Method and system for controlling permeability of aircraft turbine engine lubrication circuit

Abstract

A method for controlling permeability of an aircraft turbine engine lubrication circuit, the turbine engine comprising at least one pilot bearing, the lubrication circuit configured to circulate an oil flow between an oil inlet and an oil outlet from upstream to downstream in order to lubricate the pilot bearing, the method comprises the steps of: measuring a first temperature (T1) of the oil upstream of the pilot bearing, measuring a second temperature (T2) of the oil downstream of the pilot bearing; calculating a temperature difference between the second temperature (T2) and the first temperature (T1); comparing the temperature difference with a preset expected temperature difference (T0); and signaling the presence of a permeability fault in the lubrication circuit when the temperature difference (T) is greater than the expected temperature difference (T0).

Description

Field of the Invention

[0001] The present invention relates to the field of lubrication systems installed in aircraft turbine engines. Background Art

[0002] It is known that, with reference Figure 1 , an aircraft turbine engine 101 includes a gas generator 110, which includes a compression stage 111 and a turbine stage 112 connected to a propulsion shaft 102 to drive a propulsion member (not shown) to rotate. The turbine engine 101 extends longitudinally along an axis X.

[0003] As Figure 1 shown, the propulsion shaft 102 extends along the longitudinal axis X of the turbine engine 101 and is guided to rotate by a rear guide bearing 103 fixed to the housing of the turbine engine 101 at the rear of the gas generator 110. It is known that the rear guide bearing 103 includes a plurality of rolling bearings 104 mounted between two rings. The propulsion shaft 102 is inserted into the rear guide bearing 103.

[0004] When the turbine engine 101 operates, the propulsion shaft 102 rotates by itself, causing the rear guide bearing 103 to heat up. To prevent overheating, the turbine engine 101 is known to include a lubrication circuit 105 that enables oil to be injected onto the rear guide bearing 103 via an injection member 106 (such as a nozzle) to lubricate the rear guide bearing 103 and dissipate heat.

[0005] However, when the turbine engine 101 stops operating, the stored heat dissipates from the hottest parts, causing the parts with lower temperature to heat up. During operation, the rear guide bearing 103 is cooled by oil, so it is a low-temperature part. In other words, when the turbine engine 101 stops operating, the temperature of the rear guide bearing 103 rises sharply, and the oil remaining in the rear guide bearing 103 heats up. Such a high temperature may cause premature aging and deterioration of the oil.

[0006] It is known that overheating of the oil causes the formation of solid deposits, which deposit on the inner wall of the lubrication circuit pipes. The formation of such solid particles is generally referred to as "coking". The accumulation of deposits may block the pipes of the lubrication circuit, especially the pipes of the injection member, thus hindering the circulation of oil. The change in the circulation of oil in the lubrication circuit may lead to a decline in the cooling performance of the turbine engine. Poor lubrication and cooling may cause premature wear of the rear guide bearing, resulting in damage to the turbine engine.

[0007] It is also crucial to regularly check whether the lubrication circuit is blocked. For this purpose, it is known to monitor the flow rate of the oil flowing in the lubrication circuit, especially at the oil injection member.

[0008] In the prior art, a control method is known, that is, oil is manually injected into the lubrication circuit during maintenance operations. Depending on the test time, the oil flows under the action of gravity via the injection member between the inlet and outlet of the lubrication circuit. This test time is compared with a reference time (such as the reference time determined after the production of the turbomotor) to determine whether the flow rate is lower than the initial value, that is, whether its permeability has decreased.

[0009] However, the duration of the flow directly depends on the exact volume and temperature of the oil flowing through the lubrication circuit. Since such operations are not carried out in a controlled environment (such as a laboratory), the results are inaccurate and prone to errors. Usually, the control method also needs to be repeated to confirm the measurement results, which is time-consuming. In addition, since the turbomotor is installed on an aircraft, the inlet of the lubrication circuit is difficult to access, requiring the operator to be on the aircraft with the turbomotor cowling open, which is impractical. In addition, a database containing the reference flow time for each turbomotor needs to be maintained, which is complex. Summary of the Invention

[0010] The present invention relates to a method for controlling the permeability of a lubrication circuit of an aircraft turbomotor, the turbomotor including 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 inlet and an outlet of the lubrication circuit so as to lubricate the guide bearing, the method comprising the following steps: - Measuring a first temperature of the oil upstream of the guide bearing; - Measuring a second temperature of the oil downstream of the guide bearing; - Calculating a temperature difference between the second temperature and the first temperature; - Comparing the measured temperature difference with a preset expected temperature difference; and - When the measured temperature difference is greater than the expected temperature difference, indicating a permeability fault in the lubrication circuit with a signal.

[0011] The method according to the present invention enables the simple and effective detection of permeability defects in the lubrication circuit. Advantageously, the method is easy to implement and this control can be achieved by measuring the temperatures upstream and downstream of the guide bearing. In addition, thanks to the present invention, it is not necessary to know the initial state of a new turbomotor as in the prior art. The temperature measurement is very reliable because, according to one aspect of the present invention, when the flow pipe is blocked, for example, the change in oil temperature is greater than the pressure measurement.

[0012] Furthermore, the method according to the invention is precise and advantageously only requires a single measurement, which is different from the methods in the prior art that require repeated operations to obtain reliable results. Therefore, this control method is faster and can be carried out at any time. In other words, thanks to the present invention, this control method does not require dedicated maintenance operations, thus saving a large amount of time and reducing costs.

[0013] The present invention also relates to a method for controlling the permeability of a lubrication circuit of an aircraft turbomotor, the turbomotor extending along a longitudinal axis extending from the rear to the front and sequentially including at least one rear guide bearing, a front guide bearing, and a lubrication tank along the longitudinal axis. A propulsion shaft is rotatably mounted in the rear guide bearing and the front guide bearing. The lubrication tank includes at least one mechanical pump for circulating an oil flow and a transmission member for transmitting oil pressure and oil temperature. The lubrication circuit is configured to circulate the oil flow from upstream to downstream between an inlet and an outlet of the lubrication circuit in order to lubricate each guide bearing. The method includes the following steps: - Measuring a first temperature of the oil upstream of one of the guide bearings, the first temperature being measured by a first measuring member installed in the lubrication tank in front of the front guide bearing, the first measuring member being used to measure the oil flow temperature; - Measuring a second temperature of the oil downstream of the guide bearing; - Calculating a temperature difference between the second temperature and the first temperature; - Comparing the measured temperature difference with a preset expected temperature difference; and - When the measured temperature difference is greater than the expected temperature difference, indicating with a signal the presence of a permeability fault in the lubrication circuit.

[0014] Therefore, the first temperature measurement is carried out upstream of the bearing inlet and at a certain distance from the bearing. The first temperature measurement is carried out by a measuring member installed in the existing lubrication tank of the engine without the need for additional measuring members. Furthermore, the first temperature measurement is independent of the bearing, and this first temperature measurement can be carried out regardless of whether the second temperature measuring member is located downstream of the rear guide bearing or downstream of the front guide bearing.

[0015] The lubrication tank is easy to maintain and is advantageously offset relative to the bearing. The first temperature measurement is carried out in a practical manner without increasing complexity or overall size.

[0016] In a preferred embodiment, when the turbomotor operates under a given operating condition, the expected temperature difference for the given operating condition is preset. For a given operating condition, the method according to the invention advantageously enables the determination of the expected temperature difference between the inlet and the outlet of the lubrication circuit. In fact, under equal operating conditions, this temperature difference is easy to determine.

[0017] In one embodiment, the method further includes the step of determining the permeability of the lubrication circuit through a database that correlates the temperature difference with the permeability, wherein the permeability is determined by the obtained temperature difference.

[0018] Thanks to the present invention, the permeability can be simply and quickly determined based on the temperature difference between the upstream and downstream of the guide bearing. Therefore, when the lubrication circuit is severely blocked, the method will provide a warning to ensure that the lubrication circuit operates in an optimal state.

[0019] In one embodiment, a first temperature difference is calculated at a first time point, and a second temperature difference is calculated at a second time point after the first time point. The method includes the step of comparing the first temperature difference with the second temperature difference to determine the change in the permeability of the lubrication circuit. By monitoring the change in the temperature difference, a decrease in the oil flow rate can be detected, thereby predicting a major defect in the permeability of the turbine engine and further predicting a major defect in the lubrication system. This means that maintenance operations can be planned in advance, which is advantageous.

[0020] The present invention also relates to a computer program product, including at least one sequence of instructions stored and read by a processor, which, when read by the processor, executes the steps of the foregoing method.

[0021] The present invention also relates to a computer-readable medium, which includes the computer program product as described above.

[0022] The present invention also relates to an engine system for implementing the method for controlling the permeability of a lubrication circuit as described above, the engine system including: - An aircraft turbine engine, including: o At least one guide bearing to be monitored, in which a propulsion shaft is rotatably mounted; o A lubrication circuit for lubricating the guide bearing, the lubrication circuit being configured to circulate the oil flow from upstream to downstream between the oil inlet and the oil outlet of the lubrication circuit; - A first measuring member for measuring the oil flow temperature, the first measuring member being mounted upstream of the guide bearing in the lubrication circuit and being configured to measure the first temperature of the oil; - A second measuring member for measuring the oil flow temperature, the second measuring member being mounted downstream of the guide bearing in the lubrication circuit and being configured to measure the second temperature of the oil; - A calculator, configured to: o Calculate the temperature difference between the second temperature and the first temperature; o Compare the measured temperature difference with a preset expected temperature difference stored in the calculator; and o When the measured temperature difference is greater than the expected temperature difference, indicate the presence of a permeability fault in the lubrication circuit with a signal.

[0023] The engine system according to the invention makes it possible to implement this method by means of simple temperature measuring elements located upstream and downstream of the guide bearing. This means that the engine system does not require the addition of significant additional equipment that could increase the weight and overall size of the turbomotor. In addition, the measuring elements can be quickly and easily installed on existing aircraft.

[0024] Preferably, the calculator is configured to determine an expected temperature difference according to a given operating condition of the turbomotor.

[0025] The invention also relates to an engine system for implementing the method for controlling the permeability of a lubrication circuit as described above, the engine system comprising: - an aircraft turbomotor extending along a longitudinal axis and comprising, in succession along the longitudinal axis: o at least one rear guide bearing, a front guide bearing and a lubrication tank to be monitored, a propulsion shaft being rotatably mounted in the rear guide bearing and the front guide bearing, the lubrication tank comprising at least one mechanical pump for circulating an oil flow and a transmission member for transmitting the oil pressure and the oil temperature, o a lubrication circuit for lubricating each guide bearing, the lubrication circuit being configured to circulate the oil flow from upstream to downstream between an inlet of the lubrication circuit and an outlet of the lubrication circuit; - a first measuring element for measuring the oil flow temperature, the first measuring element being mounted upstream of each guide bearing in the lubrication circuit and being configured to measure a first temperature of the oil, the first measuring element being mounted in the lubrication tank in front of the front guide bearing; - a second measuring element for measuring the oil flow temperature, the second measuring element being mounted downstream of the guide bearing in the lubrication circuit and being configured to measure a second temperature of the oil; - a calculator configured to: o calculate the temperature difference between the second temperature and the first temperature.

[0026] o compare the measured temperature difference with a preset expected temperature difference stored in the calculator; and o when the measured temperature difference is greater than the expected temperature difference, indicate by a signal the presence of a permeability fault in the lubrication circuit.

[0027] In one embodiment, the calculator is configured to be able to determine the permeability of the lubrication circuit by means of a database accessible by the calculator and associating the temperature difference with the permeability, the permeability being determined by the obtained temperature difference.

[0028] Preferably, the expected temperature difference depends on a predetermined operating condition of the turbomotor. Thus, for a known operating condition of the turbomotor and the calculated temperature difference, the permeability of the lubrication circuit can be easily determined. Advantageously, no special operation by the operator is required. Specifically, there is no need to approach the inlet of a specific lubrication circuit as in the prior art.

[0029] In the first embodiment, the first measuring member includes a pressure and temperature transmission member in the lubrication circuit upstream of the guiding bearing to be monitored, thus limiting the need for additional devices.

[0030] Alternatively, the first measuring member is a sensor installed in the lubrication circuit upstream of the guiding bearing to be monitored, achieving optimal calibration of the measuring member.

[0031] In the first embodiment, the lubrication circuit includes at least one plug, and the second measuring member is installed on the plug. This plug is used for draining oil and provides a measuring path for the second temperature upstream of the guiding bearing. Preferably, the second measuring member is a viscous patch, which indirectly determines the oil temperature by determining the temperature of the plug.

[0032] In one embodiment, the second measuring member is a thermosensitive viscous patch glued to the plug.

[0033] This viscous patch can advantageously be simply and quickly installed on the existing plug, thus eliminating the need to replace components of the lubrication circuit. In addition, this type of measuring member enables quick and easy temperature reading.

[0034] Preferably, the second measuring member is a removable viscous patch. Advantageously, this patch can be simply and quickly installed during any maintenance operation (not specifically for the lubrication circuit maintenance) and removed at the end of the maintenance operation. Since no mechanical tools are required for installation, the removable patch also reduces the risk of damaging the components of the lubrication circuit. In addition, the cost of this patch is low. In other words, by utilizing the first measuring member on the oil temperature and oil pressure transmission members of all engines, and by simply adding a removable patch, the permeability of the lubrication circuit can be easily controlled.

[0035] In one embodiment, the plug is a magnetic plug.

[0036] In one embodiment, the lubrication circuit includes at least one plug, and the second measuring member is installed in the plug.

[0037] In the second embodiment, the second measuring member is a temperature sensor directly installed in the plug, thus directly measuring the oil flow temperature and obtaining reliable results.

[0038] In the third embodiment, the second measuring member includes a temperature sensor integrated into the plug, which reduces the overall size and obtains reliable temperature readings.

[0039] In the fourth embodiment, the second measuring member includes a temperature sensor installed in the flow pipeline of the lubrication system. This embodiment ensures reliable temperature of the oil flow in the lubrication circuit.

[0040] The present invention also relates to an aircraft including at least one engine system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be better understood by reading the following description given by way of example and by referring to the following drawings given by way of non - limiting examples, in which the same reference numerals refer to similar objects.

[0042] Figure 1 is a schematic view of an engine system including an aircraft turbine engine and a lubrication circuit of the prior art.

[0043] Figure 2 is a schematic view of an engine system including an aircraft turbine engine and a lubrication circuit according to an embodiment of the present invention.

[0044] Figure 3 is Figure 2 a schematic view of the lubrication circuit shown.

[0045] Figure 4 is Figure 3 a graph showing the evolution of the temperature difference between the outlet and the inlet in the lubrication circuit shown as a function of the oil flow rate in the lubrication circuit.

[0046] Figure 5 is for various engine operating conditions to correlate the flow rate with Figure 3 the expected temperature difference of the database.

[0047] Figure 6 is a step diagram of a control method according to an embodiment of the present invention.

[0048] It should be noted that the drawings illustrate the present invention in detail in order to implement the present invention, and of course, the drawings are used to better define the present invention if necessary. DETAILED DESCRIPTION OF THE INVENTION

[0049] Referring to Figure 2 and Figure 3 , an engine system SM for an aircraft is shown in an embodiment of the present invention. The engine system SM includes a turbine engine 1, which includes a lubrication circuit 5 that injects oil into the turbine engine 1 to achieve lubrication and consume heat to avoid the risk of overheating of the turbine engine 1.

[0050] Referring to Figure 2 , in this example, the turbine engine 1 extends longitudinally along an axis X. In the following part of this text, the terms "front" and "rear" are defined relative to the longitudinal axis X extending from the rear to the front of the turbine engine 1. As is well known, the turbine engine 1 includes a gas generator 10, which includes a compression stage 11 and a turbine stage 12 connected to a propulsion shaft 2 to drive a propulsion member (not shown) to rotate. The turbine engine 1 is configured to operate under an engine operating condition R.

[0051] As Figure 2 shown, the propelling shaft 2 extends along the longitudinal axis X of the turbomachine 1. The propelling shaft 2 is guided in rotation along the longitudinal axis X by means of a plurality of guide bearings 3, 4 mounted in the casing of the turbomachine 1. More specifically, the propelling shaft 2 is guided in rotation at the rear of the gas generator 10 by the rear guide bearing 3 and at the front of the gas generator 10 by the front guide bearing 4. As is known, each guide bearing 3, 4 comprises a plurality of rolling bearings 31, 41 mounted between two rings. The propelling shaft 2 is inserted into the guide bearings 3, 4. The guide bearings 3, 4 will not be described in detail herein.

[0052] The lubrication circuit 5 is configured to reduce the heating of the turbomachine 1 due to the rotation of the propelling shaft 2 and the friction between the various parts. To this end, the lubrication circuit 5 is configured to inject oil into the turbomachine 1, specifically at the location of the guide bearings 3, 4. The lubrication circuit 5 for lubricating the guide bearings 3, 4 to be monitored is described below. In this example, the guide bearings 3, 4 to be monitored are the rear guide bearings 3, however, the guide bearings 3, 4 to be monitored may alternatively be the front guide bearings 4. Similarly, the circulation of the oil in the guide bearings 3, 4, specifically in the rear guide bearings 3, is described below, but it should be understood that the lubricating oil circulates in several parts of the turbomachine 1.

[0053] Referring Figure 2 and Figure 3 , the lubrication circuit 5 extends into the turbomachine 1 on either side of the rear guide bearing 3. The lubrication circuit 5 comprises an oil inlet 51, an oil outlet 52 and a plurality of oil flow conduits 53 mounted between the oil inlet 51 and the oil outlet 52. The oil flow H (represented by continuous arrows in Figure 2 ) circulates in the lubrication circuit 5 from the oil inlet 51 towards the oil outlet 52 from upstream to downstream. In other words, the lubrication circuit 5 extends upstream and downstream of the rear guide bearing 3. In this example, as Figure 2 shown, the "oil inlet" 51 and the "oil outlet" 52 respectively refer to the inlet and outlet through which the oil enters and exits the gas generator 10. The oil inlet 51 and the oil outlet 52 may alternatively be arranged at different positions upstream and downstream of the rear guide bearing 3 respectively.

[0054] More precisely, as Figure 3 shown, the lubrication circuit 5 comprises an oil storage tank 55 for the oil H and a mechanical pump 56 for circulating the oil flow H in the conduits 53. The oil flow H is then configured to pass through the entire turbomachine 1. Specifically, the oil flow H is configured to enter via the oil inlet 51, pass through the rear guide bearing 3 and exit via the oil outlet 52. In order to pass through the rear guide bearing 3, the lubrication circuit 5 comprises an injection member 54 mounted directly upstream of the rear guide bearing 3 (as Figure 2As shown). The oil flow H is then configured to circulate in the lubrication circuit 5 at the outlet of the rear guide bearing 3 by means of the second mechanical pump 56A. The lubrication circuit 5 also includes a cooling device 57 which is configured to cool the oil flow H when the oil flow H is heated by contacting the rolling bearing of the rear guide bearing 3 in the flow-through pipe 53.

[0055] More precisely, with reference to Figure 2 and Figure 3 , the turbomachine 1 includes a service system EQ which includes a plurality of aircraft equipment items. Specifically, the service system EQ includes a lubricating tank 8 in which a mechanical oil circulation pump 56 is installed. The lubricating tank 8 is installed in front of the front guide bearing 4 along the longitudinal axis X for easy access. In other words, the lubricating tank 8 is installed outside the gas generator 10.

[0056] In one embodiment, the lubrication circuit 5 includes a pressure and temperature transmitter TR which is configured to measure the pressure and temperature of the oil flow H circulating in the lubrication circuit 5. Preferably, the transmitter TR is located on the lubrication circuit 5, between the first mechanical pump 56 and the inlet port 51 of the rear guide bearing 3. In other words, the transmitter TR is installed upstream of the rear guide bearing 3. In fact, the transmitter TR is installed in the lubricating tank 8. The transmitter TR transmits the pressure and temperature of the oil flow H to a calculator in order to convey information to the pilot or to send an alarm to the pilot if necessary.

[0057] Preferably, the lubrication circuit 5 also includes a filter 58 which is installed on the lubrication circuit 5, between the first mechanical pump 56 and the inlet port 51 of the rear guide bearing 3. Preferably, the filter 58 is installed on the lubrication circuit 5, between the first mechanical pump 56 and the transmitter TR. In other words, the filter 58 is installed in the lubricating tank 8. The filter 58 intercepts the particles present in the oil so that the cleaned oil can be recycled in the lubrication circuit 5 while reducing the risk of blockage of the lubrication circuit 5.

[0058] In a preferred embodiment, still with reference to Figure 3 , the lubrication circuit 5 also includes a plug, such as a magnetic plug BM, which is installed on the lubrication circuit 5, downstream of the outlet port 52 of the rear guide bearing 3. This magnetic plug BM generally includes a filter such as a strainer and is installed on the lubrication circuit 5 in order to intercept the largest impurity particles present in the oil leaving the guide bearings 3, 4.

[0059] According to one aspect of the invention, the engine system SM includes a first measuring member 6 and a second measuring member 7 for measuring the temperature of the oil flow H. For this purpose, each measuring member 6, 7 preferably includes a temperature sensor.

[0060] As Figure 2 and Figure 3As shown, the first measuring member 6 is installed upstream of the rear guide bearing 3 and is configured to measure the first temperature T1 of the oil H in the lubrication circuit 5 upstream of the rear guide bearing 3. The second measuring member 7 is installed downstream of the rear guide bearing 3 and is configured to measure the second temperature T2 of the oil H in the lubrication circuit 5 downstream of the rear guide bearing 3. As previously mentioned, the first measuring member 6 and the second measuring member 7 can alternatively be installed upstream and downstream of the front guide bearing 4.

[0061] Preferably, the first measuring member 6 includes a transmission member TR.

[0062] In the first embodiment, the first measuring member 6 corresponds to the transmission member TR installed on the lubrication circuit 5 upstream of the rear guide bearing 3, thus eliminating the need to add other components to the lubrication circuit 5. In addition, the transmission member TR located in front of the gas generator 10, that is, at a certain distance from the bearings 3, 4, enables the first temperature measurement without considering which guide bearing 3, 4 needs to be monitored.

[0063] In the second embodiment, the first measuring member 6 is a sensor installed on the lubrication circuit 5 in an adapted manner. For example, the first measuring member 6 is in the form of an adhesive patch that is glued to one of the flow pipes 53 of the lubrication circuit 5 in order to measure the temperature of the flow pipe 53 and thereby infer the oil temperature. This type of embodiment makes the installation of the first measuring member 6 simple and quick, and it is easy to add the first measuring member 6 to an existing engine system SM.

[0064] Alternatively, the first measuring member 6 is in the form of a temperature sensor, such as a probe, which is installed on one of the flow pipes 53. Alternatively, the first measuring member 6 can be in a different form, such as in the form of a temperature measurement probe in contact with one of the flow pipes 53. The first measuring member 6 can also be located in an instrumented supply pipe.

[0065] In one embodiment, the second measuring member 7 is in the form of an adhesive patch that is glued to one of the flow pipes 53 of the lubrication circuit 5 downstream of the rear guide bearing 3. Alternatively, the adhesive patch can be glued to the magnetic plug BM. Of course, the second measuring member 7 can also be glued to a different plug.

[0066] The adhesive patch glued to the magnetic plug BM enables simple and quick installation without having to disassemble any components in the lubrication circuit 5. In this embodiment, the first measuring member 6 corresponding to the transmission member TR installed in the lubrication tank 8 and the second measuring member 7 corresponding to the adhesive patch glued to the magnetic plug BM make it possible to define the temperatures upstream and downstream of the bearings 3, 4 to be monitored without any complex preparation. A single adhesive patch can be used to measure the temperature difference in the lubrication circuit 5 between upstream and downstream in one of the bearings 3, 4, which significantly reduces maintenance costs and time. In addition, the adhesive patch can be placed on any type of existing engine without having to disassemble or replace any components.

[0067] Preferably, the adhesive patch is thermosensitive, enabling temperature reading to be achieved, for example, by a change in color or by direct reading on a scale, so as to determine the temperature simply and quickly.

[0068] Even more preferably, the adhesive patch is removable. Thus, after a maintenance operation, the second measuring member can be easily removed.

[0069] In an alternative embodiment, the second measuring member 7 is a temperature sensor directly installed in the magnetic plug BM or installed on one of the flow-through pipes 53, thus enabling reliable and direct measurement. Alternatively, the second measuring member 7 can take different forms, such as in the form of a temperature measurement probe in contact with one of the flow-through pipes 53. The second measuring member 7 can also be installed in the oil recovery pipe.

[0070] Still referring to Figure 3 , the engine system SM includes a calculator 9 which is preferably electrically connected to the first measuring member 6 and the second measuring member 7. The calculator 9 is configured to receive a first temperature T1 measured by the first measuring member 6 upstream of the rear guide bearing 3 and a second temperature T2 measured by the second measuring member 7 downstream of the rear guide bearing 3, and calculate the temperature difference ∆T between the second temperature T2 and the first temperature T1 (∆T = T2 - T1). Alternatively, the first temperature T1 and the second temperature T2 can be read by an operator (such as on the adhesive patch), and the operator then inputs the read values into the calculator 9. The calculator 9 can be integrated into an engine monitoring module also known as "health monitoring".

[0071] The calculator 9 is also configured to compare the temperature difference ∆T with a preset expected temperature difference ∆T0. The expected temperature difference ∆T0 preferably corresponds to a given operating condition R of the turbomachine 1. When the temperature difference ∆T is greater than the expected temperature difference ∆T0, the calculator 9 is configured to indicate by a signal the presence of a leakage fault in the lubrication circuit 5.

[0072] In fact, as Figure 4As shown, for a given operating condition R (RA, RB, etc.) of the turbine engine 1, the temperature difference ΔT varies with the flow rate D of the oil flow H in the lubrication circuit 5 (more specifically, in the rear guide bearing 3). More specifically, for a given operating condition R, the lower the flow rate D of the oil flow H, the greater the temperature difference ΔT between upstream and downstream of the rear guide bearing 3. According to one aspect of the present invention, when the temperature difference ΔT is greater than the expected temperature difference ΔT0, it 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 blocked and its permeability is limited. "Limited permeability" means that the amount of oil circulating in the lubrication circuit 5 is insufficient to optimally lubricate the turbine engine 1.

[0073] In one embodiment, the calculator 9 is further configured to determine the permeability DP of the lubrication circuit 5 based on the temperature difference ΔT obtained from determining the operating condition R. Preferably, the permeability DP is determined by a database BdD that correlates the operating condition R, the temperature difference ΔT, and the permeability DP.

[0074] For this purpose, Figure 5 An example of the database BdD is shown, in which, for a given operating condition RA (RB, etc., RX), each temperature difference ΔTA-1, ΔTA-2, ΔTA-3, etc. (ΔTB-1, ΔTB-2, etc., ΔTX-1, ΔTX-2, etc.) is associated with a permeability DPA-1, DPA-2, DPA-3, etc. (DPB-1, DPB-2, etc., DPX-1, DPX-2, etc.).

[0075] In one embodiment, the calculator 9 is configured to calculate a first temperature difference ΔT1 between a first temperature T1 and a second temperature T2 at a first time point, and calculate a second temperature difference ΔT2 between the first temperature T1 and the second temperature T2 at a second time point after the first time point. The calculator 9 is then configured to compare the first temperature difference ΔT1 with the second temperature difference ΔT2 to determine the change in the temperature difference ΔT between the first time point and the second time point. This type of embodiment enables the prediction of the blockage of the rear guide bearing 3 of the lubrication circuit 5 by detecting an increase in the temperature difference ΔT corresponding to a decrease in the flow rate D.

[0076] Now reference will be made to Figure 6 A method for determining the permeability of the lubrication circuit 5 of an aircraft turbine engine 1 according to an embodiment of the present invention will be described. In this example, the oil flow H circulates in the lubrication circuit 5, and more specifically, it circulates from upstream to downstream in the gas generator 10 via the guide bearings 3 and 4 to be monitored. A method for monitoring the rear guide bearing 3 will now be described, but the method according to the present invention is equally applicable to monitoring the front guide bearing 4. Similarly, for a turbine engine 1 including a different number of guide bearings, the present invention is applicable to any guide bearing of an aircraft turbine engine and has the same advantages. In this example, the turbine engine 1 operates under a given operating condition R.

[0077] According to the present invention, the permeability of the lubrication circuit 5 is determined by the temperature difference between upstream and downstream of the guide bearings 3, 4 to be monitored (the rear guide bearing 3 in this example). For this purpose, in this example, the first measuring member 6 includes a transmission member TR installed in the lubrication tank 8 in front of the front guide bearing 4, and the second measuring member 7 is a viscous patch glued to the magnetic plug BM.

[0078] The method includes a first step E1, in which the first measuring member 6 measures a first temperature T1 of the oil flow H upstream of the rear guide bearing 3, and the second measuring member 7 measures a second temperature T2 of the oil flow H downstream of the rear guide bearing 3.

[0079] In a second step E2, the calculator 9 calculates the temperature difference ΔT (ΔT = T2 - T1) between upstream and downstream of the rear guide bearing 3. Then, in step E3, the calculator 9 compares the calculated temperature difference ΔT with a preset expected temperature difference ΔT0 under the determined operating condition R of the turbomachine 1.

[0080] In one embodiment, in step E4, the calculator 9 determines the permeability DP of the lubrication circuit 5 based on the temperature difference ΔT obtained under the determined operating condition R of the turbomachine 1. To this end, the calculator 9 determines the permeability DP through a database BdD that correlates the permeabilities DP-1, DP-2, etc. with the temperature differences ΔT-1, ΔT-2, etc. under the determined operating condition of the turbomachine 1.

[0081] When the calculated temperature difference ΔT is greater than the expected temperature difference ΔT0, the calculator 9 detects insufficient permeability of the lubrication circuit 5 and indicates a permeability fault in the lubrication circuit 5 with a signal in step E5.

[0082] The temperature difference ΔT is directly related to the flow rate D of the oil flow H in the lubrication circuit 5. In addition, when the rear guide bearing 3 is blocked by deposits, for example, the flow rate of the oil flow H decreases, and the permeability of the rear guide bearing 3 (and the lubrication circuit 5) is limited.

[0083] In one embodiment, the calculator 9 calculates a second temperature difference ΔT1 between the first temperature T1 and the second temperature T2 at a first time point. At a second time point, the calculator 9 calculates a second temperature difference ΔT2 between the first temperature T1 and the second temperature T2. Then, the calculator 9 compares the first temperature difference ΔT1 with the second temperature difference ΔT2 and determines the change in the temperature difference ΔT between the first time point and the second time point. If an increase in the temperature difference ΔT is detected between the first time point and the second time point, the calculator 9 sends an alarm signal corresponding to the detected decrease in the flow rate D in this example. In this example, such an alarm signal is issued even if the oil flow H is still sufficient. For example, in this embodiment, subsequent control can be predicted, which enables the lubrication circuit 5 not to have to wait until it operates in a state of degraded performance.

[0084] The determination method according to the present invention enables the prevention of the clogging of the lubrication circuit by calculating the temperature difference between the upstream and downstream of the guide bearing. More specifically, it can simply and quickly prevent the clogging of the guide bearing to be detected. Such measurements can be carried out at any time during any maintenance operation (not specifically for the maintenance of the lubrication circuit), and can even be carried out during the flight of the aircraft.

Claims

1. A method for controlling the permeability of a lubrication circuit (5) of an aircraft turbine engine (1), characterized in that The turbomachine (1) extends along a longitudinal axis (X) extending from the rear towards the front and comprises, in succession along said longitudinal axis (X), at least one rear guide bearing (3), a front guide bearing (4) and an oil sump (8). A propulsion shaft (2) is rotatably mounted in the rear guide bearing (3) and the front guide bearing (4). The oil sump (8) comprises at least one mechanical pump (56) for circulating an oil flow (H) and a transmission member (TR) for transmitting oil pressure and oil temperature. The lubrication circuit (5) is configured to circulate the oil flow (H) from upstream to downstream between an inlet (51) and an outlet (52) of the lubrication circuit (5) so as to lubricate each guide bearing (3, 4). The method comprises the following steps: - Measuring a first temperature (T1) of the oil upstream of one of the guide bearings (3, 4), the first temperature (T1) being measured by a first measuring member (6) mounted in the oil sump (8) in front of the front guide bearing (4) and for measuring the temperature of the oil flow (H); - Measuring a second temperature (T2) of the oil downstream of the guide bearing (3, 4); - Calculating a temperature difference (∆T) between the second temperature (T2) and the first temperature (T1); - Comparing the temperature difference (∆T) with a preset expected temperature difference (∆T0); and - When the temperature difference (∆T) is greater than the expected temperature difference (∆T0), indicating by a signal the presence of a permeability fault in the lubrication circuit (5).

2. The control method according to claim 1, characterized in that When the turbomachine (1) is operating under a given operating condition (R), the expected temperature difference (∆T0) for the given operating condition (R) is predetermined.

3. The control method according to claim 1 or 2, characterized in that Including the step of determining a permeability (DP) of the lubrication circuit (5) by means of a database (BdD) associating the temperature difference (∆T) with the permeability (DP), wherein the permeability (DP) is determined by the obtained temperature difference (∆T).

4. The control method according to any one of claims 1 to 3, characterized in that, Calculating a first temperature difference (∆T1) at a first time point and a second temperature difference (∆T2) at a second time point after the first time point. The method includes comparing the first temperature difference (∆T1) with the second temperature difference (∆T2) in order to determine the change in permeability of the lubrication circuit (5).

5. A computer program product, characterized in that, Including at least one sequence of instructions stored and read by a processor, which, when read by the processor, executes the steps of the method according to one of claims 1 to 4.

6. An engine system (SM) for implementing the method for controlling the permeability of a lubrication circuit (5) as claimed in one of claims 1 to 4, characterized in that, The engine system (SM) comprises: - An aircraft turbomachine (1) extending along a longitudinal axis (X) and comprising, in succession along said longitudinal axis (X): o At least one rear guide bearing (3) to be monitored, a front guide bearing (4) and an oil sump (8), wherein a propulsion shaft (2) is rotatably mounted in the rear guide bearing (3) and the front guide bearing (4). The oil sump (8) comprises at least one mechanical pump (56) for circulating an oil flow (H) and a transmission member (TR) for transmitting oil pressure and oil temperature. The aircraft turbomachine (1) comprises: o A lubrication circuit (5) for lubricating each guide bearing (3, 4), the lubrication circuit (5) being configured to circulate the oil flow (H) from upstream to downstream between the inlet (51) and the outlet (52) of the lubrication circuit (5); - A first measuring member (6) for measuring the temperature of the oil flow (H), the first measuring member (6) being installed upstream of each guide bearing (3, 4) in the lubrication circuit (5), configured to measure a first temperature (T1) of the oil, and the first measuring member (6) being installed in a lubrication tank (8) in front of the front guide bearing (4); - A second measuring member (7) for measuring the temperature of the oil flow (H), the second measuring member (7) being installed downstream of the guide bearings (3, 4) in the lubrication circuit (5), configured to measure a second temperature (T2) of the oil; - A calculator (9), configured to: o Calculate the temperature difference (∆T) between the second temperature (T2) and the first temperature (T1); o Compare the measured temperature difference (∆T) with a preset expected temperature difference (∆T0) stored in the calculator (9); and o When the temperature difference (∆T) is greater than the expected temperature difference (∆T0), signal the presence of a permeability fault in the lubrication circuit (5).

7. The engine system (SM) according to claim 6, characterized in that, The calculator (9) is configured to determine the permeability (DP) of the lubrication circuit (5) through a database (BdD) accessible to the calculator (9) and associating the temperature difference (∆T) with the permeability (DP), the permeability (DP) being determined based on the obtained temperature difference (∆T).

8. The engine system (SM) according to claim 6 or 7, characterized in that, The first measuring member (6) includes a pressure and temperature transmitter (TR) in the lubrication circuit (5) upstream of the guide bearing (3, 4) to be monitored.

9. The engine system (SM) according to any one of claims 6 to 8, characterized in that, The lubrication circuit (5) includes at least one plug (BM), and the second measuring member (7) is installed on the plug (BM).

10. The engine system (SM) according to claim 9, characterized in that, The second measuring member (7) is a thermosensitive adhesive patch glued to the plug (BM).

11. The engine system (SM) according to claim 10, characterized in that, The second measuring member (7) is a removable adhesive patch.

12. The engine system (SM) according to any one of claims 6 to 8, characterized in that, The lubrication circuit (5) includes at least one plug (BM), and the second measuring member (7) is installed in the plug (BM).

13. The engine system (SM) according to any one of claims 6 to 8, characterized in that, The second measuring member (7) includes a temperature sensor installed in the flow pipeline of the lubrication system (5).

14. An aircraft, characterized in that, An engine system (SM) comprising at least one as claimed in any one of claims 6 to 13.

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