DETECTION AND ACCOMMODATION OF INTERMITTENT OPEN CIRCUITS ON AN ENGINE SENSOR OF AN AIRCRAFT TURBINE ENGINE

Abstract

The invention relates to a method for checking a measurement supplied by a sensor (2) of a turbine engine, said method being implemented by a computer (5) of the turbine engine. The method comprises the processing steps of: acquiring a first value of the rl measurement; comparing an increment with an increment threshold; and transmitting a measurement to be processed to the processing interface (6), said measurement being selected so as to be: equal to the value of an estimation model for the received measurement, if the increment is higher than the increment threshold, or equal to the acquired first value of the measurement if the increment is lower than the increment threshold, the method then comprising additional processing steps.

Claims

1. A method comprising: acquiring a first value of a measurement supplied by a probe forming an engine sensor of an aircraft turbine engine; comparing an increment with an increment threshold; transmitting to a processing interface a measurement to be processed which is selected: equal to a first corresponding value of a model for estimating the measurement acquired if the increment is greater than the increment threshold or equal to the first value, if the increment is less than the increment threshold.

2. The method according to claim 1 further comprising, if the increment is less than the increment thrcshold: acquiring a second value of the measurement sunnlied hv the probe, the second value being successive to the first value by a given time interval comparing a deviation between the first value and the first corresponding value, and a measurement validity thrcshold comparing a deviation between a time derivative between the first value and the second value, and a time derivative between the first corresponding value and a second corresponding value of the model, and a measurement time derivative validity threshold and updating the increment accordingly.

3. The method according to claim 2, wherein updating the increment comprises; if the deviation between the first value and the first corresponding value is greater than the measurement validity threshold, increasing the increment by 1, otherwise leaving the increment unchanged; and if the deviation between the time derivative between the first value and the second value, and the time derivative between the first corresponding value and the second corresponding value, is greater than the measurement time derivative validity threshold, increasing the increment by 1, otherwise leaving the increment unchanged.

4. The method according to claim 1, further comprising: comparing the first value with an invalidity threshold. updating an additional increment accordingly and determining a validity of one of two lanes respectively connecting measurement lanes of the probe and computer lanes of a computer of the turbine engine accordingly; wherein acquiring the first value, comparing the first value with an invalidity threshold, updating the additional increment and determining the validity of the two lanes are repeated successively on each of the computer lanes until one of the two lanes is determined to be invalid, acquiring the first value, comparing the increment with the increment threshold and transmitting to the processing interface the measurement to be proccssed being then implemented on a lane of the two lanes determined to be valid.

5. The mcthod according to claim 4, wherein the additional inerement is increased by 1 if the first value is greater than the invalidity threshold, and remains unchanged otherwise.

6. The method according to claim 5, wherein a lane of the two lanes is determined to be invalid if: the additional increment exceeds the increment threshold after the additional increment having been undated, and a last increase of the additional increment is due to a last first value acquired having been greater than the invalidity thrcshold.

7. The method according to claim 2, further comprising receiving the first corresponding value and the second corresponding value nrior to acquiring the first value and comparing the increment with the increment threshold, the first corresponding value and the second corresponding value being synchronized to the first value and the second value.

8. The method according to claim 1. further comprising defining the measurement validity threshold, the time validity thrcshold, increment, the additional increment, the increment threshold and an invalidity threshold prior to acquiring the first value and comparing the increment with the increment threshold.

9. The method according to claim 1, wherein the increment threshold is 20.

10. The method according to claim 2, wherein the measurement supplied by the probe is a temperature at high-pressure compressor inlet of the aircraft turbine engine, the measurement validity threshold being comprised between 15K and 45K and the measurement time derivative validity threshold comprised between 120K/s and 180K/s.

11. A computer program product comprising code instructions for an execution of the method according to claim 10 when the method is implemented by at least one computing unit.

Description

RAPID DESCRIPTION OF THE FIGURES

[0047] Other features, goals and advantages of the present invention will appear upon reading the detailed description that follows and with reference to the appended drawings, given by way of nonlimiting examples and in which:

[0048] FIG. 1, already described, illustrates a phenomenon of electrical relaxation on a signal acquired by a computer lane from a circuit which is the seat of intermittent openings,

[0049] FIG. 2, also already described, illustrates a signal acquired by a computer lane from a circuit which is the seat of a phenomenon of intermittent contact and the corresponding invalidation signal,

[0050] FIG. 3 illustrates an exemplary embodiment of a measurement chain configured to implement a measurement checking method,

[0051] FIG. 4 is a functional diagram of the previous steps of an exemplary embodiment of the checking method according to the invention,

[0052] FIG. 5 is a functional diagram of the processing steps of an exemplary embodiment of the checking method according to the invention,

[0053] FIG. 6 is a flowchart detailing the additional processing steps of an exemplary embodiment of the checking method according to the invention, and

[0054] FIG. 7 is a functional diagram of the initial steps of an exemplary embodiment of the checking method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0055] With reference to the figures, an exemplary embodiment of a method E for checking a measurement acquired by a probe forming a turbine engine sensor will now be described.

[0056] With reference to FIG. 3, a method E of this type can in particular be implemented within a measurement chain 1 comprising a probe 2 forming an engine sensor, said probe 2 comprising a measurement lane 3, and a computer 5, said computer 5 comprising a computer lane 4 connected to the measurement lane 3 of the probe 2. The measurement lane 3 acquires successive measurements representing a physical quantity, and transmits a timed signal representing these measurements to the computer lane 4. The computer 5 acquires the timed electrical signal, and elaborates a value of the measurement to be transmitted to a processing interface 6. The processing interface 6 returns information relative to the value of the measurement transmitted by the computer 5, and connected to a condition of the turbine engine, to the pilot 7 or a to a regulation system 8 of the turbine engine.

[0057] The probes 2 forming a sensor for which the checking method E is useful are in particular those for which an estimation mode of the measurement acquired is practicable. By way of purely illustrative examples, probes 2 of this type are: the temperature sensor at the inlet of the highpressure compressor, the exhaust gas temperature sensor (or EGT), or the position sensors (or LVDT for linear variable differential transformer). Advantageously the checking method E is applicable to temperature measurements, such as the temperature of turbine engine gaseous or liquid fluids such a lubricating oil or fuel. For gaseous fluids at high temperature, for example exhaust gases, a temperature probe of the thermocouple type is particularly suited.

[0058] With reference to FIG. 4, during a first preliminary step E0 the computer 5 receives a measurement value S.sub.est from an estimation model of the measurement acquired by the probe 2. If necessary, as will be explained later, successive measurement values S.sub.est, S.sub.est2 of an estimation model of the measurement acquired by the probe 2 can also be received.

[0059] The modeled value can for example have been elaborated from other measurement acquired elsewhere. This model can have been estimated by the computer 5, or supplied by the user or the constructor and, if necessary, stored in a memory of the computer 5. Either way, the measurement value of the estimation model is representative of a measurement of the same physical quantity as that measured by the probe 2. In addition, the estimation model is synchronized with the true electrical signal transmitted by the probe 2 on the computer 5 lane. In this regard, each measurement value extracted from the transmitted signal has a corresponding value within the estimation model, the computer 5 being configured to establish this correspondence between the measurement values successively extracted from the acquired signal and the successive measurement values of the estimation model.

[0060] Still with reference to FIG. 4, during previous steps a measurement validity threshold SVM is defined E11, and validity threshold of the measurement time derivative S.sub.VDTM is defined E12, and increment I, the value of which is zero by default, is defined E13, and an increment threshold S.sub.I is defined E14.

[0061] Certain or the totality of measurement validity thresholds S.sub.VM and of measurement time derivative S.sub.VDTM can be elaborated by studying operating cycles of the turbine engine during flights of the aircraft with no breakdown of the probe 2, i.e. without the appearance of the phenomenon of intermittent circuits, the value of the model being able to be reconstructed based on available flight data and compared with the selected value of the probe 2. When the sampling of the available flight data is insufficient to allow the elaboration of a threshold S.sub.VM, S.sub.VDTM, development test data can possibly be used to elaborate the threshold S.sub.VM, S.sub.VDTM. These thresholds S.sub.VM, S.sub.VDTM can be modified between two flights of the aircraft by a new elaboration depending on the new flight data available. The recovery of measurement data by a measurement chain 1, and comparison with estimation data by the model received during these cycles of operation, allow measuring a maximum observable deviation between the measured signal and the model signal. This deviation corresponds to real variations in the physical quantity during the operation of a turbine engine. Consequently, it is sufficient to propose a sufficiently great margin relative to this maximum observable deviation to deduce from it the validity thresholds S.sub.VM, S.sub.VDTM. It is also possible to recover data from test engines operating in nominal configuration. The variations in the physical quantity observed thus allow discriminating evolutions with a physical origin (i.e. logical during operation) from evolutions of electrical origin (i.e. intermittent contacts).

[0062] Advantageously, in the case where the physical quantity measured by the probe 2 is the high pressure compressor inlet temperature, the Applicant has observed that an optimal validity threshold S.sub.VM of the measurement is comprised between 15K and 45K, preferably between 25K and 35K, for example 30K. In addition, in this case, an optimal validity threshold of the measurement time derivative S.sub.VDTM is comprised between 120K/s and 180K/s, preferably between 140K/s and 160K/s, for example 150 K/s.

[0063] With reference to FIG. 5, once the previous steps of receiving an estimation model E0 and of defining E11, E12, E13, E14 implemented , the checking method E provides for processing steps E2, E3, E4 of the signal received on the computer lane 4. These processing steps E2, E3, E4 are implemented only when the turbine engine is started, and the initialization of the computer 5 is terminated. These two conditions guarantee that the estimation model of the measurement acquired by the probe, received during the previous step E0, is accurate.

[0064] During a first processing step E2, a first measurement value S.sub.acq is extracted from a signal representing the measurement acquired on the computer lane 3, said value S.sub.acq corresponding to the value S.sub.est of the estimation model, as previously described.

[0065] During a second processing step E3, the increment I is compared to the increment threshold S.sub.I.

[0066] During a third processing step E4, a measurement value to be processed is transmitted to the processing interface 6 which returns information relative to the condition of the turbine engine to the pilot 7 or to a regulation device 8 of the turbine engine. As can be seen in FIG. 6, the value of the measurement to be processed depends on the result of the comparison step E3.

[0067] If the increment I is greater than the increment threshold S.sub.I, the transmitted value S.sub.trans is the value of the estimation model S.sub.est corresponding to the first acquired value S.sub.acq extracted from the signal.

[0068] If the increment I is less than the increment threshold S.sub.I, the transmitted value S.sub.trans is the first acquired value S.sub.acq, and the checking method E implements additional processing steps E31, E32, E33, E34, before implementing the third processing step E4.

[0069] With reference to FIG. 6, during a first additional processing step E31, a second value S.sub.acq2 of the signal representing the measurement on the computer lane 4 is acquired, the second value S.sub.acq2 being successive to the first value S.sub.acq. These successive values S.sub.acq, S.sub.acq2 can be acquired in a given time interval T. Advantageously, this time interval T is a multiple of the period of the internal clock of the computer 5, called the real time clock (or RTC).

[0070] During a second additional processing step E32, the deviation .sub.VM between, on the one hand, the first acquired value S.sub.acq, and on the other hand, the corresponding value of the model signal S.sub.est, is compared to the measurement validity threshold S.sub.VM.

[0071] During a third additional processing step E33, the deviation .sub.VDTM between, on the one hand, the time derivative between the two acquired values S.sub.acq, S.sub.acq2, and on the other hand, the time derivative between two corresponding successive values S.sub.acq, S.sub.acq2 of the estimation model, is compared to the validity threshold of the measurement time derivative S.sub.VDTM.

[0072] As can be seen in FIG. 6, depending on the results of the second E32 and the third E33 additional processing steps, a fourth additional processing step E34 of updating the increment is implemented.

[0073] If the deviation AVM between, on the one hand, the first acquired signal value S.sub.acq, and on the other hand, the corresponding value S.sub.est of the estimation model, is greater than the measurement validity threshold S.sub.VM, then the increment I is increased by 1, otherwise the increment remains unchanged.

[0074] If the deviation .sub.VDTM between, on the one hand, the time derivative between the two acquired values S.sub.acq, S.sub.acq2, and on the other hand the time derivative between the two corresponding values of the estimation model, is greater than the measurement time derivative validity threshold S.sub.VDTM, then the increment I is increased by 1, otherwise the increment I remains unchanged.

[0075] Two embodiments of the checking method E previously described will now be detailed, with reference to FIG. 3, the second embodiment being generally favored in the implementation of the method E within the turbine engine.

[0076] The measurement chain 1 comprises a probe 2 forming an engine sensor, said probe 2 comprising two redundant measurement lanes 3a , 3b , and a computer 5, said computer comprising two computer lanes 4a , 4b connected to each of the measurement lanes 3a , 3b of the probe 2. Each of the measurement lanes 3a , 3b acquires the successive measurements representing a physical quantity, and transmits a timevarying electrical signal representing these measurements to each of the computer 5 lanes 4a , 4b . The computer 5 acquires timevarying electrical signals and transmits two respective measurement values to a processing interface 6. The processing interface 6 elaborates information connected to a condition of the turbine engine from the two values transmitted, and returns it to the pilot 7 or to a regulation system 8 of the turbine engine. In a first embodiment, one of the measurement lanes 3a is invalid. Consequently, processing steps E2 to E4 are implemented on the signal acquired by the valid measurement lane 3b . The previous steps of receiving an estimation model E0 and of definition E1 are implemented as previously described, and the increment threshold S.sub.I is set to 20. Alternatively, the previous steps E0 and E1 can have been implemented during another operating cycle of the turbine engine, or during engine tests carried out during maintenance or during tests prior to acceptance into active service of the turbine engine. The results of these steps E0, E1 were then stored, for example in a computer 5 memory. In any case, once the turbine engine is in operation, a first step E2 is implemented. During this step E2, the values of the signal representing the measurement supplied by the probe 2 are therefore acquired on the valid computer lane 4b , processed successively by the computer 5, and transmitted to the processing interface 6. Each measurement value is spaced from the following value by a time interval T corresponding to the period of the clock of the computer 5.

[0077] In a first time range, the increment I having been declared zero by default, additional processing steps E31 to E34 are implemented. Each time the measurement validity threshold S.sub.VM or the measurement time derivative validity threshold S.sub.VDTM is passed, the increment I is increased by 1. These passages are essentially due to the presence of intermittent contacts on the valid lane 3b -4b . When the increment I reaches the value of the increment threshold S.sub.I, the double breakdown is declared, and the computer uses the value of the estimation model S.sub.est until the end of the flight mission.

[0078] In a second embodiment of the checking method E, the two probe lanes 3a , 3b are valid a priori. The checking method E therefore allows detecting the simultaneous, or nearly, appearance of intermittent contacts one and/or the other of the lanes 3a , 3b , and accordingly adapting the measurement chain 1.

[0079] With reference to FIG. 4, during a preliminary additional step E15, an invalidity threshold S.sub.INV is defined. This invalidity threshold S.sub.INV is defined as is customary in the checking method of the prior art. It consists of the value of the measurement received, based on which the computer 5 ignores the signal received on one of the lanes 3a -4a , 3b -4b by estimating that an opening of the electrical circuit is present on one of the lanes 3a -4a , 3b -4b . The openings of the electrical circuit comprise in particular a short circuit or an intermittent open circuit. However, a value of the measurement exceeding an acquisition interval of the computer 5 (typically a measurement value that is physical absurd) is also considered as an opening of the electrical circuit.

[0080] The preliminary steps E11 , E12, E13, E14 are also implemented as described previously, and the increment threshold S.sub.I is set to 20 occurrences. In addition, during the preliminary step of defining the increment E13, an additional increment I.sub.S is defined, of which the value is zero by default.

[0081] Hereafter, with reference to FIG. 7, initial processing steps are implemented in parallel on each of the computer lanes 4a , 4b.

[0082] During a first initial step, the first processing step E2 is implemented in parallel based on each of the signals received on the two computer 5 lanes 4a , 4b . Each measurement acquired is further compared E2 to the value of the invalidity threshold S.sub.INV, and the additional increment I.sub.S is accordingly updated E3. More precisely, if one of the measurement values acquired on one of the lanes exceeds the invalidity threshold S.sub.INV, the additional increment I.sub.S is increased by 1, and remains unchanged otherwise.

[0083] When the additional increment I.sub.s exceeds the increment threshold S.sub.I, the last lane 3a -4a , 3b -4b having caused an increase in the value of the additional increment I.sub.s is determined to be invalid, and the situation then becomes similar to the first embodiment of the checking method E described previously. The initial steps are therefore repeated successively until one of the lanes 3a -4a , 3b -4b is declared invalid. Thereafter, the processing steps E2, E3, E4 of the checking method E are implemented on the lane determined to be valid.

[0084] Alternatively, a lane 3a -4a , 3b -4b is determined to be invalid if its cumulative breakdown time exceeds a predetermined breakdown threshold S.sub.P, for example 30 seconds. A breakdown threshold S.sub.P of this type may have been defined during the preliminary steps E15, at the same time as the invalidity threshold S.sub.INV. The cumulative breakdown time can further be obtained by the computer 5 by multiplying the number of successive increases of the increment I on a lane 3a -4a , 3b -4b by the acquisition time interval between two successive measurements S.sub.acq.

[0085] The different steps of the checking method E described previously, according to one of the embodiments described, can be implemented by a set of controllable means, or modules, for this purpose. In this regard, a computer program product comprising code instructions for the execution of a checking method E of this type can be used, when the method E is implemented by a computer unit. Likewise, the method E being able to be implemented by a set of means comprising computing equipments, a computer program product of this type can be stored on a storage means readable by computing equipment.