Aircraft turbine engine having means for detecting the axial displacement of a fan

Abstract

The invention relates to an aircraft turbine engine comprising: a fan (12) capable of rotating about a longitudinal axis and comprising a rotor disc (30) and variable angular pitch blades (32) mounted at the periphery of the disc, and a system (50) for determining an angular pitch position of a blade comprising: - a plurality of pitch reference members (52) rigidly attached to the disc, - a position reference element (58) rigidly attached to the blade and capable of changing angular position relative to the member in the event of a change in the angular pitch of the blade, - a sensor (62) fixed relative to the fan and capable of determining a relative angular position between the element and the member by detecting the course of the element and the member during the rotation of the fan. The turbine engine is configured to detect an axial displacement of the fan by detecting an axial displacement of the member from the sensor.

Description

DESCRIPTION TITLE: AIRCRAFT TURBOMACHINE WITH DETECTION OF AXIAL DISPLACEMENT OF A FAN Technical field

[0001] This disclosure relates to an aircraft turbomachine with axial displacement detection of a fan and a method for detecting axial displacement of a fan of an aircraft turbomachine. Prior art

[0002] It is known in aircraft turbomachines with ducted or unducted fans to manage the situation in which a mechanical break occurs in the mechanical assembly connecting the fan to the rest of the engine and which leads to the release of the fan.

[0003] Engine manufacturers have come up with several solutions to avoid such an event: - the integration of blower retention systems involving mechanical stops; - the addition of sensors which break like mechanical fuses in the event of axial movement of the fan; - the installation of a double skin on mechanical elements in order to be able to rely on another mechanical force path to retain the fan. Statement of the invention

[0004] Although these systems prove satisfactory, there is nevertheless a need to detect axial displacement of the fan in a simple manner.

[0005] The invention thus relates to an aircraft turbomachine comprising: a fan which is capable of rotating around a longitudinal axis XX' and which comprises a rotor disk and a plurality of blades with variable angular pitch mounted on the periphery of the disk, a system for determining an angular pitch position of at least one dawn including: - several timing reference organs which are integral with the rotor disc, - a position reference element secured to said at least one blade and which is capable of changing its angular position relative to the setting reference members in the event of a modification of the angular setting of said at least one blade, -at least one sensor which is positioned in a fixed manner relative to the fan and which is capable of determining a relative angular position between the position reference element and the timing reference members by detecting the passage of the position reference element and the timing reference members during rotation of the fan, characterized in that the turbomachine is configured to detect an axial displacement of the fan by detecting an axial displacement of the timing reference members from said at least one sensor.

[0006] The use of at least some of the components (setting reference members (targets or claws and sensor(s)) of the system for determining an angular setting position of the blade of the turbomachine makes it possible to simply detect an axial displacement of several setting reference members, and therefore an axial displacement of the fan, since the members are integral with the disk which moves axially with the fan. The use of these existing components, even if they can be somewhat modified structurally depending on the case, makes it possible not to have to add dedicated components (in particular one or more sensors), which simplifies the configuration of the turbomachine, its assembly and its maintenance and does not increase the on-board weight or the size.Furthermore, by using one or more existing sensors the electronics are simplified since functionality is added without increasing the number of inputs and outputs of the electronic computer or processing unit.

[0007] According to other possible characteristics, taken alone or in combination: - the turbomachine comprises a processing unit which is configured to carry out processing on at least one signal produced by said at least one sensor in order to detect an axial displacement of the timing reference members; - the processing comprises a comparison between said at least one signal produced by said at least one sensor and at least one reference signal representative of an unshifted axial position of the timing reference members and a detection of an axial displacement of the timing reference members in the event of determination of a difference with said at least one reference signal; -the processing comprises an analysis of said at least one signal produced by said at least one sensor and comprising several successive signal portions, and a detection of an axial displacement of the timing reference members in the event of detection, in said at least one signal thus analyzed, of a signal portion having a shorter period or a lower amplitude than that of the other signal portions of said at least one analyzed signal; -at least one timing reference member has a generally elongated shape along the longitudinal axis and extends from a first end to a second opposite end which is closer to said at least one sensor than the first end and which has a reduced width compared to the first end; -at least one timing reference member has a generally elongated shape along the longitudinal axis and extends from a first end to a second opposite end which is closer to said at least one sensor than the first end and which has a reduced thickness compared to the first end; - the timing reference organs are distributed along a circumference of the rotor disc; - the timing reference members are distributed either according to a group of timing reference members or according to several groups of timing reference members distributed along a circumference of the rotor disk; - at least some of the groups of timing reference members each comprise at least two or three successive timing reference members; -the turbomachine is configured to confirm detection of axial displacement, either by detecting the axial displacement at least twice from the same group of timing reference members, or by detecting the axial displacement at least twice from at least two different groups of timing reference members; - the turbomachine comprises a system for controlling the operation of the turbomachine which is configured to stop the operation of the turbomachine in the event of detection of an axial displacement of the fan; - said at least one sensor is chosen from a variable reluctance sensor, a capacitive sensor, an inductive sensor, an optical sensor; -said at least one sensor comprises a plurality of sensors; - the turbomachine is also configured to determine a rotation speed of the fan from said at least one sensor; - the turbomachine comprises a reduction gearbox to which the fan is connected; - the turbomachine has an axial mechanical stop acting as an axial restraint for the fan in the event of axial displacement of the latter.

[0008] The invention also relates to a method for detecting an axial displacement of a turbomachine fan which is capable of rotating around a longitudinal axis XX' and which comprises a rotor disk and a plurality of variable angular pitch blades mounted on the periphery of the disk, the detection method comprising the use, on the one hand, of several pitch reference members secured to the rotor disk and of at least one sensor positioned in a fixed manner relative to the fan and on the path of the pitch reference members during rotation of the fan, to detect an axial displacement of the fan from the detection of an axial displacement of the pitch reference members, the pitch reference members and said at least one sensor being used for determining an angular pitch position of at least one blade.

[0009] The above process provides the same advantages as those of the turbomachine briefly discussed above and they will therefore not be repeated. Brief description of the drawings

[0010] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.

[0011] [Fig. 1] Figure 1 is a general schematic view in axial section of an aircraft turbomachine according to one embodiment of the invention;

[0012] [Fig. 2] Figure 2 is an enlarged schematic general view in axial half-section of a part of the turbomachine shown in Figure 1 according to a possible configuration;

[0013] [Fig. 3] Figure 3 is a schematic general perspective view showing the location of various components relative to the fan blades;

[0014] [Fig. 4] Figure 4 is a partial schematic top view of some of the components illustrated in Figure 3;

[0015] [Fig. 5] Figure 5 is a partial schematic perspective view of the components illustrated in Figure 4;

[0016] [Fig. 6] Figure 6 is a schematic view showing an example of a succession of signals detected by a sensor such as those shown in Figures 3 to 5;

[0017] [Fig. 7] Figure 7 is a schematic view showing a signal detected by a sensor at the input of a threshold comparator;

[0018] [Fig. 8] Figure 8 is a schematic view showing the signal of Figure 7 at the output of the comparator;

[0019] [Fig. 9] Figure 9 is a schematic view showing different functional components of the information processing chain coming from the sensors;

[0020] [Fig. 10] Figure 10 is a schematic perspective view of a group formed of three angular setting reference members according to an exemplary embodiment;

[0021] [Fig. 11] Figure 11 is a schematic view similar to that of Figure 4 after axial displacement of the fan;

[0022] [Fig. 12] Figure 12 is a schematic view showing both a signal detected by a sensor at the input of a threshold comparator and the signal at the output of this comparator with a difference between the periods of the successive signal portions;

[0023] [Fig. 13A] Figure 13A is a schematic side elevation view of an angular setting reference member according to another exemplary embodiment;

[0024] [Fig. 13B] Figure 13B is a schematic perspective view of a group formed of three angular setting reference members according to an exemplary embodiment;

[0025] [Fig. 14] Figure 14 is a schematic view of a signal detected by a sensor showing a difference in amplitude between successive signal portions. Detailed description

[0026] Figure 1 schematically illustrates along a longitudinal section an aircraft turbomachine 10 such as a dual-flow turbojet according to one embodiment of the invention. Other types of turbomachines can alternatively be envisaged.

[0027] The turbomachine 10 here comprises, from upstream to downstream depending on the circulation of the air flow, a ducted fan 12, a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20 and a low-pressure turbine 22. All these elements exert their action in a known manner on a first annular air flow circulating in a first central duct 24 coaxial with the axis XX'. A second annular bypass duct 26 concentrically surrounds the first central duct for the flow of a second annular air flow. Other turbojet configurations can alternatively be envisaged with a single compressor and a single turbine, or even with more than two compressors and more than two turbines, or even with an unducted propeller.

[0028] The fan 12 which is capable of rotating about a longitudinal axis XX' comprises a rotor disk 30 and a plurality of blades 32 with variable angular pitch which are each mounted in a known manner on an outer periphery of the disk, along a circumference thereof. Each blade 32 extends away from the outer periphery of the disk 30 in a radial direction relative to the longitudinal axis XX'. Each blade 32 also extends in the axial direction and has a suitable aerodynamic profile.

[0029] The rotor disk 30 is connected here to the low pressure shaft of the turbomachine, either directly or via a reduction gear box. The disk forms part of a central structure of the engine of the turbomachine 10.

[0030] Figure 2 also illustrates schematically (along an axial half-section), in an enlarged and partial form of the turbomachine of Figure 1, the main elements which can be involved in the mechanical assembly connecting the fan 12 to a reduction gear box of the turbojet in an exemplary embodiment (it should be noted that this is only one possible fan mounting configuration and that others are of course conceivable). The disk 30 of the fan 12 can thus be mounted on a shaft 34 extending downstream in the form of an engagement part 36 which is mechanically meshed with the reduction gearbox 38. The reduction gearbox 38 may comprise, in this exemplary embodiment, a planet carrier 38a inside which are arranged satellites, one 38b of which is shown, and a sun 38c. The sun 38c, for its part, is connected to the shaft of the downstream low-pressure compressor 14 not shown here.

[0031] A support part 40 is mounted concentrically on the external surface of the shaft 34 (on a portion of the shaft with an enlarged diameter), between the upstream portion of the shaft connected to the disc 30 and the downstream engagement portion 36. A ferrule 42 is mounted by an internal periphery 42a on the support part 40 and by an external periphery 42b on an axial stop 44, only a portion of which is shown here. The axial stop 44 serves as a stop in the event of unwanted axial movement of the fan. In Figure 2, the zones Z1 and Z2 represent the zones of fragility where the mechanical connections are likely to break in the event of unwanted axial movement of the fan. This is the case at the level of the axial thrust bearing 44 and also at the level of the connection between the shaft 34 and the downstream engagement part 36 (zone Z2) because the box 38 is not designed to take up axial forces.Alternatively, a break can occur downstream, inside box 38.

[0032] A known mechanism for changing the angular position of the blades (not shown) is integrated into the turbomachine in order to orient each blade, around its radial extension direction, according to the angular setting requirements for the operation of the fan. The mechanism generally acts on the supports of the blade roots and orients them appropriately, from the inside of the rotor disc.

[0033] Figure 3 is a partial schematic perspective view of the fan 12 equipped with the blades 32 partially shown and in front of which is mounted a part 48 integral in rotation with the rotor disk 30 of the fan. The part 48 here takes the form of a ferrule or a disk whose external peripheral edge is folded so as to form a substantially cylindrical edge of revolution around the longitudinal axis XX'. The part 48 could however take other alternative forms not shown here. A system 50 for determining an angular setting position of the blades is mounted in relation to the fan 12 and comprises several components integrated into the turbomachine and at least some of which are used to detect an axial displacement (change in axial position) of the fan.

[0034] This system 50 generally comprises several timing reference members (targets or claws) 52 which are integral with the rotor disk 30, via the shroud 48, and therefore which rotate with the latter during rotation of the fan. In the present example, the timing reference members 52 are for example grouped in the form of several groups or sets of several members 52 each (at least two groups or sets) which are distributed along a circumference of the shroud. By way of example, there are two groups G1, G2 of two members 52 each, arranged diametrically opposite on the shroud, and a group G3 of three members 52 arranged in an angular orientation of 90° relative to each of the two groups G1, G2.Although the system here comprises more than two members 52, it will be noted that only two members 52 are sufficient from a functional point of view to determine an axial displacement of the fan.

[0035] In the present example, in each grouping the reference wedging members 52 are spaced laterally from each other in a direction which corresponds to a circumferential direction of the ferrule and they are joined at a common base, thus forming a sort of rake or fork. Other ways of constituting a grouping of members 52 can be used alternatively.

[0036] Figure 4 illustrates in top view the installation of the group G3 (without the ferrule 48) and, above, the installation of several blade mounting openings 54 (the blades are not shown here) located at the external periphery of the rotor disk 30. In each opening 54, a blade support 56 is seen intended to receive the root of the corresponding blade. In this example, each member 52 has a generally elongated shape along the longitudinal axis and extends, tapering from a first end 52a located at the base of the group to a second free opposite end 52b located away from the base.

[0037] This system 50 also generally comprises a position reference element 58, called a needle, secured to a blade and which is positioned as it would be in the presence of the blade. The needle 58 has a generally elongated shape which extends, from a widened base fixed for example to the blade support, away from the blade (alternatively, the needle can be fixed to the blade). As shown in FIG. 4, this needle 58 is not aligned along the axis XX' but forms with it an angular gap which reflects the fact that the angular orientation (setting) of the blade is likely to vary during operation of the fan. Thus, the needle 58 is able to change its angular position relative to the setting reference members 52 in the event of a controlled modification of the angular setting of the blade by the mechanism briefly described above.The angular orientation of the needle visible in Figure 3 is therefore likely to vary over time and may either move closer to or further away from the timing reference members 52. It will be noted that from a functional point of view a needle is not necessary to determine an axial displacement of the fan as described in this document.

[0038] Returning to Figure 3, several through openings 60 are arranged in the thickness of the shell and distributed circumferentially thereon in order to allow the needles 58 mounted on the blades to extend through these openings. The angular extent of each opening 60 is dimensioned to cover the entire angular excursion range of the needle concerned. As can be seen in Figure 3, only certain blades 32 are equipped with a needle. In the example considered, only four blades are concerned and the shell 48 therefore has four openings 60.

[0039] This system 50 also generally comprises at least one sensor 62 which is positioned in a fixed manner relative to the fan. Here, said at least one sensor 62 is fixed to a stator-forming part of the turbomachine. In the illustrated example, several sensors 62 are used, for example four in number.

[0040] In Figure 3 the sensors 62 are mounted on a sensor support 64 which, in Figure 4, is mechanically secured to the stator part 66 partially shown. Other mountings of the sensor(s) can alternatively be envisaged.

[0041] Figure 5 is a partial enlarged rear perspective view of the arrangement of Figure 4 and showing the relative arrangement of the sensors 62, the needle 58 and the timing reference members 52.

[0042] Generally, the sensor(s) 62 are capable of determining the relative angular position between the needle 58 and the timing reference members 52 by detecting the passage of the needle and the timing reference members during rotation of the fan. The use of two timing reference members 52 makes it possible to differentiate such a member from a needle with respect to a sensor 62. Each sensor 62 provides a signal which is processed in an appropriate and known manner by an electronic processing unit.

[0043] Figure 6 schematically represents a succession of signals produced by the detection, by a sensor, of the passage of the different groups of timing reference members 52 and the needles 58. Thus, for the group G3 of three members 52 the signal is similar to a sinusoid with three periods, while for the groups G1 and G2 of two members 52, the signal is similar to a pseudo sinusoid with two periods and for the needles the signal is similar to a pseudo sinusoid with a single period.

[0044] The electronic processing unit can carry out, beforehand, formatting operations (filtering, comparison with a threshold, etc.).

[0045] Figure 7 illustrates a sinusoidal signal with three periods which is injected at the input of a threshold comparator and Figure 8 illustrates the signal at the output of the comparator.

[0046] This is how an angular setting position of the blades is determined and also how the rotation speed of the fan can be determined (on the rising edges of the digital signals: measurement of the frequency of the signals generated by the sensors, sampling and conversion law, etc.).

[0047] By way of example, the sensor(s) 62 are chosen from a variable reluctance sensor, a capacitive sensor, an optical sensor, etc. in the embodiments described here, the sensor or each sensor is, for example, a variable reluctance sensor.

[0048] In the event of axial displacement of the fan towards the front of the turbomachine (along arrow D in figure 4), the signal produced by the sensor 62 (if there is only one) or by each of the sensors 62 is modified by relative to a signal produced when the blower has not changed axial position. Such a signal can be referred to as a reference signal which is representative of an unshifted axial position.

[0049] According to a first embodiment, the axial offset of the fan is such that the timing reference members 52 are axially moved back by a distance such that they no longer pass under the sensor(s) during rotation of the fan and the latter therefore no longer detect the passage of the members. This situation thus results in a loss of signal (loss of angular timing information). For this purpose, the members 52 have a calibrated length, that is to say a length which is dimensioned to detect an axial displacement of a determined amplitude.

[0050] The turbomachine 10 comprises, as schematically represented in FIG. 9, in addition to the electronic processing unit UT, a system SC for controlling the operation of the turbomachine which is configured to stop the operation of the turbomachine, for example by cutting off the fuel supply, in the event of detection of an axial displacement of the fan.

[0051] In the present example, when the signal is thus lost by the sensor(s) 62, the information relating to a loss of information from this or these sensors 62 is transmitted by the electronic processing unit UT to the control system SC for the operation of the turbomachine which commands the stopping of the fuel supply to the engine. For example, the system SC sends a command to the fuel supply system SA or, more particularly, to a supply valve in order to close it.

[0052] It should be noted that before deciding to stop the operation of the turbomachine it is preferable to confirm the detection of the axial displacement of the fan. This can be achieved by carrying out several detections which all produce the same result. For example, this confirmation can take place by detecting at least twice in succession the loss of signal during the passage of the same members 52 of the same group or by detecting a loss of signal during the passage of several members belonging to different groups which are not necessarily successive. In practice, the detection of loss of signal (which leads to the action of cutting the engine) results in the observation of an absence of signal for a predetermined duration.

[0053] According to a second embodiment, the axial offset of the fan may be of a lesser amplitude than that of the first mode, for example in the case where the axial stop is close to the fan. In such a case, despite their recoil, the timing reference members 52 remain detectable by the sensor(s) during rotation of the fan.

[0054] As shown in Figure 10, at least one of the members 52 may have a free end 52b (end located near the sensor(s)) which is refined or thinned relative to the opposite end 52a connected to the base of the group G3 in this example. The thinning is carried out along the width I of the member(s) 52 and applies in this figure to all the members of the group. It will be noted that this description also applies to a group consisting of two members 52.

[0055] Figure 11 illustrates an offset axial position of the fan relative to the position of Figure 4. The horizontal line referenced L represents the axial position which can be detected by the sensor(s) 62 and it can be seen that in Figure 11 the refined ends 52b of the members 52 are superimposed with this line.

[0056] As mentioned above, the signal produced by a sensor 62, or by each sensor 62 when there are several, comprises a succession of two signal portions which can be similar to sinusoids or pseudo sinusoids.

[0057] In the second embodiment, the detection of axial displacement of the fan can be carried out from a grouping of three members 52 of which only the middle member 52 has its free end 52b refined (unlike in FIG. 10). This arrangement makes it possible to detect in the signal from the sensor(s) a difference between the signal portion corresponding to the middle member 52 of the grouping and the two signal portions framing the two end members 52 whose free end is not refined. It will be noted that the detection can be carried out using several groups of timing reference members.

[0058] Figure 12 represents the shape of the signal produced by a sensor which sees the group of members 52 pass through, of which only the middle member has its end refined, the two end members retaining a nominal width at their free end. In this figure, both the signal SI at the input of the comparator and the signal S2 in the form of square waves at the output are represented. of the comparator. The signal processing carried out by the processing unit UT on the signal S2 of figure 12 makes it possible to identify, among the successive periods Pl, P2 and P3 of the three successive signal portions, the period P2 which is the shortest, this being due to the smaller width of the free end of the middle member 52. The detection of the period P2 in the signal coming from the sensor, or from each sensor if there are several, makes it possible to detect an axial displacement of the fan.

[0059] As for the first embodiment, before stopping the operation of the turbomachine, this axial displacement information is confirmed by carrying out a similar detection with other groups of members 52. Alternatively, the information can be confirmed over several successive detections (for example two or three) or over a complete revolution of the disk.

[0060] In the case where the detection of axial displacement of the fan is carried out from the signal(s) produced by detecting the passage of a group of two members 52, only one of the two members can have a refined end. Thus, the analysis of the resulting signal will result in the determination of two different successive periods for the group, which will make it possible to conclude that there is axial displacement of the fan.

[0061] Alternatively, as already mentioned, the detection of axial displacement can be carried out with all the reference timing members 52 of the same grouping (or of several groups each of two, three or more members 52) having a refined free end. When processing the signal produced by detecting the passage of such a grouping, the unit UT compares this signal with a reference signal recorded in the memory of the unit or of a memory associated with the unit. The reference signal has been previously obtained from a grouping of members (or of several groups) all having the same nominal width from one end to the other.

[0062] It should be noted that to measure the speed of the blower, we carry out processing on the signal illustrated in figure 12, by arming the trigger when the signal passes a certain positive threshold, by taking a time reference when the signal passes from 10 to zero volts with an armed trigger and by calculating the period of the signal as being the duration between two time references.

[0063] A third embodiment will now be described. According to this embodiment, at least one timing reference member 52' ​​is structurally modified so that the signal produced when detecting the passage of the member in front of the sensor(s) is representative of this modification.

[0064] As shown in Figure 13A, the member 52' ​​has a free end 52b' (the one located closest to the sensor(s)) whose thickness is reduced compared to the nominal thickness e of the member. Figure 13B shows a grouping G3' of three members 52' which all have a free end 52b' of reduced thickness. It will be noted that the transverse or lateral gap between two consecutive members or claws 52' is determined as a function of the angular setting range in order in particular not to confuse the detection of a grouping of three members with a grouping of two members followed by a needle. This remark also applies to the other embodiments described previously.

[0065] In this third embodiment, the detection of axial displacement of the fan can be carried out from a grouping of three members 52' of which only the middle member 52' ​​has its free end 52b' of reduced thickness (unlike in FIG. 13B). This arrangement makes it possible to detect in the signal from the sensor(s) a difference between the signal portion corresponding to the middle member 52' ​​of the grouping and the two signal portions corresponding to the two end members 52' (free end with constant nominal thickness) framing the middle member 52'.

[0066] Figure 14 represents the shape of the signal produced by a sensor which sees the group of members 52' pass through, of which only the middle member has its end of reduced thickness, the two end members retaining at their free end a nominal thickness e. This figure represents the output signal of a sensor. The signal processing carried out by the processing unit UT on the signal of Figure 14 makes it possible to identify, among the three successive signal portions constituting the signal, the portion whose amplitude is the lowest (this is the second signal portion framed by the two signal portions corresponding to the two end members 52' whose thickness is nominal). This is due to the reduced thickness of the free end of the middle member 52' ​​which induces an increase in the air gap between the member 52' ​​and the or each sensor. The detection of the amplitude lower A2 compared to the two amplitudes Al and A3 in the signal from the sensor, or from each sensor if there are several, makes it possible to detect an axial displacement of the fan.

[0067] As for the first two embodiments, before stopping the operation of the turbomachine, this information is confirmed for example by carrying out a similar detection with other groups of members 52'. Alternatively, the information can be confirmed on several successive detections (for example two or three) or on a complete revolution of the disk.

[0068] As for the second embodiment, in the case where the detection of axial displacement of the fan is carried out from the signal(s) produced by detecting the passage of a group of two members 52', only one of the two members can have a refined end. Thus, the analysis of the resulting signal will result in the determination of two different successive amplitudes for the group, which will make it possible to conclude that there is axial displacement of the fan.

[0069] Alternatively, as already mentioned, the detection of axial displacement can be carried out with all the reference timing members 52' of the same grouping (or of several groups each of two, three or more members 52') having a free end of reduced thickness. When processing the signal produced by detecting the passage of such a grouping, the unit UT compares this signal with a reference signal recorded in the memory of the unit or of a memory associated with the unit. The reference signal has been previously obtained from a grouping of members all having the same nominal thickness from one end to the other.

[0070] The electronic processing unit or electronic calculator UT of the turbomachine is configured to implement a method for detecting an axial displacement of the fan according to one or more embodiments of the invention. Such a method notably comprises steps of detecting a signal by one or more sensors during the passage of several angular setting reference members (possibly grouped into one or more groups), then processing this signal, possibly by comparison with at least one reference signal representative of a position non-offset axial of the fan, in order to detect an axial displacement of several angular timing reference members.

[0071] The present invention is equally applicable to a turbomachine equipped with a reduction gearbox as to a turbomachine which is not equipped with one.

[0072] Although the present description refers to specific exemplary embodiments, modifications may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

CLAIMS

1. Aircraft turbomachine comprising: a fan (12) which is capable of rotating around a longitudinal axis (XX') and which comprises a rotor disk (30) and a plurality of blades (32) with variable angular pitch mounted on the periphery of the disk, a system (50) for determining an angular pitch position of at least one blade comprising: - several timing reference members (52; 52') which are integral with the rotor disk, - a position reference element (58) secured to said at least one blade (32) and which is capable of changing angular position relative to the setting reference members (52; 52') in the event of modification of the angular setting of said at least one blade, -at least one sensor (62) which is positioned in a fixed manner relative to the fan (12) and which is capable of determining a relative angular position between the position reference element (58) and the timing reference members (52; 52') by detecting the passage of the position reference element and the timing reference members during rotation of the fan, characterized in that the turbomachine is configured to detect an axial displacement of the fan by detecting an axial displacement of the timing reference members (52; 52') from said at least one sensor (62).

2. Turbomachine according to claim 1, characterized in that the turbomachine comprises a processing unit (UT) which is configured to carry out processing on at least one signal produced by said at least one sensor in order to detect an axial displacement of the timing reference members (52; 52').

3. Turbomachine according to claim 2, characterized in that the processing comprises a comparison between said at least one signal produced by said at least one sensor (62) and at least one reference signal representative of an unshifted axial position of the timing reference members (52; 52') and a detection of an axial displacement of the timing reference members (52; 52') in the event of determination of a difference with said at least one reference signal.

4. Turbomachine according to claim 2, characterized in that the processing comprises an analysis of said at least one signal produced by said at least one sensor (62) and comprising several successive signal portions, and a detection of an axial displacement of the timing reference members (52; 52') in the event of detection, in said at least one signal thus analyzed, of a signal portion having a shorter period or a lower amplitude than that of the other signal portions of said at least one analyzed signal.

5. Turbomachine according to one of claims 1 to 4, characterized in that at least one timing reference member (52; 52') has a generally elongated shape along the longitudinal axis and extends from a first end (52a) to a second opposite end (52b) which is closer to said at least one sensor (62) than the first end and which has a reduced width compared to the first end.

6. Turbomachine according to one of claims 1 to 4, characterized in that at least one timing reference member (52; 52') has a generally elongated shape along the longitudinal axis and extends from a first end (5239 to a second opposite end (52b 7 ) which is closer to said at least one sensor (62) than the first end and which has a reduced thickness compared to the first end.

7. Turbomachine according to one of claims 1 to 6, characterized in that the timing reference members (52; 529) are distributed along a circumference of the rotor disc.

8. Turbomachine according to the preceding claim, characterized in that the timing reference members (52; 529) are distributed either according to a grouping of timing reference members (52; 529) or according to several groups of timing reference members (52; 52') distributed along a circumference of the rotor disk.

9. Turbomachine according to the preceding claim, characterized in that at least some of the groups of timing reference members each comprise at least two or three successive timing reference members (52; 52').

10. Turbomachine according to claim 8 or 9, characterized in that the turbomachine is configured to confirm a detection of axial displacement, either by detecting at least twice the axial displacement at from the same group of timing reference members (52; 52'), or by detecting at least twice the axial displacement from at least two different groups of timing reference members (52; 52').

11. Turbomachine according to one of claims 1 to 10, characterized in that it comprises a system for controlling the operation of the turbomachine which is configured to stop the operation of the turbomachine in the event of detection of an axial displacement of the fan.

12. Turbomachine according to one of claims 1 to 11, characterized in that said at least one sensor (62) is chosen from a variable reluctance sensor, a capacitive sensor, an inductive sensor, an optical sensor.

13. Turbomachine according to one of claims 1 to 12, characterized in that the turbomachine is also configured to determine a rotation speed of the fan (12) from said at least one sensor (62).

14. Turbomachine according to one of claims 1 to 13, characterized in that it comprises a reduction gear train box (38) to which the fan is connected.

15. Method for detecting an axial displacement of a turbomachine fan (12) which is capable of rotating about a longitudinal axis (XX') and which comprises a rotor disk (30) and a plurality of blades (32) with variable angular pitch mounted on the periphery of the disk, the detection method comprising the use, on the one hand, of several pitch reference members (52; 52') secured to the rotor disk and of at least one sensor (62) positioned in a fixed manner relative to the fan and on the path of the pitch reference members during rotation of the fan, to detect an axial displacement of the fan (12) from the detection of an axial displacement of the pitch reference members (52; 52'), the pitch reference members (52; 52') and said at least one sensor (62) being used for determining an angular pitch position of at least one blade (32).

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