pitch angle measurement device according to a second embodiment of the invention. - Figure 11 a, Figure 11 b, Figure 11 c and Figure 11 d represent, for different blade pitch angles, a pitch angle measurement device according to a variant of the second embodiment of the invention. - Figure 12 schematically represents, for different blade pitch angles, an example of a signal received by a processing unit of the pitch angle measurement device according to the first embodiment of the invention. - Figure 13 schematically represents, for different blade pitch angles, examples of signals received by the processing unit of the pitch angle measurement device according to the second embodiment of the invention. - Figure 14 schematically represents, for different blade pitch angles, examples of signals received by the processing unit of the pitch angle measurement device according to the variant of the second embodiment of the invention. DETAILED DESCRIPTION

[0022] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

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

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

[0025] We consider here a turbomachine 1, of the turbojet type, comprising the components of Figure 1, and in particular the fan module 2 including the impeller 21 and the blades 22. The first compressor 3 is connected by a turbine shaft 71 with axis X to the turbine 7 to form a low-pressure casing. The second compressor 4 is connected by a shaft 61, with axis X, to the turbine 6 to form a high-pressure casing. The fixed structural elements of the turbomachine include an inlet casing 8 located upstream of the gas generator between the fan module 2 and the compressor 3, and the inter-compressor casing 9 between the compressor 3 and the compressor 4. Downstream, the transmission of the engine's forces to the suspension is ensured by an exhaust casing 10. The impeller 21 is integral with a rotor of the compressor 3, which is rotatably mounted in the inlet casing 8.

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

[0027] Magnetic needles 11 are fixed to the feet of at least some of the blades 22 of the rotating wheel 21. In other words, a blade 22 of the rotating wheel 21 has one 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 rotating wheel 21, or by two different blades. There may be magnetic needles 11 on some blades 22 of the rotating wheel 21 or even on all the blades 22 of the rotating wheel 21. The magnetic needles 11 are divided into a first subset comprising at least one magnetic needle 11A, hereafter referred to as needle type A, and a second subset comprising at least one magnetic needle 11B, hereafter referred to as needle type B.

[0028] A processing unit is planned to receive and process electrical signals from magnetic sensors, which will be described later.

[0029] Each type A needle 11A forms a first angle alpha with the third Z-axis of the blade at its base, as shown in Figure 8a. Each type B needle 11B forms a second angle beta with the third Z-axis of the blade at its base, as shown in Figure 8b. The second angle beta differs 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 - 1 - 50 degrees.

[0030] The movable wheel 21 includes a magnetic reference target 13, fixed to the movable wheel 21 and serving as an absolute azimuthal reference frame. The magnetic reference target has a typical shape, for example comprising three prongs, so as to generate an identifiable variation in the magnetic field when it passes in front of the previously mentioned magnetic sensors, which will be described later, as the movable wheel 21 rotates around the X-axis. The magnetic reference target allows, in particular, the counting of the number of revolutions.

[0031] Furthermore, the movable wheel 21 includes relative magnetic targets 14, fixed on the movable wheel 21 and serving as relative azimuth reference points allowing the identification of certain blades 22 of the movable wheel 21 on the received electrical signals. by the processing unit as will be seen later. The relative magnetic targets 14 also have a typical shape, for example including two claws, so as to generate an identifiable magnetic field variation when they pass in front of the previously mentioned magnetic sensors, when the movable wheel 21 rotates around the first X axis.

[0032] In a first embodiment of the blade pitch angle measurement device according to the invention, illustrated in Figures 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 in the array of magnetic sensors 12 all detect the same signal when a magnetic needle 11A, 11B passes through their detection field. This same signal represents the change in magnetic field induced by the magnetic needle 11A, 11B passing through the detection field of the array of magnetic sensors 12. Thus, this plurality of magnetic sensors ensures redundancy of the received signal, as well as its reception in the event, for example, that one sensor in the array of magnetic sensors 12 is defective. The signal received by the array of magnetic sensors 12 is transmitted to the processing unit. Typically, the signal is a peak in electrical voltage. Preferably, the needles 11A, 11B are identical. This configuration eliminates the need for different needle heads.

[0034] In this embodiment, a type A needle 11A is fixed to the foot of at least one blade 22 of the wheel 21, and a type B needle 11B is fixed to the foot 22a of the blade following at least one blade on the wheel 21. Blades carrying type A needles are called type A blades in this embodiment and blades carrying type B needles are called type B blades.

[0035] Figures 9a and 9b show the passage of a type A blade and a type B blade through the detection field of the magnetic sensor row 12. The pitch angle of the type A blade and the pitch angle of the type B blade are identical. For example, in Figure 9a, the needle 11A, fixed to the first blade, can be seen passing through the edge of the detection field of the row. of magnetic sensors 12. Moreover, as can be seen in Figure 9b, due to the offset between the first angle alpha and the second angle beta, the needle 11 B fixed on a successive blade passes in the detection field of the row of magnetic sensors 12 but more in the center of the detection field compared to Figure 9a.

[0036] In a second embodiment of the blade pitch angle measurement device according to the invention illustrated in Figures 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 distinct 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 X-axis. The first row of magnetic sensors 12A and the second row of magnetic sensors 12B are axially offset along the first X-axis. Different blade alignment positions 22 are shown in Figures 10a, 10b, 10c and 10d.

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

[0039] The magnetic sensors in the first row of magnetic sensors 12A shown in Figures 10a, 10b, 10c, and 10d detect a first signal, identical for each sensor, when a magnetic needle 11A, 11B passes through the detection field of the first row of magnetic sensors 12A. This plurality of magnetic sensors ensures redundancy of the received signal, as well as its reception in the event, for example, that a sensor in the first row of magnetic sensors 12A is defective, or that the magnetic needle 11A, 11B is not within the detection field of a sensor. The first signal represents the change 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 a peak in electrical voltage.

[0040] The magnetic sensors in the second row of magnetic sensors 12B in Figures 10a, 10b, 10c, and 10d detect a second signal, identical for each sensor, when a magnetic needle 11A, 11B passes through the detection field of the second row of magnetic sensors 12B. This plurality of magnetic sensors ensures redundancy of the received signal, as well as its reception in the event, for example, that a sensor in the second row of magnetic sensors 12B is defective, or that the magnetic needle 11A, 11B is not within the detection field of a sensor. The second signal represents the change 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 a voltage spike.

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

[0042] In figure 10a, only the needle 11 B passes through the field of the first row of magnetic sensors 12A and through that of the second row of magnetic sensors 12B.

[0043] In Figure 10b, needle 11A and needle 11B 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 figure 10c, only the needle 11 A passes through the field of the first row of magnetic sensors 12A and through that of the second row of magnetic sensors 12B.

[0045] In figure 10d, only needle 11 A passes into the field of the first row of magnetic sensors 12A.

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

[0047] In figure 11 a, only the needle 11 B passes into the field of the second row of magnetic sensors 12B.

[0048] In Figure 11b, needle 11A is not detected. Needle 11B passes through both the detection field of the first row of magnetic sensors 12A and that of the second row of magnetic sensors 12B.

[0049] In figure 11c, the needle 11A does not pass through the field of the second row of magnetic sensors 12B, but through that of the first row of magnetic sensors 12A.

[0050] In figure 11d, only the needle 11 A passes into the field of the first row of magnetic sensors 12A.

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

[0052] We will describe below a method for measuring the blade pitch angle with a variable pitch angle according to the invention. During flight, a modification of the pitch angles of the blades 22 is actuated; all the blades 22 are pivoted around their second radial pivot axis Y by the same angle.

[0053] In operation, the pitch angle of the blades 22 of the blower module 2 varies over an angular range [0i; 62] between the "reverse" position (corresponding to the pitch angle 0i) and the "flag" position (corresponding to the pitch angle 62).

[0054] The angular range [0i; 62] is divided into three sub-ranges: a first angular range [0i; 5] where only a type A needle 11 A is detected; a so-called "multiple range" [5; y] where a type A needle 11 A and a type B needle 11 B are detected. B is detected; and a second angular range [y; 02] where only a type B needle 11 B is detected.

[0055] For example, the range [01;02] is equal to [-20; 90 degrees]. For example, if the first angular range [01;5] is equal to [-20; 30 degrees], the offset between the first angle alpha and the second angle beta can be chosen to be 50 degrees. Thus, the second angular range [5;02] is equal to [40; 90 degrees].

[0056] We denote cp as 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, implemented by the first embodiment of the blade angle measurement device according to the invention, is described below. Two successive blades of the rotating wheel 21 are respectively a type A blade and a type B blade.

[0059] If the common pitch angle cp to be measured is within the first angular range [01; 5], a type A needle 11 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 pitch angle cp to be measured is within the multiple range [5;y], a type A needle 11 A and a type B needle 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 pitch angle cp to be measured is within the second angular range [y; 02], a type B needle 11 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 movable 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 11 A of type A or 11 B of type B which pass in 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 consisting of three successive peaks PABSI, PABS2 and PABSS, due to the three variations in magnetic field 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 consisting of two successive peaks PRELI and PREL2, due to the two variations in magnetic field created successively by the two claws of said secondary target.

[0065] When a running vane 22 including a needle 11A,11B, and in particular its foot 22a, passes in front of the row of sensors 12, two configurations are possible, depending on the value of the common pitch angle cp.

[0066] If the current blade 22 is a type A blade, the processing unit will receive a signal from the magnetic sensor array 12 only if the type A needle 11A attached to the blade's base passes within the detection field of the magnetic sensor array 12. In other words, the processing unit will receive a signal if the common pitch angle cp is either within the first angular range [0i; y] or within the multiple range [5; y]. Otherwise, i.e., if the common pitch angle cp is within 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 type B blade. Thus, during the passage of the successive blade, if the common pitch angle cp is within 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 type B needle 11 B in the detection field of the row of magnetic sensors.

[0068] Figure 12 is a schematic representation of different types of signals received by the processing unit for different values ​​of the common calibration angle cp.

[0069] When the common pitch angle cp to be measured is within the range [Y; 02], illustrated by a value equal to 90 degrees, i.e., when 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 type B needle 11 B. The time lag between the relative reference signal formed by the peaks PRELI and PREL2 and the peak PB allows the common pitch angle cp to be calculated from the 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 outer diameter of the wheel 21, corresponding to the support area of ​​the blade feet 22a, the angle between the reference magnetic target and the secondary target corresponding to the relative reference signal formed by the peaks PRELI and PREL2, the position of the row of magnetic sensors 12 with respect to the foot 22a of the blade 22 passing in its field, and the rotational speed of the wheel 21.

[0071] When the common pitch angle cp to be measured is within the multiple range [5; y], illustrated in Figure 12 by values ​​of 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 of a type A blade through the detection field of sensor array 12, and the second peak PB corresponds to the passage of the type B blade following the type A blade through the detection field of sensor array 12 on the moving wheel 21. The time lag between the first peak and the second peak corresponds to the angular lag between the type A blade and the following type B blade.

[0072] When the common pitch angle cp to be measured is within the range [01; y], illustrated in Figure 12 by a value equal to 0 degrees, i.e., when 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 type A needle 11A. The time shift between the relative reference signal formed by the peaks PRELI and PREL2 and the peak PB allows the common pitch angle cp to be calculated from the geometric and kinematic parameters of the turbomachine 1.

[0073] The position of the relative reference signal formed by the peaks PRELI and PREL2 allows, by counting from the last absolute reference signal formed by the peaks PABSI, PABS2 and PABSS 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 process, carried out by the second embodiment of the blade angle measurement device according to the invention, is described below.

[0075] At least one blade 22 of the rotating wheel 21 has a needle 11 A of type A and a needle 11 B of type B. A needle 11 A of type A and a needle 11 B of type B have the same length.

[0076] If the common pitch angle cp is within the first angular range [0i ; 5], only a type A needle 11 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 pitch angle cp is within the multiple range [5;y], a type A needle 11 A and a type B needle 11 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 pitch angle cp is within the second angular range [y; 02], only a type B needle 11 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] Figure 13 is a schematic representation of different types of signals received by the processing unit for different values ​​of the common calibration angle cp.

[0080] For each value of the common angle setting cp shown, 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 pitch angle cp to be measured is within the second angular range [y; 02], illustrated in Figure 13 by a value equal to 90 degrees, i.e., when the vanes of the moving wheel 21 are in the "flag" position, the first module of the processing unit receives the first signal a, which includes, between two relative reference signals, a primary peak PBI corresponding to the passage of a type B needle 11 B. A second module of the processing unit receives the second signal b, which includes, between two relative reference signals, a secondary peak PB2 corresponding to the passage of the needle 11 B.

[0082] There is a time lag At, illustrated in Figure 13, between the primary peak PBI and the secondary peak PB2. This time lag 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 foot 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 foot 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 the change in magnetic field induced by the passage of the needle 11B through their respective detection fields at the same time.

[0083] The time lag between the relative reference signal formed by the PRELI and PREL2 peaks and the primary peak PBI in the first signal a, and that between the relative reference signal formed by the PRELI and PREL2 peaks and the secondary peak PB2 in the second signal b, allows the common pitch angle cp to be calculated twice from the geometric and kinematic parameters of the turbomachine 1, as in the first embodiment. Thus, the calculation accuracy of the common pitch angle cp is increased.

[0084] When the common calibration angle cp to be measured is within the multiple range [5; y], illustrated in Figure 13 by values ​​of 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 PAI, then a second primary peak PBI. The first primary peak PAI corresponds to the passage of the type A needle 11 A of the blade 22, facing the first row of sensors 12A, through the detection field of the first row of sensors 12A. The second peak The primary PBI corresponds to the passage of the type B needle 11 B of said blade 22 through the detection field of the first row of sensors 12A. The time shift between the first PAI peak and the second PBI peak corresponds to the angular shift between the type A needle 11 A and the type B needle 11 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 secondary peak PA2, followed by a second secondary peak PB2. The first secondary peak PA2 corresponds to the passage of the type A needle 11 A of the blade 22 through the detection field of the second row of sensors 12B when it is facing the second row of sensors 12B. The second secondary peak PB2 corresponds to the passage of the type B needle 11 B of said blade through the detection field of the second row of sensors 12B. The time lag between the first peak PA2 and the second peak PB2 corresponds to the angular lag between the type A needle 11 A and the type B needle 1 B of the blade.

[0086] This yields four measurements of the common pitch angle cp: two measurements from the detection of the magnetic field variation induced by the type A needle 11A of a current blade 22, by the first row of magnetic sensors 12A and the second row of magnetic sensors 12B respectively, and two measurements from the detection of the magnetic field variation induced by the type B needle 11B of said current blade 22, by the first row of magnetic sensors 12A and the second row of magnetic sensors 12B respectively. Thus, the calculation accuracy of the common pitch angle cp is increased.

[0087] When the common pitch angle cp to be measured is within the first angular range [0i; y], illustrated in Figure 13 by a value of 0 degrees, i.e., when the vanes 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 type A needle 11 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 11 A.

[0088] The time lag observed in Figure 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 foot 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 foot 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 11A through their respective detection fields.

[0089] The time lag between the relative reference signal formed by the peaks PRELI and PREL2 and the primary solid line peak PAI 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, allows the common pitch angle cp to be calculated twice from the geometric and kinematic parameters of the turbomachine 1. Thus, the accuracy of calculating the common pitch angle cp is increased.

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

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

[0092] If the common calibration angle cp to be measured is within the first angular range [0i; 5], only a type A needle 11 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 pitch angle cp to be measured is within the multiple range [5;Y], a needle 11 A of type A is detected by the first row of magnetic sensors 12A; a needle 11 B of type B is detected by both the first row of magnetic sensors 12A and the second row of magnetic sensors 12B when the corresponding blades 22 pass through their respective detection fields.

[0094] If the common pitch angle cp to be measured is within a second angular range [y; 02], only a type B needle 11 B is detected, and by the first and second row of magnetic sensors 12A at 12B when the corresponding blade 22 passes through their detection field.

[0095] Figure 14 is a schematic representation of different types of signals received by the processing unit for different values ​​of the common calibration angle cp.

[0096] For each value of the common calibration angle cp shown, 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 pitch angle cp to be measured is within the second angular range [y; 02], illustrated in Figure 14 by a value of 90 degrees, i.e., when the vanes 22 of the moving wheel 21 are in the "flag" position, the type A needle 11a of a vane 22 comprising a type A needle 11A and a type B needle 11B facing the first row of sensors 12A and the second row of sensors 12B is not detected. However, the type B needle 11B is detected by the first row of sensors 12A. Thus, the first module of the processing unit receives the first signal a, which includes, between two relative reference signals, a primary peak PBI. 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 type B needle 11 B of the blade 22 into 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 PB2, allows the calculation of the common pitch angle cp from geometric and kinematic parameters of the turbomachine 1.

[0098] When the common alignment angle cp to be measured is within the multiple range [5; y], illustrated in Figure 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 PAI, corresponding to the passage through the detection field of the first row of magnetic sensors 12A of the type A needle 11 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 PBI, corresponding to the detection of the type B needle 11 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 through the detection field of the second row of sensors 12B of the type B needle 11 B of the blade 22.

[0099] When the common pitch angle cp to be measured is within the range [01; y], illustrated in Figure 14 by a value of 0 degrees, i.e., when the blades 22 of the rotating wheel 21 are close to the "reverse" position, the type B needle 11B 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 includes, between two relative reference signals, a PAI peak corresponding to the passage of the type A needle of the current blade. The time lag between the relative reference signal formed by the PRELI and PREL2 peaks and the PAI peak allows the common pitch angle cp to be calculated from the geometric and kinematic parameters of the turbomachine.

[0100] This variant of the measurement method according to the invention makes it possible to measure the common calibration angle cp over the entire range [01; 02] on the basis of clearly identified electrical signals.

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

[0102] Various embodiments of the invention are possible.

[0103] Thus, in a first variant, type A 11A needles exhibit one shape, and type B 11B needles exhibit a second shape different from the first. This allows for the modeling of the PAI and PA2 peaks, corresponding to the detection of type A 11A needles, and the PBI and PB2 peaks, corresponding to the detection of type B 11B needles. This modeling facilitates the recognition of these peaks.

[0104] Furthermore, in the various embodiments and variants described, it has been stated that the detection of type A needles 11A precedes that of type B needles 11B. In other words, type A needles 11A are the first to be detected after the detection of a relative reference magnetic target (or the absolute reference magnetic target). A second variant consists of the reverse configuration, i.e., in which type B needles 11B are the first to be detected after the detection of a relative reference magnetic target (or the absolute reference magnetic target), which 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 X axis, comprising: - a mobile 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 an X axis, comprising at least one set of fixed magnetic sensors (12, 12A, 12B) perpendicular to the first X axis, - the moving wheel (21) comprising a first magnetic target (13), the first magnetic target being fixed on the moving wheel (21), - each blade (22) having a profile oriented along a third axis Z, - a first magnetic needle (11 A) 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 (11 B) 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 dawn and the second dawn 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 method comprises: o either a single detection step (E1 a), by the single set of magnetic sensors (12), of a single variation in magnetic field, o or a multiple detection step (E1 b), 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 (E1 a), the single variation in magnetic field corresponds to the passage of the first magnetic needle (11 A) or the second magnetic needle (11 B) near the single set of sensors, - if the method comprises the multiple detection step (E1 b) the first variation in magnetic field corresponds to the passage of the first magnetic needle (11 A) near the single set of sensors (12) and the second variation in magnetic field corresponds to the passage of the second magnetic needle (11 B) near the single set of sensors - the method comprises, following the single detection step (E1 a) or the multiple detection step (E1 b), a step of calculating the setting angle (E4) by the processing unit on the basis of an electrical signal representative of a variation in the magnetic field.

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