Assembly and method for detecting metal filings

Abstract

One aspect of the invention relates to an assembly (E) comprising a closed rotating enclosure (1), a mechanical system (2) and a lubrication circuit (3) passing through the rotating enclosure (1), the enclosure comprising an exterior wall (11) with an axis of revolution X, and an interior wall (10) facing the exterior wall (11), the assembly being characterized in that it comprises a magnetic sensor (5) and that the interior wall (10) has n cavities (12) uniformly distributed circumferentially, such that n ≥ 2.

Description

DESCRIPTION TITLE: SET AND METHOD FOR THE DETECTION OF FILLINGS TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of mechanical transmissions and more particularly rotary transmissions.

[0002] The invention relates in particular to those with lubrication in a closed rotating enclosure. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Mechanical transmissions, like all moving parts, are subject to wear over their lifespan, for example, due to friction resulting from contact between two gears or two bearings, or due to shocks or intense friction between rotating parts caused by strong and / or abnormal vibrations. Whatever the cause, wear of these parts leads to the formation of particles that detach from the parts and are carried away by the lubricating fluid. Since rotating parts are generally metallic, the particles resulting from wear are conductive and are usually in the form of metal shavings (metallic particles). These parts are most often made of a ferromagnetic metal such as iron, meaning it is attracted to a magnetic element such as a magnet. These metal shavings allow for the detection of wear or damage to a part.On the other hand, this metal filings also degrade the lubricating properties of the lubricating fluid, so it is important to remove it.

[0004] As described in French patent FR 2 957 823, a magnetic plug is used to trap metal filings, which can then be removed from the lubrication system by removing the plug and dispensing the filings. For rotating parts, a rotating mechanical magnetic plug (mounted on the rotating parts) can be used, but this is cumbersome to implement. An electrical magnetic plug can also be used when the mechanical system to be lubricated is critical.

[0005] It is also possible to mount an electric magnetic stop on a rotating part, but this is very restrictive because it requires the use of a rotating collector: which is bulky and unreliable.

[0006] Detecting metal shavings is essential for identifying potential damage to rotating mechanical components (bearings, gears, and mechanical transmission components). This function is currently performed by magnetic plugs, both electric and non-electric. The magnetic plug is strategically positioned within the oil circuit, and the magnetic interaction of the plug's magnet captures particles carried by the lubricating fluid. The mechanical magnetic plug is a simple magnet that captures the particles. It is checked manually or visually by an operator during maintenance.

[0007] The magnetic plug, on the other hand, consists of a magnet and two electrodes electrically insulated from each other. The accumulation of metal shavings due to magnetic interaction forms a conductive bridge between the two electrodes. Appropriate electronics can display a warning light on the dashboard, alerting the user or the pilot in the case of an aircraft. However, for these systems to function, the particles must be transported (by the lubricating fluid) to the magnetic plug.

[0008] In some cases, such as on a rotating shaft, lubrication requires the oil to be kept in a closed rotating chamber. An oil level is maintained by centrifugal force, and a minimum quantity of oil is retained in the chamber even when the system is stopped. This operation hinders the detection of metal shavings: the oil retention also results in the retention of any particles generated within the chamber. Since the shavings are not transported to the magnetic plug, they are not detected. SUMMARY OF THE INVENTION

[0009] The invention offers a solution to the problems mentioned above, by allowing the collection of filings and the measurement of their quantity in the lubrication circuit.

[0010] The assembly according to the invention comprises a closed rotating chamber, a mechanical system, and a lubrication circuit passing through the rotating chamber. the enclosure comprising an outer wall of revolution with axis X and an inner wall opposite the outer wall, it is characterized in that it comprises a magnetic sensor and that the inner wall comprises n cavities uniformly distributed circumferentially, such that n > 2.

[0011] The filings can thus be concentrated locally in these cavities by centrifugal force. The higher the number n of reservoirs, the lower the concentration of filings will be per cavity. To limit the effects of imbalance, there will be at least two diametrically opposed cavities, or more cavities uniformly distributed around the periphery of the inner wall.

[0012] Advantageously, the magnetic sensor is a variable reluctance inductive sensor. This sensor can detect the passage of both metal filings and metallic particles.

[0013] Advantageously, the cavities are surrounded by a conical shape directed towards each cavity. This conical shape consists of slopes that guide the filings towards the cavities by centrifugal force.

[0014] Advantageously, the cavities have a conical rim. This rim allows the filings to be directed towards the bottom of the cavity by centrifugal force on one side and to be retained once they are in the cavity on the other side.

[0015] Advantageously, the inner wall has an elliptical cross-section along the X-axis, and the cavities are located at the vertices of the ellipse. The elliptical shape of the inner wall, combined with centrifugal force, will cause the filings to accumulate towards the apogee, that is, the vertex of the ellipse defined as the extremities of the major axis, or major axis of the ellipse. The positioning of the cavities at this point optimizes the accumulation of filings.

[0016] Advantageously, the cavities have bottoms made of non-magnetic material. The magnetic permeability of the material used for the cavity bottom allows for good transmission of the magnetic field in the lubrication circuit. For example, a plastic or other non-metallic material can be used. To reduce the air gap between the sensor and the filings, the thickness of the material at the bottom of the boss should be as small as possible, between 0.5 and 5 mm.

[0017] Advantageously, the magnetic sensor is fixed. The cavities and centrifugal force allow the filings to be grouped in certain defined areas without They require a magnetic field to concentrate, so it is possible to use a static magnetic sensor.

[0018] Advantageously, the sensor is attached to a housing surrounding the enclosure.

[0019] Advantageously, the lubricant in the lubrication circuit is oil.

[0020] The invention also relates to a method for measuring the quantity of metal filings in an assembly having at least one of the preceding characteristics, and in which a cavity, upon passing in front of the inductive sensor, creates an electrical signal in said inductive sensor with an amplitude proportional to the quantity of metal filings, for example iron, in that cavity. It is thus possible to display an indicator light on the dashboard to warn the user when the concentration of metal filings is too high.

[0021] Other advantages may also become apparent to the person skilled in the art upon reading the examples below, illustrated by the attached figures, given for illustrative purposes. BRIEF DESCRIPTION OF THE FIGURES

[0022] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0023] [Fig. 1] is a longitudinal section of a closed enclosure of the prior art;

[0024] [Fig. 2] is a longitudinal section of a closed enclosure according to the invention;

[0025] [Fig. 3] is an axial cross-sectional view of a closed enclosure according to a first example of the invention;

[0026] [Fig. 4] is a detail of a cavity in figure 3;

[0027] [Fig. 5] is a detail of a variant of the cavity in figure 3

[0028] [Fig. 6] is the electrical signal from the variable reluctance sensor during the rotation of the enclosure. DETAILED DESCRIPTION

[0029] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0030] Throughout this description, the inner part of the enclosure will be referred to as "interior," and the outer part of the enclosure as "exterior." An enclosure whose only openings are the lubricant inlet and outlet is called a "closed enclosure."

[0031] The term "limaille" can be used interchangeably in the singular or plural.

[0032] Assembly E of the prior art illustrated in Figure 1 comprises a closed enclosure 1, a mechanical system 2 to be lubricated, and a lubrication circuit 3. The enclosure 1 and the mechanical system 2 rotate about an axis X. The enclosure includes an inner wall 10 and an outer wall 11. The lubrication circuit 3 includes an inlet 30 for the supply of lubricant, for example, oil, the interior of the enclosure 1 with a lubrication zone 31, and a lubricant outlet 32. The lubricant is injected into the closed enclosure 1; by centrifugal force, the lubricant is pushed towards the lubrication zone 31, and the excess lubricant is discharged through outlet 32.

[0033] The mechanical parts that make up mechanical system 2 will wear down over time and release particles into the lubricant, forming filings 4. These particles are, for example, iron filings or any other ferromagnetic material. The function of the lubrication circuit 3 is to lubricate the moving parts (typically rotating parts). However, the presence of particles in the lubricant can accelerate the wear of the mechanical parts and / or be an indicator of abnormal wear in the mechanical system.

[0034] Due to the rotation of enclosure 1 and the mechanical system 2, the lubricant will adhere to the inner wall 10 of enclosure 1 in the lubrication zone 31. The metal filings 4 present in the lubricant will also adhere to the inner wall 10 and cannot be removed with the lubricant, as the lubricant inlet 30 and outlet 32 ​​are located on the X-axis. The lubricant remaining in the lubrication zone 31 is therefore always contaminated, and a magnetic plug located after the circuit outlet will not be able to collect it.

[0035] The enclosure 1 according to the invention, visible in Figure 2, has cavities 12 on the periphery of the inner wall 10. These cavities 12 are uniformly distributed over a periphery 120 of said inner wall 10, so as not to create an imbalance during the rotation of the assembly E. In this example, there is only one periphery 120 with cavities 12 shown, but several can be provided along the enclosure 1 without departing from the scope of the present invention. Thus, in this example, cavities 12 can be present on both a cylindrical portion C2 and a conical portion C2 of the enclosure 1.

[0036] Each cavity 12 is surrounded by a conical part 121 with slopes inclined axially and radially towards the cavity and which allows the filings 4 to be directed towards said cavity 12.

[0037] To further facilitate the orientation of the filings 4 towards the cavities 12, the shape of the axial section of the inner wall 10 of the enclosure 1 can be adapted. Thus, in the example of Figure 2, the wall 10 has an oval shape with two cavities 12 arranged at the two vertices of the ellipse. The term "vertex of the ellipse" refers to the two vertices of its major axis. With more than two cavities 12 on a periphery 120, the axial profile can be adapted to the number of cavities 12; thus, for three cavities, a triangular shape is possible, for four, a square shape, and so on.

[0038] In detail A of cavity 12, visible in figure 4, we can see that the oval shape facilitates the guidance of the filings 4 into the cavity 12. In the example of figure 5, the cavity 12 is surrounded by a rim 122. This rim 122 has a conical edge 1221 on the side of the interior of the enclosure 1 and a straight edge 1220 on the side of the cavity 12, in this way the filings 4 can easily enter the cavity 12 but are partially retained in the cavity when the enclosure 1 no longer rotates and the filings 4 are no longer pressed against the bottom of the cavity 12 by the centrifugal force.

[0039] A sensor 5 capable of detecting the passage of ferromagnetic particles 4 is fixed to the outside of the enclosure 1 on a static support, such as a housing (not shown). This sensor may be a variable reluctance inductive sensor. The sensor 5 will emit an electrical signal 50 which will vary when a cavity 12, containing filings, passes in front of said sensor 5. This variation 51, visible in Figure 6, has an amplitude H proportional to the quantity of filings. 4 in cavity 12. In this way we can inform the user when the quantity of filings 4 is critical.

[0040] The sensor 5 is placed opposite a periphery 120 where the cavities 12 are aligned so as to be able to measure the quantity of filings present in said cavities 12. The sensor 5 is set to take into account the number of cavities 12 on the periphery 120 opposite which the sensor 5 is placed, indeed, the higher the number of cavities 12 the lower the concentration of filings per cavity.

[0041] The thickness of the enclosure between the bottom of the cavity 12 and the outer wall 11 will be as thin as possible in order to reduce the air gap between the sensor 5 and the filings 4. The material constituting the bottom of the cavity 12 or the entire enclosure is non-magnetic to have good magnetic permeability.

[0042] We will now describe the measurement procedure. During operation, the mechanical system 2 rotates with the closed enclosure 1. The mechanical parts constituting the mechanical system 2 will wear down with use and release metal filings 4 into the lubrication circuit 3. The centrifugal force created by the rotation will press the metal filings 4 towards the inner wall 10 of the enclosure 1. The inclination of the slopes surrounding the cavities 12, possibly combined with the shape of the inner wall 10, will concentrate the metal filings 4 towards the cavities 12. The sensor 5, positioned on a periphery 120, will measure a variation 51 in the amplitude H of the electrical signal 50 as a cavity 12 passes in front of said sensor 5, allowing the quantity of metal filings 4 in the lubricant to be measured. The amplitude H is proportional to the quantity of metal filings present in a cavity 12.It is possible that some cavities are less filled than others on the periphery 120, a calculator can calculate an average on the number of cavities present on said periphery 120.

[0043] When sensor 5 identifies that the amount of filings is becoming critical, the user can be notified.

[0044] The invention allows the separation of filings from the lubricant by centrifugation and the trapping of the filings.

Claims

DEMANDS

1. Assembly (E) comprising a closed rotating enclosure (1), a mechanical system (2) and a lubrication circuit (3) passing through the rotating enclosure (1), the enclosure comprising an outer wall (11) of revolution with axis X and an inner wall (10) opposite the outer wall (11), characterized in that it comprises a magnetic sensor (5) for detecting filings, that the inner wall (10) comprises n cavities (12) uniformly distributed circumferentially, such that n > 2 and that the sensor (5) is placed opposite a periphery 120 where the cavities (12) are aligned.

2. Assembly (E) according to claim 1, characterized in that the magnetic sensor (5) is a variable reluctance inductive sensor.

3. Assembly (E) according to any one of the preceding claims, characterized in that the cavities (12) are surrounded by a conical shape directed towards each cavity.

4. Assembly (E) according to any one of the preceding claims, characterized in that the cavities (12) have a conical rim.

5. Assembly (E) according to any one of the preceding claims, characterized in that the inner wall (10) has an elliptical cross-section along the X axis and that the cavities (12) are placed at the vertices of the ellipse.

6. Assembly (E) according to any one of the preceding claims, characterized in that the cavities (12) have bottoms of non-magnetic material.

7. Assembly (E) according to any one of the preceding claims, characterized in that the magnetic sensor (5) is fixed.

8. Assembly (E) according to the preceding claim, characterized in that the magnetic sensor (5) is fixed to a housing surrounding the enclosure.

9. Assembly (E) according to any one of the preceding claims, characterized in that the lubricant of the lubrication circuit (3) is oil.

10. A method for measuring the quantity of filings (4) in an assembly (E) according to any one of claims 2 to 6, characterized in that a cavity (12), when passing in front of the inductive sensor (5), creates a signal electrical (50) in said inductive sensor (5) with an amplitude (H) proportional to the quantity of filings (4) in this cavity.

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