Method and system for controlling the permeability of a lubrication circuit in an aircraft turbomachine

Abstract

A method for checking the permeability of a lubrication circuit of an aircraft turbomachine, the turbomachine comprising at least one guide bearing, the lubrication circuit being configured to circulate an upstream-downstream flow of oil between an oil inlet and an oil outlet to lubricate the guide bearing, the method comprising the steps of: measuring a first temperature (T1) of the oil upstream of the guide bearing; measuring a second temperature (T2) of the oil downstream of the guide bearing; calculating a temperature difference between the second temperature (T2) and the first temperature (T1); comparing the temperature difference (ΔT) with a predetermined expected temperature difference (ΔT0); and when the temperature difference (ΔT) is greater than the expected temperature difference (ΔT0), emitting a permeability fault signal of the lubrication circuit. Abstract figure: Figure 6

Description

Title of the invention: Method and system for controlling the permeability of a lubrication circuit of an aircraft turbomachine Technical field

[0001] The present invention relates to the field of lubrication systems mounted in an aircraft turbomachine.

[0002] In a known manner, with reference to [Fig. 1], an aircraft turbomachine 101 comprises a gas generator 110 comprising a compression stage 111 and a turbine stage 112 connected to a propulsion shaft 102 to rotate a propulsion member (not shown). The turbomachine 101 extends longitudinally along an axis X.

[0003] As shown in [Fig.l], the propulsion shaft 102 extends along the longitudinal axis X of the turbomachine 101 and is guided in rotation at the rear of the gas generator 110 by a rear bearing 103 secured to a casing of the turbomachine 101. In a known manner, the rear bearing 103 comprises a plurality of bearings 104 mounted between two rings. The propulsion shaft 102 is inserted into the rear bearing 103.

[0004] When the turbomachine 101 is in operation, the propulsion shaft 102 rotates on itself, which heats the rear bearing 103. To limit this heating, the turbomachine 101 comprises, in a known manner, a lubrication circuit 105 which allows, via injection members 106 (such as nozzles for example) to inject oil onto the rear bearing 103 to lubricate it and drain calories.

[0005] However, when the turbomachine 101 stops, the stored heat dissipates from the hottest parts, which causes the coldest parts to heat up. In operation, since the rear bearing 103 is cooled by the oil, it is a cold part. In other words, the temperature of the rear bearing 103 increases sharply when the turbomachine 101 stops and the residual oil present in the rear bearing 103 heats up. Such significant heating can lead to premature aging of the oil and its degradation.

[0006] As is known, overheating of an oil leads to the formation of solid deposits which are deposited on the inner wall of the conduits of the lubrication circuit. Such formation of solid particles is commonly referred to as "coking". The accumulation of deposits can obstruct the conduits of the lubrication circuit, and in particular the injection members, which can prevent the circulation of the oil. An alteration of the circulation of the oil in the lubrication circuit can lead to degradation of the turbomachine cooling. Degraded lubrication and cooling can prematurely wear the rear bearing, which can lead to damage to the turbomachine.

[0007] Also, it is necessary to regularly check that the lubrication circuit is not obstructed. For this, it is known to monitor the flow rate of the oil circulating in the lubrication circuit, in particular, at the level of the oil injection members.

[0008] In this respect, a verification method is known in the prior art in which oil is manually poured into the lubrication circuit during a maintenance operation. The oil flows by gravity into the lubrication circuit between an oil inlet and an oil outlet, via the injection members, according to a test duration. This test duration is compared to a reference duration, for example determined following the manufacture of the turbomachine, in order to determine whether the flow rate is lower than initially, that is to say, whether its permeability has decreased.

[0009] However, the flow duration depends directly on the exact volume of oil passing through the lubrication circuit, as well as its temperature. Since such an operation is not performed in a controlled environment (such as a laboratory, for example), the results are imprecise and error-prone. Also, it is generally necessary to repeat the verification process to confirm the measurements, which is time-consuming. In addition, since the turbomachine is mounted on the aircraft, the inlet of the lubrication circuit is difficult to access and requires an operator to be positioned on the aircraft while the cowling of the turbomachine is open, which is impractical. In addition, this requires maintaining a database with the reference flow durations of each turbomachine, which is complex.

[0010] The invention thus aims to eliminate at least some of these drawbacks by proposing a system and a method for controlling the permeability of a lubrication circuit of an aircraft turbomachine that are simple, precise and effective. The system and the method aim in particular to detect in a simple and rapid manner an obstruction of the lubrication circuit, for example for the purpose of carrying out predictive maintenance. PRESENTATION OF THE INVENTION

[0011] The invention relates to a method for controlling the permeability of a lubrication circuit of an aircraft turbomachine, the turbomachine comprising at least one guide bearing in which a propulsion shaft is rotatably mounted, the lubrication circuit being configured to circulate an oil flow from upstream to downstream between an oil inlet of the lubrication circuit and an oil outlet of the lubrication circuit to lubricate the guide bearing, the method comprising the steps of: • Measure a first oil temperature upstream of the guide bearing, • Measure a second oil temperature downstream of the guide bearing, • Calculate a temperature difference between the second temperature and the first temperature, • Compare the temperature difference with a predetermined expected temperature difference, and • When the temperature difference is greater than the expected temperature difference, issue a lubrication circuit permeability fault signal.

[0012] The method according to the invention makes it possible to detect a permeability defect in the lubrication circuit in a simple and effective manner. Advantageously, the method, which is simple to implement, allows such a check by measuring only the temperature upstream and downstream of the guide bearing. In addition, thanks to the invention, it is not necessary to know the initial state of the new turbomachine, as was the case in the prior art. A temperature measurement is very reliable since, according to one aspect of the invention, the variation in oil temperature is greater, for example, than a pressure measurement when the circulation ducts are obstructed.

[0013] Furthermore, the method according to the invention is precise and advantageously requires a single measurement, unlike the method of the prior art in which it was necessary to repeat the operation to obtain a reliable result. The control method is thus faster and can also be carried out at any time. In other words, thanks to the invention, the control method does not require a dedicated maintenance operation, which represents a significant time saving and makes it possible to limit costs.

[0014] In a preferred embodiment, the turbomachine operating at a determined speed, the expected temperature difference is predetermined for the determined speed. For a given speed, the method according to the invention advantageously makes it possible to determine an expected temperature difference between the inlet and the outlet of the lubrication circuit. Indeed, at iso-speed, such a temperature difference is simple to determine.

[0015] In one embodiment, the method comprises a step of determining a degree of permeability of the lubrication circuit from a database associating a temperature difference and a degree of permeability, the degree of permeability being determined from the temperature difference obtained.

[0016] Thanks to the invention, the degree of permeability can be determined simply and quickly from the temperature difference between the upstream and downstream of the guide bearing. The method thus makes it possible to alert in the event of excessive obstruction of the lubrication circuit, which ensures optimal operation of the lubrication circuit.

[0017] In one embodiment, a first temperature difference being calculated at a first instant, a second temperature difference being calculated at a second instant, subsequent to the first instant, the method comprises a step of comparing the first temperature difference and the second temperature difference, so as to determine a change in the permeability of the lubrication circuit. Monitoring the change in the temperature difference advantageously makes it possible to detect a drop in the flow rate of the oil flow, which makes it possible to anticipate an excessively significant defect in permeability and therefore lubrication of the turbomachine. Maintenance operations can thus be planned in advance, which is advantageous.

[0018] The invention also relates to a computer program type product, comprising at least one sequence of instructions stored and readable by a processor and which, once read by this processor, causes the steps of the method as presented previously to be carried out.

[0019] The invention further relates to a computer-readable medium comprising the computer program product as presented above.

[0020] The invention also relates to a motor system for implementing the method for controlling the permeability of a lubrication circuit as described previously, the motor system comprising: • an aircraft turbomachine comprising: • at least one guide bearing to be monitored in which a propulsion shaft is rotatably mounted, • a lubrication circuit for lubricating the guide bearing, the lubrication circuit being configured to circulate an oil flow from upstream to downstream between an oil inlet of the lubrication circuit and an oil outlet of the lubrication circuit, • a first member for measuring the temperature of the oil flow, the first measuring member, mounted upstream of the guide bearing in the lubrication circuit, being configured to measure a first temperature of the oil, • a second member for measuring the temperature of the oil flow, the second measuring member, mounted downstream of the guide bearing in the lubrication circuit, being configured to measure a second oil temperature, • a calculator configured for: • Calculate a temperature difference between the second temperature and the first temperature, • Compare the calculated temperature difference with a predetermined expected temperature difference stored in the calculator, and • When the temperature difference is greater than the expected temperature difference, issue a lubrication circuit permeability fault signal.

[0021] The engine system according to the invention makes it possible to implement the method by means of simple temperature measuring members positioned upstream and downstream of the guide bearing. The engine system thus does not require the addition of significant additional devices which would increase the mass and size of the turbomachine. In addition, the measuring members can advantageously be mounted simply and quickly on existing aircraft.

[0022] Preferably, the computer is configured to determine the expected temperature difference from a given turbomachine speed.

[0023] In one embodiment, the computer is configured to determine a degree of permeability of the lubrication circuit from a database accessible by the computer associating a temperature difference and a degree of permeability, the degree of permeability being determined from the temperature difference obtained.

[0024] Preferably, the expected temperature difference depends on a predetermined speed of the turbomachine. Also, for a known speed of the turbomachine and a calculated temperature difference, it is thus simple to determine the degree of permeability of the lubrication circuit. It is advantageously not necessary to carry out any particular manipulation by an operator. In particular, it is not necessary to access a particular inlet of the lubrication circuit, as was the case in the prior art.

[0025] In a first embodiment, the first measuring member comprises a pressure and temperature transmission member located in the lubrication circuit upstream of the guide bearing to be monitored, making it possible to limit the addition of additional devices.

[0026] Alternatively, the first measuring member is a sensor mounted in an attached manner in the lubrication circuit upstream of the guide bearing to be monitored, which makes it possible to optimally calibrate the measuring member.

[0027] In a first embodiment, the lubrication circuit comprises at least one plug and the second measuring member is mounted on said plug. Such a plug is used for draining and provides access to the second temperature upstream of the guide bearing. Preferably, the second measuring member is a adhesive patch that allows the oil temperature to be determined indirectly by determining the temperature of the cap.

[0028] Such an adhesive patch can advantageously be positioned simply and quickly on an existing plug, which limits the replacement of parts of the lubrication circuit. In addition, such a measuring device allows simple and rapid reading of the temperature.

[0029] In a second embodiment, the second measuring member is a temperature probe mounted directly in the cap, allowing direct temperature measurement of the oil flow, which allows a reliable result.

[0030] In a third embodiment, the second measuring member comprises a temperature sensor integrated into the cap, which makes it possible to reduce the size while obtaining a reliable temperature reading.

[0031] In a fourth embodiment, the second measuring member comprises a temperature sensor mounted in a circulation duct of the lubrication system. Such an embodiment allows a reliable temperature of the oil flow moving in the lubrication circuit.

[0032] The invention also relates to an aircraft comprising at least one engine system as described previously. PRESENTATION OF FIGURES

[0033] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0034] [Fig.l] is a schematic representation of an engine system comprising an aircraft turbomachine and a lubrication circuit according to the prior art.

[0035] [Fig.2] is a schematic representation of an engine system comprising an aircraft turbomachine and a lubrication circuit according to one embodiment of the invention.

[0036] [Fig.3] is a schematic representation of the lubrication circuit of [Fig.2].

[0037] [Fig.4] is a graph representing the evolution of the temperature difference between the inlet and the outlet of the lubrication circuit as a function of the oil circulation flow rate in the lubrication circuit of [Fig.3].

[0038] [Fig.5] is a schematic representation of a database associating, for a plurality of engine speeds, a flow rate with an expected temperature difference from [Fig.3].

[0039] [Fig.6] is a diagram of the steps of a control method according to an embodiment of the invention.

[0040] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0041] With reference to [Fig.2] and [Fig.3], there is shown an SM engine system for an aircraft according to an embodiment of the invention. The SM engine system comprises a turbomachine 1 comprising a lubrication circuit 5 which injects oil to lubricate the turbomachine 1 and drain the calories, so as to limit the risks of overheating of the turbomachine 1.

[0042] With reference to [Fig. 2], in this example, the turbomachine 1 extends longitudinally along an axis X. In the remainder of this document, the terms “front” and “rear” are defined with respect to the longitudinal axis X which extends from the rear to the front of the turbomachine 1. As is known, the turbomachine 1 comprises a gas generator 10 comprising a compression stage 11 and a turbine stage 12 connected to a propulsion shaft 2 to rotate a propulsion member (not shown). The turbomachine 1 is configured to operate at an engine speed R.

[0043] As shown in [Fig. 2], the propulsion shaft 2 extends along the longitudinal axis X of the turbomachine 1. The propulsion shaft 2 is guided in rotation along the longitudinal axis X by a plurality of guide bearings 3, 4 mounted in the casing of the turbomachine 1. More precisely, the propulsion shaft 2 is guided in rotation at the rear of the gas generator 10 by a rear bearing 3 and at the front of the gas generator 10 by a front bearing 4. In a known manner, each guide bearing 3, 4 comprises a plurality of bearings 31, 41 mounted between two rings. The propulsion shaft 2 is inserted into each of the guide bearings 3, 4. The guide bearings 3, 4 will not be described in more detail in this document.

[0044] The lubrication circuit 5 is configured to limit heating of the turbomachine 1 due to the rotation of the propulsion shaft 2 and therefore to the friction between the different components of the turbomachine 1. For this, the lubrication circuit 5 is configured to inject oil into the turbomachine 1, in particular at the guide bearings 3, 4. Subsequently, the lubrication circuit 5 is described for the lubrication of a guide bearing 3, 4 to be monitored. In this example, the guide bearing 3, 4 to be monitored corresponds to the rear bearing 3, however the guide bearing 3, 4 to be monitored could alternatively be the front bearing 4. Similarly, the circulation of the oil in the guide bearings 3, 4 and in particular in the rear bearing 3 is described below, but it will be understood, however, that the lubricating oil circulates in several components of the turbomachine 1.

[0045] With reference to [Fig. 2] and [Fig. 3], the lubrication circuit 5 extends in the turbomachine 1 on either side of the rear bearing 3. The lubrication circuit 5 comprises an oil inlet 51, an oil outlet 52 and a plurality of oil circulation conduits 53 mounted between the oil inlet 51 and the oil outlet 52. An oil flow H (represented in [Fig. 2] by continuous arrows) circulates in the lubrication circuit 5 from upstream to downstream from the oil inlet 51 to the oil outlet 52. In other words, the lubrication circuit 5 extends upstream and downstream of the rear bearing 3. In this example, as shown in [Fig. 2], by oil “inlet” 51 and oil “outlet” 52, we mean the inlet and the oil outlet in the gas generator 10. The oil inlet 51 and the oil outlet 52 could alternatively be placed at different positions respectively upstream and downstream of the rear bearing 3.

[0046] More precisely, as shown in [Fig. 3], the lubrication circuit 5 comprises a storage tank 55 for the oil H and a mechanical pump 56 for circulating the flow of oil H in the circulation ducts 53. The flow of oil H is then configured to pass through the entire turbomachine 1. In particular, the flow of oil H is configured to enter via the oil inlet 51, pass through the rear bearing 3 and exit via the oil outlet 52. To pass through the rear bearing 3, the lubrication circuit 5 comprises an injection member 54 (shown in [Fig. 2]) mounted directly upstream of the rear bearing 3. The flow of oil H is then configured to circulate in the lubrication circuit 5 at the outlet of the rear bearing 3 by means of a second mechanical pump 56A.The lubrication circuit 5 also comprises a cooling device 57 configured to cool the flow of oil H after it has been heated in the circulation ducts 53, for example in contact with the bearings of the rear bearing 3.

[0047] In one embodiment, the lubrication circuit 5 comprises a pressure and temperature transmission member TR, configured to measure the pressure and temperature of the oil flow H which circulates in the lubrication circuit 5. Preferably, the transmission member TR is positioned on the lubrication circuit 5 between the first mechanical pump 56 and the oil inlet 51 of the rear bearing 3. In other words, the transmission member TR is mounted upstream of the rear bearing 3.

[0048] Preferably, the lubrication circuit 5 also comprises a filter 58 mounted on the lubrication circuit 5 between the first mechanical pump 56 and the oil inlet 51 of the rear bearing 3. More preferably, the filter 58 is mounted on the lubrication circuit 5 between the first mechanical pump 56 and the transmission member TR. The filter 58 makes it possible to retain the particles present in the oil, so as to recirculate clean oil in the lubrication circuit 5 and thus limit any risk of obstruction of the lubrication circuit 5.

[0049] In a preferred embodiment, still with reference to [Fig. 3], the lubrication circuit 5 also comprises a plug, for example a magnetic plug BM, mounted on the lubrication circuit 5 downstream of the oil outlet 52 of the rear bearing 3. Such a magnetic plug BM generally comprises a filter, for example a strainer, and is mounted on the lubrication circuit 5 so as to retain the largest particles of impurities present in the oil at the outlet of the guide bearings 3, 4.

[0050] According to one aspect of the invention, the engine system SM comprises a first measuring member 6 and a second measuring member 7 of the temperature of the oil flow H. As such, each measuring member 6, 7 preferably comprises a temperature sensor.

[0051] As shown in Figures 2 and 3, the first measuring member 6 is mounted upstream of the rear bearing 3 and is configured to measure a first temperature T1 of the oil H in the lubrication circuit 5 upstream of the rear bearing 3. The second measuring member 7 is mounted downstream of the rear bearing 3 and is configured to measure a second temperature T2 of the oil H in the lubrication circuit 5 downstream of the rear bearing 3. As described previously, the first measuring member 6 and the second measuring member 7 could alternatively be mounted upstream and downstream of the front bearing 4.

[0052] In a first embodiment, the first measuring member 6 corresponds to the transmission member TR mounted on the lubrication circuit 5 upstream of the rear bearing 3, which makes it possible to limit the addition of additional elements in the lubrication circuit 5.

[0053] In a second embodiment, the first measuring member 6 is a sensor mounted in an attached manner on the lubrication circuit 5. By way of example, the first measuring member 6 is in the form of an adhesive patch stuck to one of the circulation ducts 53 of the lubrication circuit 5 in order to measure the temperature of a circulation duct 53 and to deduce therefrom the temperature of the oil H. Such an embodiment makes it possible to mount the first measuring member 6 simply and quickly and also makes it possible to simply add the first measuring member 6 to existing SM engine systems.

[0054] Alternatively, the first measuring member 6 is in the form of a temperature sensor, for example a probe, mounted inside one of the circulation ducts 53. The first measuring member 6 could alternatively be in a different form, for example in the form of a temperature measuring probe positioned in contact with one of the circulation ducts 53. The first measuring member 6 could also be positioned at an instrumented supply duct.

[0055] In one embodiment, the second measuring member 7 is in the form of an adhesive patch stuck to one of the circulation ducts 53 of the lubrication circuit 5 downstream of the rear bearing 3. The adhesive patch could alternatively be stuck to the magnetic plug BM.

[0056] In an alternative embodiment, the second measuring member 7 is a temperature probe mounted directly in the magnetic plug BM or in one of the circulation ducts 53, which allows a reliable and direct measurement. The second measuring member 7 could alternatively be in a different form, for example in the form of a temperature measuring probe positioned in contact with one of the circulation ducts 53. The second measuring member 7 could also be mounted in an oil recovery duct.

[0057] Still with reference to [Fig. 3], the engine system SM comprises a computer 9, preferably electrically connected to the first measuring member 6 and to the second measuring member 7. The computer 9 is configured to receive a first temperature T1 measured by the first measuring member 6 upstream of the rear bearing 3 and a second temperature T2 measured by the second measuring member 7 downstream of the rear bearing 3 and to calculate a temperature difference AT between the second temperature T2 and the first temperature T1 (AT=T2-T1). Alternatively, the first temperature T1 and the second temperature T2 could be recorded (for example read on an adhesive patch) by an operator who could enter the values ​​into the computer 9. The computer 9 can be integrated into an engine monitoring module, also known as “Health Monitoring”.

[0058] The computer 9 is also configured to compare the temperature difference AT with a predetermined expected temperature difference AT0. The expected temperature difference AT0 preferably corresponds to a determined speed R of the turbomachine 1. When the temperature difference AT is greater than the expected temperature difference AT0, the computer 9 is configured to emit a permeability fault signal from the lubrication circuit 5.

[0059] Indeed, as shown in [Fig. 4], for a given regime R (RA, RB, ...) of the turbomachine 1, the temperature difference AT changes as a function of the flow rate D of the oil flow H in the lubrication circuit 5 (and more particularly in the rear bearing 3). More precisely, for a given regime R, the lower the flow rate D of the oil flow H, the higher the temperature difference AT between the upstream and downstream of the rear bearing 3. According to one aspect of the invention, a temperature difference AT greater than the expected temperature difference AT0 indicates that the flow rate D of the oil flow H in the lubrication circuit 5 is insufficient. In other words, the lubrication circuit 5 is obstructed and its permeability is limited. By "limited permeability", it is understood that an insufficient quantity of oil circulates in the lubrication circuit 5 to lubricate the turbomachine 1 optimally.

[0060] In one embodiment, the computer 9 is further configured to determine a degree of permeability DP of the lubrication circuit 5 from the temperature difference AT obtained for the determined regime R. Preferably, the degree of permeability DP is determined from a database BdD associating a regime R, a temperature difference AT and a degree of permeability DP.

[0061] In this respect, [Fig.5] shows an example of a database BdD in which for a given regime RA (RB, ... RX), each temperature difference ATA-1, ATA-2, ATA-3, ... (ATB-1, ATB-2, ..., ATX-1, ATX-2, ...) is associated with a degree of permeability DPA-1, DPA-2, DPA-3, ... (DPB-1, DPB-2, ..., DPX-1, DPX-2, ...).

[0062] In one embodiment, the computer 9 is configured to calculate, at a first instant, a first temperature difference ATI between the first temperature T1 and the second temperature T2 and, at a second instant, subsequent to the first instant, a second temperature difference AT2 between the first temperature T1 and the second temperature T2. The computer 9 is then configured to compare the first temperature difference ATI and the second temperature difference AT2 and to determine a change in the temperature difference AT between the first instant and the second instant. Such an embodiment makes it possible to anticipate the obstruction of the rear bearing 3 of the lubrication circuit 5 by detecting an increase in the temperature difference AT corresponding to a decrease in the flow rate D.

[0063] A method for determining the permeability of a lubrication circuit 5 of an aircraft turbomachine 1 will now be described according to an embodiment of the invention, with reference to [Fig. 6]. In this example, an oil flow H circulates in the lubrication circuit 5 and circulates more particularly from upstream to downstream in the gas generator 10 via the guide bearing 3, 4 to be monitored. The method will be described for monitoring the rear bearing 3, however the method according to the invention also applies to monitoring the front bearing 4. Similarly, for a turbomachine 1 comprising a different number of guide bearings, the invention applies with the same advantages to any guide bearing of an aircraft turbomachine. In this example, the turbomachine 1 operates at a determined speed R.

[0064] According to the invention, the permeability of the lubrication circuit 5 is determined from a temperature difference between the upstream and downstream of the guide bearing 3, 4 to be monitored, in this example the rear bearing 3.

[0065] The method comprises a first step E1 of measuring, by the first measuring member 6, a first temperature T1 of the oil flow H upstream of the rear bearing 3. and by the second measuring member 7 of a second temperature T2 of the oil flow H downstream of the rear bearing 3.

[0066] In a second step E2, the computer 9 calculates a temperature difference AT between the upstream and downstream of the rear bearing 3 (AT=T2-T1). The computer 9 then compares, in a step E3, the calculated temperature difference AT with an expected temperature difference ATO predetermined for the determined speed R of the turbomachine 1.

[0067] In one embodiment, the computer 9 determines, in a step E4, a degree of permeability DP of the lubrication circuit 5 from the temperature difference AT obtained for the determined regime R. For this, the computer 9 determines the degree of permeability DP from a database BdD associating, for the determined regime of the turbomachine 1, a degree of permeability DP-1, DP-2, ... with a temperature difference AT-1, AT-2, ....

[0068] When the calculated temperature difference AT is greater than the expected temperature difference ATO, the computer 9 detects that the permeability of the lubrication circuit 5 is insufficient and emits a permeability fault signal of the lubrication circuit 5, in a step E5.

[0069] Indeed, the temperature difference AT is directly linked to the flow rate D of the oil flow H in the lubrication circuit 5. Also, when the rear bearing 3 is obstructed for example by the presence of deposits, the flow rate of the oil flow H decreases, the permeability of the rear bearing 3 (and therefore of the lubrication circuit 5) is limited.

[0070] In one embodiment, the computer 9 calculates, at a first instant, a first temperature difference ATI between the first temperature T1 and the second temperature T2. At a second instant, the computer 9 calculates a second difference AT2 between the first temperature T1 and the second temperature T2. The computer 9 then compares the first temperature difference ATI and the second temperature difference AT2 and determines a change in the temperature difference AT between the first instant and the second instant. In the event of detection of an increase in the temperature difference AT between the first instant and the second instant, the computer 9 sends, in this example, an alert signal corresponding to a detection of a drop in the flow rate D. In this example, such an alert signal is emitted even when the oil flow H is still circulating sufficiently.Such an embodiment makes it possible, for example, to anticipate a subsequent check, making it possible not to wait until the lubrication circuit 5 is operating in a degraded manner.

[0071] The determination method according to the invention makes it possible to prevent obstruction of the lubrication circuit and more particularly of the guide bearing to be monitored in a simple and rapid manner by calculating a temperature difference between the upstream and downstream of said guide bearing. Such a measurement can be carried out at any time during any maintenance operation (not dedicated to the lubrication circuit), or even when the aircraft is in flight.

Claims

Claims

1. Method for controlling the permeability of a lubrication circuit (5) of an aircraft turbomachine (1), the turbomachine (1) comprising at least one guide bearing (3, 4) in which a propulsion shaft (2) is rotatably mounted, the lubrication circuit (5) being configured to circulate an oil flow (H) from upstream to downstream between an oil inlet (51) of the lubrication circuit (5) and an oil outlet (52) of the lubrication circuit (5) to lubricate the guide bearing (3, 4), the method comprising the steps of: • Measuring a first temperature (T1) of the oil upstream of the guide bearing (3, 4), • Measuring a second temperature (T2) of the oil downstream of the guide bearing (3, 4), • Calculating a temperature difference (AT) between the second temperature (T2) and the first temperature (T1), • Comparing the temperature difference (AT) with a predetermined expected temperature difference (ATO),• When the temperature difference (AT) is greater than the expected temperature difference (ATO), emit a lubrication circuit permeability fault signal (5), and • Determine a degree of permeability (DP) of the lubrication circuit (5) from a database (BdD) associating a temperature difference (AT) and a degree of permeability (DP), the degree of permeability (DP) being determined from the temperature difference (AT) obtained.,

2. Control method according to claim 1, in which, the turbomachine (1) operating at a determined speed (R), the expected temperature difference (ATO) is predetermined for the determined speed (R).

3. Control method according to one of claims 1 to 2, in which, a first temperature difference (ATI) being calculated at a first instant, a second temperature difference (AT2) being calculated at a second instant, subsequent to the first instant,

4.

5. the method comprises a step of comparing the first temperature difference (ATI) and the second temperature difference (AT2), so as to determine a change in the permeability of the lubrication circuit (5). Computer program type product, comprising at least one sequence of instructions stored and readable by a processor and which, once read by this processor, causes the steps of the method according to one of claims 1 to 3 to be carried out. Engine system (SM) for implementing the method for controlling the permeability of a lubrication circuit (5) according to one of claims 1 to 3, the engine system (SM) comprising: • an aircraft turbomachine (1) comprising: • at least one guide bearing (3, 4) to be monitored in which a propulsion shaft (2) is rotatably mounted, • a lubrication circuit (5) for lubricating the guide bearing (3, 4), the lubrication circuit (5) being configured to circulate an oil flow (H) from upstream to downstream, between an oil inlet (51) of the lubrication circuit (5) and an oil outlet (52) of the lubrication circuit (5), • a first measuring member (6) of the temperature of the oil flow (H), the first measuring member (6), mounted upstream of the guide bearing (3, 4) in the lubrication circuit (5), being configured to measure a first temperature (Tl) of the oil, • a second temperature measuring device (7) of the oil flow (H), the second measuring member (7), mounted downstream of the guide bearing (3, 4) in the lubrication circuit (5), being configured to measure a second temperature (T2) of the oil, • a calculator (9) configured for: • Calculate a temperature difference (AT) between the second temperature (T2) and the first temperature (Tl), • Compare the calculated temperature difference (AT) with a temperature difference expected temperature difference (ATO) predetermined recorded in the calculator (9), • When the temperature difference (AT) is greater than the expected temperature difference (ATO), emit a lubrication circuit permeability fault signal (5), and • Determine a degree of permeability (DP) of the lubrication circuit (5) from a database (BdD) accessible by the calculator (9) and associating a temperature difference (AT) and a degree of permeability (DP), the degree of permeability (DP) being determined from the temperature difference (AT) obtained.

6. Engine system (SM) according to claim 5, in which the first measuring member (6) comprises a pressure and temperature transmission member (TR) located in the lubrication circuit (5) upstream of the guide bearing (3, 4) to be monitored.

7. Engine system (SM) according to one of claims 5 to 6, in which the lubrication circuit (5) comprises at least one plug (BM) and the second measuring member (7) is mounted on said plug (BM).

8. Engine system (SM) according to one of claims 5 to 6, in which the second measuring member (7) comprises a temperature sensor mounted in a circulation duct of the lubrication circuit (5).

9. Aircraft comprising at least one engine system (SM) according to one of claims 5 to 8.

Images