Fuel in oil detection device by gas phase analysis

Abstract

Turbomachine comprising a lubrication circuit (20) traversed by a lubricant (21) and a supply circuit (40) traversed by a fuel 41, the lubrication circuit (20) comprising an enclosure (22° in which a liquid phase (23) and a gaseous phase (24) are established, the lubrication circuit (20) also comprising a sensor (30) arranged to detect the presence of fuel vapor (41) in the gaseous phase (24). Aircraft provided with such a turbomachine. Method for detecting leaks. Figure for the abstract: Figure 2

Description

Title of the invention: TITLE OF THE INVENTION Device for detecting fuel in oil by gas phase analysis Technical field

[0001] The invention relates to the field of engine lubrication circuits and more particularly to the prevention of pollution of such circuits. STATE OF THE PRIOR ART

[0002] In aircraft the lubrication system is essential to ensure the proper functioning of the engines. However, the lubrication system can be contaminated by fuel, which can cause problems with engine performance and flight safety, particularly due to the risk of ignition. The detection of fuel in the lubrication system is therefore crucial to ensure the reliability and safety of aircraft.

[0003] Heat exchangers are used to transfer heat generated by engines from the lubrication system to the fuel system to preheat the fuel before it is injected into the engines. These heat exchangers between the lubrication system and the fuel system can leak, which can cause contamination of the lubrication system with fuel.

[0004] There are several fuel detection technologies in the lubrication system for aircraft, such as infrared absorption spectroscopy, Raman spectroscopy, and electrical impedance analysis. These technologies are designed to detect the presence of fuel in different parts of the lubrication system, including filters, heat exchangers, and lines. Fuel detection systems must be robust and reliable to operate under varying environmental conditions, such as high temperatures and pressures, as well as in environments with vibration and shock.

[0005] Since fuels and lubricants have similar chemical properties, it is difficult to clearly establish the presence of fuel in the oil for low concentrations of fuel in the lubricant. In view of the effects of the presence of fuel in the oil, even at very low concentrations, it is necessary to have a reliable and sensitive device. SUBJECT OF THE INVENTION

[0006] The invention aims to improve the sensitivity of fuel detection in a lubricant circuit. Statement of the invention

[0007] For this purpose, a turbomachine is provided comprising a lubrication circuit traversed by a lubricant and a supply circuit traversed by a fuel, the lubrication circuit comprising an enclosure in which a liquid phase and a gaseous phase are established, the lubrication circuit also comprising a sensor arranged to detect the presence of fuel vapor in the column.

[0008] We then obtain a turbomachine equipped with a reliable and robust measuring device which analyses a particular parameter (gas phase) which is naturally denser in information and the analysis of which is easier and can be carried out using robust and reliable sensors.

[0009] According to other particular, non-exclusive and optional embodiments of the invention: - a fluid connection between the sensor and the enclosure includes an anti-splash device. - - the anti-splash device comprises a column and / or a grid and / or a membrane; - the sensor is a platinum wire catalytic sensor; - the enclosure is an oil reservoir or an oiled air pipe; - the turbomachine includes a device for generating the gas phase; - the gas phase generation device comprises a device for heating.

[0010] The invention also relates to an aircraft comprising a turbomachine as described above as well as a method for detecting a leak from a supply circuit traversed by a fuel to a lubrication circuit traversed by a lubricant in such a turbomachine, the method comprising the following steps: - taking a portion of the gaseous phase from the enclosure; - detect the presence of fuel vapor in the gas phase; - issue an alert when the gas phase contains a quantity of vapor fuel above a predetermined threshold.

[0011] Advantageously, the method comprises an additional step of generating the gas phase, preferably by heating.

[0012] Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention. Brief description of the drawings

[0013] Reference will be made to the attached figures, among which: [Fig.l] [Fig.l] is a schematic cross-sectional representation of a turbomachine; [Fig.2] [Fig.2] is a partial schematic plan view of a supply circuit and a carburetion circuit according to the invention; [Fig.3] [Fig.3] is a schematic representation of the sensor of [Fig.2].

[0014] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0015] In a turbomachine, here a turbojet marked 1 in [Fig.l], the air is admitted into an inlet sleeve 2 to pass through a fan comprising a series of rotating blades 3 before splitting into a central primary flow which circulates in a vein called a circulation vein of a primary air flow and a secondary flow surrounding the primary flow.

[0016] The primary flow is compressed by compressor stages 4 and 5 before reaching a combustion chamber 6, after which it expands by passing through turbines 7, before being evacuated, generating thrust. The secondary flow is propelled directly by the fan to generate the main thrust.

[0017] The compressor stages 4 and 5 comprise fixed distributors regularly spaced around a shaft 8 mounted for rotation around a longitudinal axis AX in a nacelle 9 surrounding the assembly. The blades of the compressor stages 4 and 5 and of the turbines 7 are integral in rotation with the shaft 8. The shaft 8 is mounted for rotation relative to the nacelle 9 using several bearings 10 lubricated with oil and which are confined in enclosures 11.

[0018] In the present text, the terms "inner" or "internal" and "outer" or "external" are used with reference to the position or orientation relative to the axis of rotation of the turbine of the turbojet engine 1. In the present text, the terms "upstream" and "downstream" are used with reference to the position or orientation of an element according to the direction of air flow in the turbojet engine 1. An axial direction, a radial direction which is orthogonal to the axial direction and a circumferential direction which is orthogonal to the axial and radial directions are also defined.

[0019] The turbojet 1 comprises a lubrication circuit 20 traversed by a lubricant 21 and a supply circuit 40 traversed by a fuel 4L. The lubrication circuit 20 comprises an enclosure 22 - here a tank - in which a liquid phase 23 and a gaseous phase 24 of the lubricant 21 are established. The lubrication circuit 20 comprises a pump 25 and is connected to a heat exchanger 50 to constitute the hot circuit. The supply circuit 40 is also connected to the exchanger 50 to constitute the cold circuit. The calories from the lubrication circuit 20 are thus transferred to the supply circuit 40.

[0020] An oiled air pipe 26 is connected to the enclosure 22. A column 27 is connected to the pipe 26 by its first end 28 to be fluidically connected to the enclosure 22 so as to be traversed by the gaseous phase 24. The second end 29 of the column 27 is provided with a sensor 30 of the platinum wire catalytic type. The end 28 is equipped with an anti-splash device, here a membrane 31.

[0021] An electric heater 60 extends against a wall - here a bottom 22.1 - of the enclosure 22. A suction device, such as a vacuum pump or jet pump, can also be used to create the vapor phase. It is sufficient to place it at the top of the oiled air pipe 26. It is then possible to add between the enclosure 22 and the pipe 26, an anti-splash device like that at the end 28, in order to guarantee the presence only of vapor in the pipe 26 and in the suction device at its top.

[0022] The pump 25, the sensor 30 and the electric heater 60 are connected to a control and command unit 70.

[0023] The sensor 30 and its operation will be described in more detail with reference to [Fig. 3]. The sensor 30 comprises a platinum wire 32 which describes a first set of turns 33 and a second set of turns 34. The first set 33 is covered with a catalyst 35 to constitute a catalytic wire measuring resistive circuit and the second set 34 is covered with a deactivator 36 to constitute a reference resistive circuit. The assemblies 33 and 34 are respectively protected by a ceramic coating 33.1 and 34.1 and have a common terminal 37. The first set 33 comprises a free measuring terminal 38 and the second set 34 comprises a free reference terminal 39.

[0024] The sensor 30 operates by measuring the electrical conductivity of the platinum wire 32.

[0025] The catalyst 35 of the platinum wire 32 allows the fuel vapor molecules to react with the oxygen naturally present in the air. This reaction modifies the physical properties of the platinum wire and in particular its electrical conductivity and therefore the voltage between the terminals 37 and 38. The voltage measured between the terminals 37 and 39 of the reference electrode provides a stable reference for measuring the electrical conductivity of the catalytic platinum wire and thus cancels out the effects of environmental parameters that may affect the measurement between the terminals 37 and 38, such as, for example, the ambient temperature and the ambient pressure.

[0026] When fuel vapor molecules 41 are present in the gas phase 24, they react with the catalyst 35 on the wire 32, changing its electrical conductivity. This resistance change is measured and is proportional to the concentration of fuel vapor in the gas phase 24.

[0027] In operation, the device of the invention follows the following steps. According to a first step, the unit 70 controls the starting of the heater 60 in order to generate the gaseous phase 24. According to a second step, the column 27 takes a portion of the gaseous phase 24 from the enclosure 22 and brings it to the sensor 30. According to a third step, the unit 70 measures the current between the terminals 37 and 38 and carries out a measurement compensation using a measurement carried out between the terminals 37 and 39. The unit 70 interprets the results obtained and detects or not the presence of fuel vapor 41 in the gaseous phase 24. According to a last step, the unit 70 emits a alert when the gas phase 24 contains a quantity of fuel vapor 41 greater than a predetermined threshold.

[0028] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0029] In particular, - although here the sensor is located at the end of the column, the invention also applies to a device without a column in which the sensor would be located on a wall of the oiled air duct or directly in the enclosure; - although here the column is connected to the pipe, the invention also applies to other methods of connection between the column and the enclosure, such as for example a branch tee; - -although here the sensor is a platinum wire catalytic sensor, the invention also applies to other types of sensors arranged to detect the presence of fuel vapor in the column, such as for example an infrared sensor or a Davy type sensor or an electrochemical detector; - although here the anti-splash device comprises a membrane, the invention also applies to other types of anti-splash device such as for example a grid or a baffle; - although here heating is used to generate the gas phase, the invention also applies to a measuring device without heating, the gas phase being generated by natural evaporation.

Claims

Claims

1. Turbomachine (1) comprising a lubrication circuit (20) traversed by a lubricant (21) and a supply circuit (40) traversed by a fuel 41, the lubrication circuit (20) comprising an enclosure (22) in which a liquid phase (23) and a gaseous phase (24) are established, the lubrication circuit (20) also comprising a sensor (30) arranged to detect the presence of fuel vapor (41) in the gaseous phase (24) in which a fluid connection between the sensor (30) and the enclosure (22) comprises an anti-splash device (31).

2. Turbomachine (1) according to claim 1, wherein the anti-splash device (31) comprises a column (27) and / or a grid and / or a membrane (31).

3. A turbomachine (1) according to any preceding claim, wherein the sensor (30) is a platinum wire catalytic sensor (32).

4. Turbomachine (1) according to any one of the preceding claims, in which the enclosure (22) is an oil reservoir or an oiled air pipe (26).

5. Turbomachine according to any one of the preceding claims, comprising a device (60) for generating the gas phase (24).

6. Turbomachine (1) according to claim 5, in which the device for generating the gas phase comprises a heating device (60).

7. Aircraft comprising a turbomachine (1) according to any one of the preceding claims.

8. Method for detecting a leak from a supply circuit (40) through which a fuel (41) flows to a lubrication circuit (20) through which a lubricant (21) flows in a turbomachine (1) according to any one of claims 1 to 6, comprising the following steps: - taking a portion of the gas phase (24) from the enclosure (22); - detecting the presence of fuel vapor (41) in the gas phase (24);

9. - issue an alert when the gas phase (24) contains a quantity of fuel vapor (41) greater than a predetermined threshold. Leak detection method according to claim 8, comprising an additional step of generating the gas phase (24), preferably by heating.

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