FR3083283A1 - LUBRICATION SYSTEM FOR AN AIRCRAFT MAIN POWER TRANSMISSION WITH IMPROVED METAL PARTICLE SENSING AND DETECTION DEVICE - Google Patents

Abstract

The present invention relates to a lubrication system (10) of a mechanical system (5) of an aircraft. Said lubrication system (10) comprises a reservoir (7) containing a lubrication liquid (4), a flow generator (11) of said lubrication liquid (4) and at least one lubrication circuit (1,2) provided with sprinklers (14), a bypass system (20), conduits (12) and a collection device (13) of metallic particles arranged in one of said conduits (12). Said bypass system (20) comprises a bypass line (22), arranged in parallel with said line (12) in which said capture device (13) is located, and a bypass device (21) configured so that said lubrication liquid (4) does not circulate in said line (12) in which said collecting device (13) is located, but circulates in said bypass line (22) when said temperature of said lubrication liquid (4) is lower than a calibration temperature (T1).

Description

Lubrication system for an aircraft main power transmission with an improved device for capturing and detecting metallic particles.

The present invention relates to the field of lubrication of mechanical transmission boxes of an engine torque. The invention is particularly intended for a power transmission box of a rotary wing aircraft.

The present invention relates to a lubrication system for a mechanical system with an improved device for capturing metallic particles. This lubrication system is particularly suitable for the lubrication of a power transmission box of a rotary wing aircraft.

A mechanical system generally comprises rotating elements, such as shafts and bearings, as well as elements for transmitting power and reducing or increasing the rotational speed, such as pinions and / or gears. It is therefore essential for the proper functioning of the mechanical system to lubricate and cool these rotating elements with a lubricating liquid, for example oil. This lubrication is generally provided by a lubrication system and has the main functions of limiting the wear and heating of these rotating elements of the mechanical system and, consequently, of prolonging its service life. Without such lubrication, the operation of the mechanical system may be rapidly degraded, if not impossible.

A lubrication system includes a flow generator, such as a pump, in order to supply lubrication liquid to a lubrication circuit and thus allow the circulation of lubrication liquid in the lubrication circuit. A lubrication system generally also includes nozzles spraying the lubrication liquid on at least the essential mechanical elements of the mechanical system as well as a reservoir recovering and storing the lubrication liquid.

Following lubrication of the mechanical system, the lubrication liquid circulating in a lubrication circuit of the lubrication system can sometimes be very hot and is then cooled in a cooling circuit generally external to the mechanical system before being used again for the lubrication of the mechanical system. This cooling circuit comprises at least one heat exchanger, for example an oil / air heat exchanger.

Furthermore, during its operation, the mechanical system can generate the appearance of metallic particles coming from the contact zones between its different rotating elements, for example at the teeth of the pinions and / or the gears as well as at the bearings. . These metallic particles generally come from normal wear and tear of these rotating elements. However, these metallic particles can also appear following a degradation of at least one of these rotating elements. In addition, metallic particles can be generated by the cooling circuit of the lubrication system.

These metal particles are then entrained in the reservoir of the lubrication system, in particular by the lubrication liquid sprayed by the nozzles, so as to pollute the lubrication liquid present in the reservoir. These metallic particles can then be injected into the lubrication circuit via the flow generator. The presence of these metallic particles can then disturb the proper functioning of the flow generator and / or obstruct a nozzle, limiting the spraying of the lubrication liquid carried out by this nozzle, or even stopping it.

In the event of such a reduction, or even a loss, of lubrication, degradations can quickly appear on the functioning of the mechanical system. The consequence of such degradations occurring on a mechanical system equipping for example a motor vehicle is the immobilization of the vehicle immediately or even after the lubrication liquid has run out. On the other hand, if this mechanical system constitutes a main power transmission box of a rotary wing aircraft, such degradations of the main power transmission box can then have catastrophic consequences such as an emergency landing, or even an aircraft crash.

In order to avoid such consequences, a lubrication system intended for the lubrication of a main power transmission box of an aircraft traditionally comprises an emergency lubrication device so as to compensate for such a reduction or else a loss of lubrication of the mechanical system.

In addition, a lubrication system may include elements allowing the filtration of the lubrication liquid and the collection of metallic particles in order to limit, or even stop, the circulation of these metallic particles with the lubrication liquid.

One or more so-called “mechanical” filtration devices are known, for example, which can be integrated into the lubrication system and make it possible to block certain metallic particles. Indeed, these mechanical filtration devices have orifices in order to allow the lubrication liquid to pass and thereby block metallic particles of dimensions greater than the dimensions of these orifices.

A first mechanical filtration device, formed for example by a strainer, can thus be arranged upstream of a flow generator, at the intake of the lubrication circuit. This first mechanical filtration device prevents certain metallic particles from entering the lubrication circuit.

A second mechanical filtration device, formed for example by a filter, can be arranged upstream and / or downstream of the cooling circuit of the lubrication liquid. A second mechanical filtration device arranged upstream of the cooling circuit thus prevents certain metallic particles, passed through the first mechanical filtration device or in the absence of this first mechanical filtration device, from entering the cooling circuit. A second mechanical filtration device arranged downstream of the cooling circuit also prevents metal particles generated by a heat exchanger from this cooling circuit or else previously trapped by this heat exchanger from being introduced into the lubrication circuit.

A third mechanical filtration device, formed for example by a strainer or a screen, can also be arranged at the level of the nozzles of the lubrication system in order to block metallic particles having escaped from the previous mechanical filtration devices before spraying the lubrication liquid. .

In order not to significantly disturb the circulation of the lubrication liquid in the lubrication system, these mechanical filtration devices have limited pressure drops, and therefore a fairly large filtration mesh, thereby allowing metallic particles of dimensions to pass through. smaller than the dimensions of the orifices of this filtration mesh. This filtration mesh includes, for example, holes of the order of a millimeter.

In addition, these mechanical filtration devices require generally heavy maintenance in view of their locations and their accessibility in order to clean them and remove the retained metallic particles.

Finally, the multiplication of mechanical filtration devices tends to increase the mass of the lubrication system, the mass being an important characteristic for any mechanical system, even critical for a mechanical system fitted to an aircraft.

There are also known magnetic devices which can also be integrated into the lubrication system in order to capture and retain the metallic particles passing nearby. In addition, such magnetic devices can be inspected during periodic maintenance visits or simply at regular intervals in order to recover the captured metallic particles. Then, an analysis of these metallic particles can possibly be carried out in order to determine their origins, in particular if they result from normal wear or from a degradation of a rotating element of the mechanical system.

In addition, such magnetic devices can directly return information on the quantity of metallic particles captured. Certain magnetic devices also make it possible to destroy certain captured metallic particles by electrical discharge.

For example, magnetic plugs can be arranged in the reservoir of a lubrication system, in particular in areas of retention of metallic particles. However, these magnetic plugs can only capture the metallic particles circulating in these retention zones, the other metallic particles being able to circulate freely.

The lubrication system can also include a magnetic device placed in the lubrication circuit, in particular in a pipe of this lubrication circuit. This magnetic device, designated by the acronym FFMP for the designation in English "Full Flow Magnetic Plug", is equipped with a powerful magnet in order to capture and retain the majority, or even all the metallic particles circulating in this pipe.

However, although it captures and retains metallic particles, this FFMP magnetic device remains subject to the force of the flow of lubricating liquid which sweeps it. Indeed, for lubrication liquids with high viscosities, in particular at low temperature, in particular during the first start of the mechanical system, part of the metallic particles captured by the magnetic device FFMP can come off from the magnetic device under the action of the flux of the lubrication liquid and then be reinjected into the lubrication circuit.

Finally, a magnetic counter for metallic particles circulating in the main lubrication circuit is known. Such a counter is arranged in the flow of the lubrication liquid. This magnetic counter, designated by the acronym ODM for the designation in English "Oil Debris Monitoring", makes it possible to count the metallic particles passing nearby, but without defining their materials or collecting them. The information provided is therefore partial, and the metallic particles detected continue to pollute the lubrication liquid and circulate in the lubrication circuit.

The object of the present invention is therefore to propose a lubrication system for a mechanical system making it possible to overcome the limitations mentioned above, by capturing and retaining metallic particles, while preventing these metallic particles from being ejected by the fluid. lubrication and reinjected into the lubrication circuit. The present invention thus aims to improve the capture as well as the detection of these metallic particles present in the lubrication liquid of the lubrication system.

According to the invention, a lubrication system of a mechanical system of a vehicle comprises:

- at least one reservoir containing a lubrication liquid,

- at least one lubrication liquid flow generator making it possible to supply at least one lubrication circuit, with the lubrication liquid, and

- At least one lubrication circuit, in which the lubrication liquid circulates and intended for lubrication of the mechanical system of the vehicle, each lubrication circuit comprising nozzles, pipes in which the lubrication liquid circulates and a particle capture device metal arranged in a pipe of this lubrication circuit.

A mechanical system generally comprises rotating elements, such as shafts in rotation on bearings and bearings, as well as elements for transmitting power and reducing or increasing the rotational speed, such as pinions and / or gears. A mechanical system allows for example the transmission of mechanical power from a power plant of the vehicle to a means of propulsion of the vehicle. The reservoir of the lubrication system is frequently constituted by a casing of this mechanical system. The mechanical system is for example a main power transmission box of a rotary wing aircraft.

It is therefore essential for the proper functioning of the mechanical system and, consequently, of the vehicle to lubricate and cool the rotating elements and the power transmission elements of the mechanical system with a lubricating liquid, for example oil.

This lubrication is ensured by the lubrication system according to the invention via one or more lubrication circuits conveying the lubrication liquid to the rotating elements. Following this lubrication of the mechanical system, the lubrication liquid heats up and is generally cooled in a cooling circuit before being used again for effective lubrication of the mechanical system.

The capture device is a magnetic device, for example a FFMP type capture device, comprising a permanent magnet or else an electromagnet. This capture device is easily removable in order to remove the magnetic particles captured for possible analysis. This capture device can also make it possible to automatically determine the quantity of metallic particles captured.

The lubrication system according to the invention is remarkable in that at least one lubrication circuit is provided with a bypass system comprising a bypass device and a bypass pipe arranged in parallel with the pipe in which the device is located. capture, the bypass system being configured so that the lubrication liquid flows either in the line in which the capture device is located, or in the bypass line. For this purpose, the bypass line is connected to the lines of this lubrication circuit upstream and downstream of the capture device.

According to a first embodiment of the lubrication system according to the invention which is the preferred embodiment, the bypass device is configured so that the lubrication liquid does not circulate in the pipe in which the capture device is located, but circulates in the bypass line when the temperature of the lubrication liquid is lower than a setting temperature T1.

In fact, as long as the temperature of the lubrication liquid circulating in this lubrication circuit is lower than the calibration temperature T1, the bypass device allows the lubrication liquid to circulate in the bypass line, by short-circuiting the capture. The lubrication liquid does not then sweep the collection device. Therefore, no capture of metallic particles by the capture device is possible. However, the metallic particles already captured by the capture device advantageously do not risk being ejected from the capture device under the action of the flow of lubricating liquid.

Conversely, when the temperature of the lubrication liquid is greater than or equal to the setting temperature T1, the lubrication liquid circulates in the pipe in which the capture device is located, and does not circulate in the bypass pipe. In this way, the lubrication liquid circulates in the pipe in which the capture device is located and therefore scans the capture device. Consequently, the metallic particles circulating in this pipe can be captured by the capture device.

In addition, the viscosity of the lubrication liquid decreases as its temperature increases. In fact, the viscosity of the lubrication liquid for a temperature greater than or equal to the calibration temperature T1 is less than its viscosity for a temperature below this calibration temperature T1.

The calibration temperature T1 is advantageously defined as a function of the characteristics of the lubrication liquid so that the lubrication liquid has, for a temperature higher than the calibration temperature T1, a viscosity sufficiently low to not eject the metallic particles captured by the capture device when the lubrication liquid circulates in the pipe comprising the capture device.

Consequently, as long as the lubrication liquid has a high viscosity which risks ejecting the metallic particles captured by the capture device, namely as long as the temperature of the lubrication liquid circulating in this lubrication circuit is lower than the setting temperature T1, the lubrication liquid circulates in the bypass line, without circulating in the line in which the capture device is located and therefore without risk of ejecting the metallic particles captured by the capture device and without risk of putting them back into circulation in the lubrication circuit.

Advantageously, as soon as the lubrication liquid has a sufficiently low viscosity to eliminate this risk of ejection of the metallic particles captured by the capture device, namely as soon as the temperature of the lubrication liquid circulating in this lubrication circuit is greater than or equal to the calibration temperature T1, the lubrication liquid no longer circulates in the bypass line, but circulates in the line in which the collection device is located and thus makes it possible to capture the metallic particles circulating in the lubrication circuit. The lubrication system according to the invention thus advantageously makes it possible to short-circuit the capture device as long as there is a risk of ejection of the metallic particles captured by the capture device.

The calibration temperature T1 is for example equal to 40 degrees centigrade (40 ° C) for a fluid of NATO standard 0-155 used as a lubrication liquid.

The bypass device is preferably positioned at the intersection of the bypass pipe and the pipe in which the capture device is located.

For example, the bypass device is formed by a valve provided with a first temperature sensor measuring the temperature of the lubricating liquid. This valve is controlled automatically, as a function of this temperature of the lubrication liquid measured by the first temperature sensor, so that on the one hand the lubrication liquid does not circulate in the pipe in which the collection device is located, but circulates in the bypass line when the temperature of the lubrication liquid is lower than the calibration temperature T1, and on the other hand the lubrication liquid circulates in the line in which the capture device is located, and does not circulate in the bypass line when the temperature of the lubrication liquid is greater than or equal to the calibration temperature T1.

According to another example, the lubrication system can also include a second temperature sensor measuring the temperature of the lubrication liquid independently of the bypass device. This second temperature sensor is for example positioned in the reservoir of the lubrication liquid from which the flow generator draws the lubrication liquid in order to supply this lubrication circuit. This second temperature sensor can also be positioned in a line of this lubrication circuit, for example between the flow generator and the bypass system.

The bypass device is then connected to the second temperature sensor and is formed by a valve controlled automatically as a function of the temperature of the lubrication liquid measured by the second temperature sensor in a similar manner to the previous example.

According to a second embodiment of the lubrication system according to the invention, the bypass device is a valve controlled automatically according to a predetermined duration of operation of the mechanical system after it has started. In this way, at the start of the mechanical system, the bypass device of the lubrication system according to the invention allows the circulation of the lubrication liquid in the bypass line, by short-circuiting the capture device. The lubrication liquid does not then sweep the collection device.

Then, after this predetermined duration of operation of the mechanical system after it has started, the bypass device allows the lubrication liquid to circulate in the pipe in which the capture device is located and does not circulate in the bypass pipe. Thus, after this predetermined period of operation of the mechanical system after it has started, the lubrication liquid reaches a temperature of I order of the calibration temperature T1 so that the viscosity of the lubrication liquid avoids the risk of ejection of the captured metallic particles by the capture device.

Furthermore, this predetermined duration of operation of the mechanical system after it has started can be variable as a function of the temperature outside the mechanical system, the rise in temperature of the lubricating liquid being able to be influenced by this outside temperature.

According to a third embodiment of the lubrication system according to the invention, the bypass device is a manually controlled valve, for example by an operator present in the vehicle, in particular the driver or the co-driver of the vehicle. In this case, this operator decides when the capture device is short-circuited and when the lubrication liquid circulates in the pipe comprising the capture device. This operator uses, for example, information on the temperature of the lubrication liquid or information on the duration of operation of the mechanical system after it has started.

In addition, the lubrication system according to the invention may include a cooling circuit intended to cool the lubrication liquid. This cooling circuit comprises for example a heat exchanger. In this case, the bypass pipe can be arranged in parallel only with the capture device so as to short-circuit only this capture device. The lubrication liquid then circulates permanently in the cooling circuit thus allowing cooling of the lubrication liquid.

However, the bypass pipe can also be arranged in parallel with the collection device and the cooling circuit so as to short-circuit this collection device and the cooling circuit simultaneously. By short-circuiting the cooling circuit, the bypass system advantageously makes it possible to accelerate the heating of the lubrication liquid which can thus quickly reach the calibration temperature T1. In this way, the duration during which the capture device is short-circuited is reduced. Consequently, the period during which the lubrication system according to the invention does not use the capture device and during which metallic particles can circulate in the lubrication circuit, independently of the use of other elements allowing the filtration of the lubrication liquid and the collection of metallic particles is reduced.

Furthermore, the lubrication system according to the invention may also include at least one mechanical filtration device. For example, a first mechanical filtration device is arranged upstream of the flow generator, limiting the quantity of metallic particles entering the lubrication circuit. A second mechanical filtration device can also be arranged downstream of a lubrication liquid cooling circuit. A third mechanical filtration device can also be arranged at the nozzles of the lubrication system.

Finally, the lubrication system can comprise at least two lubrication circuits, each of these at least two lubrication circuits comprising a device for capturing metal particles and a bypass system. For example, a lubrication system can include two main lubrication circuits and an emergency lubrication circuit.

The invention and its advantages will appear in more detail in the context of the description which follows with examples given by way of illustration with reference to the appended figures which represent:

- Figures 1 and 2, two exemplary embodiments of a lubrication system according to the invention.

The elements present in several separate figures are assigned a single reference.

Figures 1 and 2 show a mechanical system 5 respectively comprising a lubrication system 10. This mechanical system 5 comprises in particular mechanical elements 6, in particular rotating elements, such as shafts and bearings, as well as transmission elements of power and reduction or increase in rotation speed, such as pinions and / or gears. This mechanical system 5 is for example a main power transmission box fitted to a rotary wing aircraft.

The lubrication system 10 has the function of lubricating and cooling all or part of the mechanical elements 6 of this mechanical system 5.

The first exemplary embodiment of a lubrication system 10 shown in FIG. 1 has two lubrication circuits 1,2 while the second exemplary embodiment of a lubrication system 10 shown in FIG. 2 has a single lubrication circuit 1. The two lubrication circuits 1,2 of this first example are identical. These two lubrication circuits 1,2 make it possible to lubricate and cool the mechanical elements 6 of the mechanical system 5 simultaneously and possibly to compensate for a failure or a breakdown of the other lubrication circuit 1,2.

In common, these two embodiments of a lubrication system 10 include a reservoir 7 formed by a housing of the mechanical system 5 and containing a lubrication liquid 4, such as oil, a flow generator 11, such a pump, for each lubrication circuit 1,2 as well as a magnetic plug 19 arranged at the bottom of this reservoir 7. Each lubrication circuit 1,2 of these two embodiments of a lubrication system 10 comprises a cooling 15 formed by a heat exchanger, mechanical filtration devices 16, 17, nozzles 14, a device 13 for capturing metal particles, a bypass system 20 and conduits 12 connecting these different components.

The flow generator 11, the cooling circuit 15, the mechanical filtration devices 16, 17, the capture device 13 and the pipes 12 are arranged in series, each lubrication circuit 1, 2 ending in the nozzles 14 positioned at the above the mechanical elements 6 of the mechanical system 5. The bypass system 20 is itself arranged in parallel with the capture device 13 for the first example of embodiment of the lubrication system 10 represented in FIG. 1 and in parallel with the capture 13 and the cooling circuit 15 for the second embodiment of the lubrication system 10 shown in FIG. 2.

The flow generator 11 makes it possible to aspirate the lubrication liquid 4 located in the reservoir 7 and to supply with this lubrication liquid 4 each lubrication circuit 1,2 until it is sprayed on the mechanical elements 6 of the mechanical system 5 by means of the nozzles 14. The cooling circuit 15 makes it possible to cool the lubrication liquid 4 before it reaches the nozzles 14 and is sprayed on the mechanical elements 6 of the mechanical system 5.

The capture device 13 is arranged in a line 12 of each lubrication circuit 1,2 in order to capture the metallic particles liable to pollute the lubrication liquid 4. In addition, each lubrication system 10 comprises other elements allowing filtration of the lubrication liquid 4 and the collection of metallic particles in order to limit, or even stop, the circulation of these metallic particles in each lubrication circuit 1, 2 with the lubrication liquid 4.

In particular, the magnetic plug 19 arranged at the bottom of the reservoir 7 makes it possible to capture the metal particles located near it.

According to the two exemplary embodiments of the lubrication system 10, each lubrication circuit 1,2 also includes a first mechanical filtration device 17 arranged upstream of the flow generator 11, preventing certain metallic particles located in the reservoir 7 from entering the lubrication circuit 1,2, and a second mechanical filtration device 16 arranged downstream of the cooling circuit 15.

In addition, for the first exemplary embodiment of the lubrication system 10, each lubrication circuit 1,2 also includes third mechanical filtration devices 18, a third mechanical filtration device 18 being arranged downstream of each nozzle 14 in order to block metallic particles having escaped from the previous mechanical filtration devices 16, 17 before spraying the lubrication liquid 4.

The bypass system 20 includes a bypass device 21 and a bypass line 22. The bypass device 21 is a so-called "three-way, two position" valve positioned at the intersection of the bypass line 22 and the line 12 in which the capture device 13 is located. In this way, the lubrication liquid 4 arriving from the flow generator 11 can be directed, depending on the position of this “three-way two position” valve forming the bypass device 21, either in the pipe 12 in which the capture device 13 is located, that is to say in the bypass pipe 22.

For the first embodiment of the lubrication system 10 shown in FIG. 1, the bypass line 22 is arranged in parallel with the line 12 in which the collection device 13 is located so as to allow the lubrication liquid 4 to be short -circuit the capture device 13. In addition, the bypass device 21 is provided with a first temperature sensor 25 measuring the temperature of the lubrication liquid 4 entering this bypass device 21.

This bypass device 21 is then automatically controlled, as a function of this temperature of the lubrication liquid 4 measured by the first temperature sensor 25. Thus, the bypass device 21 takes a first position when the temperature of the lubrication liquid 4 is lower at a setting temperature T1 so that the lubrication liquid 4 circulates in the bypass line 22 by short-circuiting the line 12 in which the collection device 13 is located, and a second position when the temperature of the lubrication liquid 4 is higher or equal to the setting temperature T1 so that the lubrication liquid 4 circulates in the line 12 in which the collection device 13 is located, and does not circulate in the bypass line 22.

Consequently, the lubrication liquid 4 does not circulate in the line 12 in which the collection device 13 is located when this lubrication liquid 4 is at a temperature below the calibration temperature T1 and therefore has a high viscosity risking d eject the metallic particles captured by the capture device 13. The bypass device 21 allows in this case the circulation of the lubrication liquid 4 in the bypass line 22 in order to reach the nozzles 14 after passing through the cooling circuit 15 and the second mechanical filtration device 16 without scanning the capture device 13.

Conversely, when the lubrication liquid 4 is at a temperature greater than or equal to the setting temperature T1 and in fact has a lower viscosity eliminating the risk of ejection of the metallic particles captured by the capture device 13, the bypass 21 allows the circulation of the lubrication liquid 4 in the pipe 12 in which the capture device 13 is located. The lubrication liquid 4 then scans the capture device 13 which can capture the metallic particles circulating in this pipe 12.

The second embodiment of a lubrication system 10 shown in FIG. 2 has an operation substantially similar to the first example previously described. However, the bypass device 21 does not include the first temperature sensor 25, but the lubrication system 10 includes a second temperature sensor 27 arranged in the tank 7 and measuring the temperature of the lubrication liquid 4 located in this tank 7 The bypass device 21 is then connected to the second temperature sensor 27 and automatically controlled in a similar manner to the first example as a function of the temperature of the lubrication liquid 4 measured by the second temperature sensor 27.

In addition, the bypass line 22 is arranged in parallel with the capture device 13 and the cooling circuit 15 so as to short-circuit simultaneously this capture device 13 and the cooling circuit 15. Therefore, as long as the temperature of the lubrication liquid 4 located in the reservoir 7 has a temperature below the setting temperature T1, the lubrication liquid 4 circulates in the bypass line 22 by short-circuiting the cooling circuit 15 and is therefore not cooled. Consequently, the lubrication liquid 4 heats up quickly and reaches a temperature greater than or equal to the setting temperature T1 more quickly than for the first embodiment of a lubrication system 10. The time during which the lubrication liquid 4 does not scan the capture sensor 13 is then advantageously reduced.

Furthermore, the bypass device 21 can also be controlled automatically by another parameter of the mechanical system 5 than the temperature of the lubrication liquid 4. For example, the bypass device 21 can be controlled automatically according to the duration of operation of the mechanical system 5 after it has started, the bypass device 21 bypassing the capture device 13 for a predetermined period of operation of the mechanical system 5 after it has started.

The bypass device 21 can also be controlled manually, for example by a pilot or a co-driver of the vehicle equipped with the mechanical system 5.

Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to identify exhaustively all the possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims (12)

1. Lubrication system (10) of a mechanical system (5) of a vehicle, said lubrication system (10) comprising - at least one reservoir (7) containing a lubrication liquid (4), - at least one flow generator (11) of said lubrication liquid (4) allowing at least one lubrication circuit (1,2) to be supplied with said lubrication liquid (4), and - at least one lubrication circuit (1,2) in which circulates said lubrication liquid (4) and intended for lubrication of said mechanical system (5) of said vehicle, said at least one lubrication circuit (1,2) being provided nozzles (14), pipes (12) in which said lubrication liquid (4) circulates and a device (13) for collecting metallic particles arranged in a pipe (12) of said lubrication circuit (1,2) , characterized in that at least one lubrication circuit (1,2) is provided with a bypass system (20) comprising a bypass device (21) and a bypass line (22) arranged in parallel with said line (12) in which said capture device (13) is located, said bypass system (20) being configured so that said lubricating liquid (4) flows either in said line (12) in which said capture device is located (13), either in said line d e bypass (22). 2. Lubrication system (10) according to claim 1, characterized in that said bypass device (21) is configured so that on the one hand said lubricating liquid (4) does not circulate in said line (12) in which is located said capture device (13), but circulates in said bypass line (22) when the temperature of said lubricating liquid (4) is lower than a calibration temperature (T1), and secondly said liquid lubrication (4) flows in said line (12) in which is located said capture device (13) and does not flow in said bypass line (22) when the temperature of the lubrication liquid (4) is greater than or equal to said calibration temperature (T1). 3. Lubrication system (10) according to claim 2, characterized in that said bypass device (21) is provided with a first temperature sensor (25) measuring the temperature of said lubrication liquid (4) and automatically controlled by function of said temperature of said lubricating liquid (4) measured by said first temperature sensor (25). 4. Lubrication system (10) according to claim 2, characterized in that said lubrication system (10) comprises a second temperature sensor (27) measuring the temperature of said lubrication liquid (4) and said bypass device (21 ) is a valve controlled automatically as a function of said temperature of said lubrication liquid (4) measured by said second temperature sensor (27). 5. Lubrication system (10) according to claim 1, characterized in that said bypass device (21) is automatically controlled according to an operating time of said mechanical system (5) after it has started. 6. Lubrication system (10) according to claim 1, characterized in that said bypass device (21) is manually controlled. 7. lubrication system (10) according to any one of claims 1 to 6, characterized in that said lubrication system (10) comprises a cooling circuit (15) intended to cool said lubrication liquid (4), and said bypass line (22) is arranged in parallel with said cooling circuit (15) so that said lubrication liquid (4) circulates either in said cooling circuit (15) and in said line (12) in which is located said capture device (13), either in said bypass line (22). 8. Lubrication system (10) according to any one of claims 1 to 7, characterized in that said lubrication system (10) comprises at least two lubrication circuits (1,2), each of said at least two circuits of lubrication (1,2) comprising said collecting device (13) of metallic particles and said bypass system (20). 9. Lubrication system (10) according to any one of claims 1 to 8, characterized in that said lubrication system (10) comprises at least one mechanical filtration device (16,17,18). 10. Lubrication system (10) according to any one of claims 1 to 9, characterized in that said capture device (13) is a magnetic device. 11. Lubrication system (10) according to any one of claims 1 to 10, characterized in that said capture device (13) makes it possible to determine the quantity of metallic particles captured. 5 12. Lubrication system (10) according to any one of claims 1 to 11, characterized in that said vehicle is an aircraft and said mechanical system (5) is a main power transmission box of said aircraft.