HYDRAULIC FITTING EQUIPPED WITH A FILTRATION DEVICE

Abstract

The invention relates to a hydraulic fitting (10) comprising: - a body (11) having at least one chamber (12.1, 12.2), - a reduced-section liquid passage orifice (15) formed in an internal wall (13), and - a filtration device (16) comprising at least one filter insert (17.1, 17.2) including: a filter collar (20) having an external diameter smaller than one diameter of the chamber (12.1, 12.2) so as to define an annular filtration space (21) having a width smaller than one diameter of the reduced-section liquid passage orifice (15), at least one retaining ring (24.1, 24.2) having a diameter adjusted to the diameter of the chamber (12.1, 12.2), and at least one groove (25) allowing the liquid to flow to reach the annular filtration space (21). Figure for the abstract: Figure 8

Description

Title of the invention: HYDRAULIC FITTING EQUIPPED WITH A FILTRATION DEVICE

[0001] The present invention relates to a hydraulic fitting equipped with a filtration device. The invention finds a particularly advantageous, but not exclusive, application in aircraft hydraulic equipment.

[0002] Figure 1 shows a plate 1 associated with one or more hydraulic devices, such as a valve, a check valve, or a hydraulic actuator (not shown). The plate 1 has interface ports 2 on which hydraulic fittings 3 are mounted. The hydraulic fittings 3 may, for this purpose, have a threaded section screwed into an interface port 2. Hydraulic lines (not shown) are each provided with a connection interface designed to cooperate with a corresponding hydraulic fitting 3, in particular by screwing.

[0003] In certain applications, it may be necessary to reduce the speed of a fluid circulating in the pipes, in particular to avoid pressure spike phenomena (water hammer), or cavitation, but also to control the speed of movement of an actuator.

[0004] Flow control is then achieved by means of one or more hydraulic restrictors, generally installed inside the body of the hydraulic equipment. [Fig. 2] shows an example of a hydraulic restrictor consisting of a standard component 4. [Fig. 3] illustrates an example of the installation of hydraulic restrictors 5 inside a plate 1. Depending on the size of the restriction orifice, filter elements 6 (see [Fig. 2]) can be positioned upstream and / or downstream of the orifice to prevent clogging by particles in the fluid. The dimensions of the filter elements 6 can be adapted according to the application.

[0005] Despite the miniaturization of these components, their use imposes constraints on the body design for installing the filtration elements 6, which can lead to an increase in the final dimensions of the plate (and consequently an increase in the overall mass). Furthermore, the manufacturing process can be complex.

[0006] An alternative to using specific components to control fluid flow is to place the restriction within a hydraulic fitting itself. Figure 4 shows a hydraulic fitting 3 equipped with a reduced-section fluid passage 7. Such a device offers both an economic advantage and a reduction in the mass and size of the final product for which a restriction is required.

[0007] Furthermore, integrating the restriction into the fitting 3 offers flexibility when using the same equipment for different applications. For example, a solenoid valve may or may not require a restriction. Thus, depending on the application, for the same mounting plate, it is sufficient to install either a hydraulic fitting with a restriction or a simple fitting without a restriction. This is advantageous for a platform design strategy with a limited number of devices performing the same function.

[0008] Fluids used in hydraulic systems may contain unwanted particulate contamination. The fluid's cleanliness, or its level of contamination, is defined in standard AS4059, which specifies the number of particles per size according to the required contamination class. According to standard AS4941, the use of a restriction with a diameter of less than 1.8 mm in a hydraulic fitting requires that it be protected by a filtration device.

[0009] Depending on the dimensions of the hydraulic fitting, more precisely the inner diameter and its length, it may be possible to integrate a filter 8 marketed by the company LEE having a thimble shape, as shown in [Fig.5].

[0010] Some manufacturers are able to produce custom-made filter components according to given geometric specifications to fit the internal dimensions of a hydraulic fitting. However, for economic reasons, it is more practical to choose existing components from a supplier's catalog. This requires modifying the hydraulic fitting by machining it to adapt to the installation constraints of the selected filter. However, such a solution may not be feasible in cases where additional machining is not possible, particularly to maintain the mechanical strength of the hydraulic fitting.

[0011] If it proves impossible to install a filter from a catalog inside the hydraulic fitting, then this implies adding the filter device inside the hydraulic plate. This solution is conceivable when the flow direction is such that the fluid flow is outward, even though it entails consequences and constraints on the plate design for filter integration. However, when the fluid flow is inward, it becomes necessary to add an interface piece between the pipe and the hydraulic fitting to house the filtration device. This option can be prohibitive, as it may cause difficulties in filter integration and / or be costly.

[0012] The pressure losses caused by filters of this type are generally between 10 bar and 100 bar at a temperature of +20°C under 12.5 L / min for filters with an installation diameter of 6 mm (corresponding, for example, to the inside diameter of a fitting used on a landing gear system), and 150 µm through holes provided for the protection of a 0.5 mm orifice. Such filters are known to cause high pressure losses when viscosity increases, i.e. when the fluid temperature drops.

[0013] The final property determining the choice of a filter is its mechanical resistance to the pressure differential across the filter. Standard filters often require a low pressure differential, generally between 10 bar and 70 bar. However, at very low temperatures (T < -25°C), the fluid viscosity is such that the pressure differential can exceed the filter's mechanical resistance threshold. Similarly, in the case of a high flow rate through the filter, such as a transient flow during the pressurization of a hydraulic line, the resulting pressure differential is likely to damage the filter.

[0014] The invention aims to effectively remedy the aforementioned drawbacks by proposing a hydraulic fitting comprising: - a body comprising at least one chamber, - an internal wall, - a small-section liquid passage opening in the inner wall, and - a filtration device comprising at least one filter insert located inside the chamber, - said filter insert comprising: - a filter collar extending radially from an outer periphery of the filter insert, said filter collar having an outer diameter less than one diameter of the chamber so as to define an annular filtration space having a width less than one diameter of the reduced-section liquid passage orifice, - at least one retaining ring having a diameter adjusted to the diameter of the chamber to allow a tight fit of the filter insert inside the chamber, and - at least one groove made in an axial end face of the filter insert and in the retaining ring so as to allow the liquid to flow to reach the annular filtration space.

[0015] The invention thus makes it possible, by integrating the filtration device into the hydraulic fitting, to limit the constraints of integrating a filter into the hydraulic plate on which the hydraulic fittings are mounted, or to avoid adding an additional part interfacing with the fitting for integrating a filter. The invention also makes it possible to limit machining operations in the fitting to receive the filtration device, in order to preserve the mechanical strength of the hydraulic fitting. The invention makes it possible to limit the pressure drop across the filter with the objective of offering better performance for the same size compared to a filter made of mesh. The invention also makes it possible to filter polluting particles in both directions of liquid flow through the hydraulic fitting.

[0016] According to one embodiment of the invention, said hydraulic fitting comprises a first chamber opening at a first end of the body and a second chamber opening at a second end of the body, and two filter inserts each disposed in a corresponding chamber.

[0017] According to one embodiment of the invention, a width (1) of the annular filtration space is a function of a diameter of the reduced section liquid passage orifice.

[0018] According to one embodiment of the invention, a minimum length of the filtration collar is on the order of 0.3mm in order to minimize pressure losses through the annular filtration space.

[0019] According to one embodiment of the invention, the diameter of the reduced section liquid passage orifice is between 0.5mm and 1.8mm.

[0020] According to one embodiment of the invention, the filter collar (20) has an annular shape with straight end edges.

[0021] According to one embodiment of the invention, the filter collar has an annular shape with inclined end edges.

[0022] According to one embodiment of the invention, the body comprises a threaded section (26) on its outer periphery.

[0023] According to one embodiment of the invention, the body comprises an annular clamping portion.

[0024] According to one embodiment of the invention, the body includes a connection interface with a liquid conduit.

[0025] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0026] [Fig-1] The [Fig. 1], already described, is a partial cross-sectional view of a hydraulic plate equipped with hydraulic fittings according to the prior art;

[0027] [Fig.2] Fig.2, already described, is a cross-sectional view of a hydraulic restriction according to the state of the art;

[0028] [Fig.3] The [Fig.3], already described, is a cross-sectional view of a plate incorporating hydraulic restrictions according to the prior art;

[0029] [Fig.4] Fig.4, already described, is a perspective and partial cross-sectional view of a example of a hydraulic fitting equipped with an integrated restriction orifice according to the prior art;

[0030] [Fig.5] The [Fig.5], already described, shows examples of hydraulic filters according to the prior art that can be integrated into a hydraulic fitting;

[0031] [Fig.6] The [Fig.6] is an exploded perspective view of a hydraulic fitting equipped with filter inserts according to the present invention;

[0032] [Fig.7] The [Fig.7] is a perspective and cross-sectional view of a hydraulic fitting equipped with filter inserts according to the present invention;

[0033] [Fig.8] The [Fig.8] is a longitudinal cross-sectional view of a hydraulic fitting equipped with filter inserts according to the present invention;

[0034] [Fig.9] The [Fig.9] is a detailed cross-sectional view of the Z area circled on the [Fig.8];

[0035] [Fig. 10a] [Fig. 10b] Figures 10a and 10b are schematic cross-sectional representations of two embodiments of a filtration collar of a filter insert according to the invention;

[0036] [Fig.lia] The [Fig.lia] is a graphical representation of a pressure loss expressed in bars as a function of a flow rate, at different temperatures, for a hydraulic fitting according to the prior art;

[0037] [Fig. 11b] The [Fig. 11b] is a graphical representation of a pressure loss expressed in bars as a function of a flow rate, at different temperatures, for a hydraulic fitting according to the invention.

[0038] It should be noted that, in Figures 6 and following, the structural and / or functional elements common to the different embodiments may have the same reference numerals. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0039] Figures 6, 7 and 8 show a hydraulic fitting 10 comprising a body 11 having an axis X. The body 11 has a generally annular shape with axial orientation with respect to the axis X.

[0040] As can be seen in figures 7 and 8, the body 11 has a first chamber 12.1 opening at a first end of the body 11 and a second chamber 12.2 opening at a second end of the body 11. A liquid can pass through the body 11 by passing through the first end and then the second end or conversely by passing through the second end and then the first end.

[0041] Each chamber 12.1, 12.2, defined by an internal bore of the body 11, delimits a hollow cylindrical volume inside the body 11. The first chamber 12.1 has a first diameter corresponding to a first internal diameter DI of the body 11 (see [Fig. 8]). The second chamber 12.2 has a second diameter corresponding to a second internal diameter D2 of the body 11. The first internal diameter DI and the second internal diameter D2 are in this case equal but may alternatively be different from each other.

[0042] An internal wall 13 is arranged between the first chamber 12.1 and the second chamber 12.2. The internal wall 13 extends in a plane perpendicular to the X axis.

[0043] A reduced-section liquid passage orifice 15 is formed in the inner wall 13 to establish fluid communication between the first chamber 12.1 and the second chamber 12.2. Preferably, the diameter of the reduced-section liquid passage orifice 15 is between 0.5 mm and 1.8 mm. Diameters smaller than 0.5 mm are not considered, since such orifices are not used to limit flow rates at hydraulic fittings. Indeed, orifices smaller than this size are generally installed inside the hydraulic equipment.

[0044] Furthermore, a filtration device 16, visible in Figures 6, 7, and 8, comprises a first filter insert 17.1 disposed inside the first chamber 12.1 and a second filter insert 17.2 disposed inside the second chamber 12.2. The filter inserts 17.1 and 17.2 have a generally cylindrical shape. The filter inserts 17.1 and 17.2, with axis XI, are coaxial with respect to the body 11, with axis X.

[0045] Each filter insert 17.1, 17.2 has a filter collar 20 extending radially from an outer periphery of the filter insert 17.1, 17.2. As illustrated in [Fig. 9], the filter collar 20 has an outer diameter D3 smaller than a diameter D1, D2 of the corresponding chamber 12.1, 12.2 so as to define an annular filtration space 21 having a width 1 smaller than a diameter of the reduced-section liquid passage orifice 15. The width 1 of the annular filtration space 21 is measured radially with respect to the X-axis of the body 11. The annular filtration space 21 thus filters particles contained in the fluid that have a dimension larger than this space to protect the orifice 15 of the hydraulic fitting 10.

[0046] Advantageously, a width 1 of the annular filtration space 21 is a function of a diameter of the orifice 15. A width 1 of the annular filtration space 21 is between 1 / 3 and 2 / 3 of a diameter of the orifice 15. It is then possible to define the maximum diameter D3 of the filtration collar to be made according to the internal diameter of the fitting.

[0047] A minimum length L of the filter collar 20 is, for example, on the order of 0.3 mm in order to minimize pressure losses across the annular filtration space 21. The length L is adjusted to allow the filter collar 20 to mechanically withstand the stresses induced by the liquid pressure. "On the order of" means a variation of plus or minus 10% around the stated value.

[0048] As shown in [Fig. 10a], the height h of the filter collar 20 is designed to provide it with good mechanical strength. It is therefore recommended that it be as small as possible. However, in order to limit the pressure drop of the flow between a retaining ring 24.1, 24.2 and the filter collar 20, it is desirable that this height not be too small. In one embodiment, the height h is between 0.5 mm and 1.0 mm.

[0049] According to the embodiment of [Fig. 10a] (and that of Figures 6-9), the filter collar 20 has an annular shape with straight end edges 22. The end edges 22 of the filter collar 20 then extend along a plane perpendicular to the axis XI of the filter insert 17.1, 17.2.

[0050] Alternatively, in the embodiment of [Fig. 10b], the filter collar 20 has an annular shape with inclined end edges 22. The end edges 22 of the filter collar 20 extend along a plane forming a non-zero angle with respect to a plane perpendicular to the axis XI of the insert 17.1, 17.2. Such a configuration makes it possible to give good mechanical strength to the filter collar 20 while increasing its height in order to limit the pressure drop.

[0051] A length L1 measured between the filter collar 20 and the end faces of a filter insert 17.1, 17.2 is between 5mm and 10mm. The filter collar 20 is arranged in a median plane of the filter insert 17.1, 17.2.

[0052] The distance between the orifice 15 and a filter insert 17.1, 17.2 is on the order of 10mm in order to limit the consequences of the jet exiting the orifice 15 on the filter insert 17.1, 17.2, such as erosion.

[0053] In addition, two retaining rings 24.1, 24.2 are each disposed at a corresponding end of a filter insert 17.1, 17.2. Each retaining ring 24.1, 24.2 has a diameter adjusted to the diameter of the chamber 12.1, 12.2 to allow a tight fit of the filter insert 17.1, 17.2 inside the corresponding chamber 12.1, 12.2. Such a configuration prevents the filter insert 17.1, 17.2 from moving along the X axis of the body 11 under a force resulting from the maximum pressure differential (for example 5*107 Pascals) on either side of the hydraulic fitting 10. The retaining rings 24.1, 24.2 also ensure the centering of the filter insert 17.1, 17.2 inside the corresponding chamber 12.1, 12.2.

[0054] At least one groove 25 is formed in each axial end face of the filter insert 17.1, 17.2 and in each corresponding retaining ring 24.1, 24.2 so as to allow the liquid to flow to reach the annular filtration space 21. In the example shown, two cross-shaped grooves 25 are formed in each axial end of the filter insert 17.1, 17.2. Of course, each end face of the filter insert 17.1, 17.2 may have more than two grooves 25 or only one groove 25. The shape (straight or not) and the cross-section (in The U-shaped or rounded shape of a groove 25 may also vary from one application to another. The important thing is to have sufficient contact surface at the retaining ring 24.1, 24.2 so that the insert 17.1, 17.2 is properly held inside the hydraulic fitting 10.

[0055] Furthermore, as can be seen in particular on [Fig. 1], the body 11 has a threaded section 26 on the outer periphery intended to cooperate with a tapped section of a hydraulic plate (not shown).

[0056] The body 11 also includes an annular clamping portion 29. The annular clamping portion 29 extends radially from an external periphery of the body 11. The annular clamping portion 29 has a plurality of clamping faces 30 for cooperating with a clamping tool. The annular clamping portion 29 may, for example, have six clamping faces 30 in such a way as to present a hexagonal shape. Of course, the annular clamping portion 29 may have more or fewer than six clamping faces 30.

[0057] The hydraulic fitting 10 has a connection interface 33 with a liquid line. The connection interface 33 may, in particular, include a threaded section or a tool-free quick-connect device.

[0058] Figures 1a and 11b highlight the reduction in pressure loss achieved with the hydraulic fitting 10 according to the invention. Indeed, [Fig. 1a] is a graphical representation of a pressure loss Pch (expressed in Pascals) as a function of a flow rate Deb (expressed in L / min), at different temperatures, for a hydraulic fitting according to the prior art having an orifice of 1.5 mm and equipped with a filter similar to those of [Fig. 5].

[0059] Figure 11b is a graphical representation of the pressure drop Pch (expressed in Pascals) as a function of the flow rate Deb (expressed in L / min), at different temperatures, for a hydraulic fitting 10 according to the invention having an orifice of 1.5 mm. It can be seen that the hydraulic fitting 10 according to the invention reduces overall pressure losses by a factor of 10 compared to a hydraulic fitting according to the prior art.

[0060] Alternatively, the hydraulic fitting 10 includes a single filter insert 17.1, 17.2.

[0061] Alternatively, a filter insert 17.1, 17.2 can be used with a hydraulic connection 10 comprising a single chamber, such as that shown in [Fig.4].

[0062] Alternatively, a filter insert 17.1, 17.2 comprises a single retaining ring 24.1, 24.2.

[0063] Alternatively, the hydraulic fitting 10 can be used as an interconnector between two liquid lines and in this case comprises a connection interface 33 with a liquid line at each of its ends.

[0064] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0065] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Demands

1. Hydraulic fitting (10) comprising: - a body (11) having at least one chamber (12.1, 12.2), - an inner wall (13), - a reduced-section liquid passage orifice (15) formed in the inner wall (13), and - a filtration device (16), characterized in that said filtration device (16) comprises at least one filter insert (17.1, 17.2) disposed inside the chamber (12.1, 12.2), - said filter insert (17.1, 17.2) comprising: - a filtration collar (20) extending radially from an outer periphery of the filter insert (17.1, 17.2), said filtration collar (20) having an outer diameter smaller than a diameter of the chamber (12.1, 12.2) so as to define an annular filtration space (21) having a width (1) less than a diameter of the reduced section liquid passage orifice (15), - at least one retaining ring (24.1, 24.2) having a diameter adjusted to the diameter of the chamber (12.1, 12.2) to permit tight mounting of the filter insert (17.1, 17.2) inside the chamber (12.1, 12.2), and at least one groove (25) made in an axial end face of the filter insert (17.1, 17.2) and in the retaining ring (24.1, 24.2) so as to permit the liquid to flow to reach the annular filtration space (21).

2. Hydraulic fitting according to claim 1, characterized in that it comprises a first chamber (12.1) opening at a first end of the body (11) and a second chamber (12.2) opening at a second end of the body (11), and two filter inserts (17.1, 17.2) each disposed in a corresponding chamber (12.1, 12.2).

3. Hydraulic fitting according to claim 1 or 2, characterized in that a width (1) of the annular filtration space (21) is a function of a diameter of the reduced section liquid passage orifice (15).

4. Hydraulic fitting according to any one of claims 1 to 3, characterized in that a minimum length (L) of the flange of filtration (20) is on the order of 0.3mm in order to minimize pressure losses through the annular filtration space (21).

5. Hydraulic fitting according to any one of claims 1 to 4, characterized in that a diameter of the reduced section liquid passage orifice (15) is between 0.5mm and 1.8mm.

6. Hydraulic fitting according to any one of claims 1 to 5, characterized in that the filter collar (20) has an annular shape with straight end edges (22).

7. Hydraulic fitting according to any one of claims 1 to 5, characterized in that the filter collar (20) has an annular shape with inclined end edges (22).

8. Hydraulic fitting according to any one of claims 1 to 7, characterized in that the body (11) has a threaded section (26) on its outer periphery.

9. Hydraulic fitting according to any one of claims 1 to 8, characterized in that the body (11) comprises an annular clamping portion (29).

10. Hydraulic fitting according to any one of claims 1 to 9, characterized in that the body (11) has a connection interface (33) with a liquid line.