GENERAL TECHNICAL FIELD AND PRIOR ART

The invention relates to fluid flow restrictor devices and in particular those installed in an engine having a turbine engine of an aircraft.

The flow limiters are conventionally used to limit and therefore control a fluid taken from a main circuit.

Is known from document US 3323550 a flow restrictor consists of a succession of nozzles obtained via grooves oriented sheets. These plates are stacked and bonded together.

One problem with these solutions is that they require multiple parts to be assembled in situ often manually.

In addition, these solutions include retention areas that can cause coking problems in these areas.

PRESENTATION OF THE INVENTION

The invention proposes to overcome at least one of these disadvantages.

To this end, the invention provides a flow restrictor comprising a body comprising a fluid inlet and a fluid outlet; body in which is disposed a fluid conduit of the flow comprising a succession of different sections of rooms in connection with the fluid inlet on the one hand and the output of the other fluid, the conduit being of generally tubular shape, conduit having a bottom with a smooth curve so that the duct does not have any area (s) of retention of the circulating fluid in the conduit.

The invention is advantageously completed by the following characteristics, taken alone or in any technically possible combination.

The limiter is obtained by a manufacturing method for additive manufacturing.

The additive manufacturing process is of the type laser fusion of a powder.

The powder is preferably made of metal, typically Hastelloy X, based on nickel or aluminum type AS7G06.

The conduit is helical.

The conduit is a succession of assemblies each comprising: a cylindrical main chamber having a first section followed by a first secondary chamber and a cylindrical nozzle having a second section followed by a second secondary chamber.

The main chamber, the nozzle, the first and second secondary chambers sharing a common generator such that the bottom of the duct is a regular helical curve.

The first secondary chamber is frusto-conical and is convergent in the direction of flow of the fluid, the second secondary chamber is frusto-conical and diverges in the direction of fluid flow.

The limiter comprises a strainer connection with the fluid inlet disposed downstream of the fluid inlet in the direction of fluid flow.

The limiter comprises a strainer in connection with the fluid disposed upstream exit the fluid outlet in the direction of fluid flow.

The invention also relates to a fuel system of an aircraft turbine engine comprising at least one flow restrictor according to the invention.

Of all the figures, similar elements bear identical references.

PRESENTATION DES FIGURES

Other features, objects and advantages of the invention will become apparent from the following description, which is purely illustrative and not exhaustive, and should be read in conjunction with the accompanying drawings wherein:

Figure 1 illustrates an overview of a flow control valve according to a first embodiment;

2 illustrates an overall view of a flow control valve according to a second embodiment;

- Figure 3 illustrates a view of the inlet of the flow restrictor;

4 illustrates a view of the outlet of the flow restrictor;

5 illustrates a view of the conduit of the flow restrictor;

6 illustrates an overview of a manufacturing device of a flow restrictor.

Of all the figures, similar elements bear identical references.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 2 illustrate a flow restrictor comprising a body 1 with an inlet 2 and a fluid outlet 3 of fluid.

A fluid entering the limiter flows from the inlet 2 to the outlet 3 (arrow F in Figures 1 and 2).

The body 1 is generally cylindrical or conical shape with an outer surface which is not necessarily regular.

The inlet 2 is constituted by a cylinder disposed in the body 1 and is in fluid connection with a conduit 5.

Advantageously, a strainer 4 is disposed directly downstream of the inlet

2 the limiter in the direction of fluid flow (see Figure 3). This is a grid disposed in entry 2, the strainer 4 being in fluid connection with the conduit 5.

The strainer 4 is used to filter the incoming fluid to prevent impurities from entering the duct 5 downstream of the strainer 4.

Alternatively or additionally the strainer 4 can be arranged at the outlet

3 of the limiter (not shown).

The strainer 4 is preferably cone-shaped comprising a plurality of recesses 6 of preferably the same size. Other shapes are however possible.

Furthermore, according to one embodiment (not shown) may be provided in an inlet strainer and strainer limiter at the output of the limiter.

Note, however, that the presence of the strainer 4 is not mandatory.

Line 5 is disposed in the body 1 between the inlet 2 and the outlet 3 (see Figures 1 and 2 and Figure 4) and is generally tubular and has a bottom having a smooth curve so that the conduit 5 does not have area (s) of retention of the fluid circulating in the conduit 5.

The duct 5 comprises a succession of chambers 7, 8, 9, 10 of different sections (see Figure 5).

In particular, there is a nozzle 9 arranged between succession of main rooms 7 of larger cross section, the nozzles 9 are connected with the main chambers 7 by means of second chambers 8, 10 of frustoconical shape, converging shape to the upstream of the nozzle 9 in the direction of flow of fluid and diverging shape to the downstream of the nozzle 9 in the direction of fluid flow.

The succession of nozzles used to provide an equivalent component to a single nozzle of small cross-section, reducing the risk of clogging (pollution particle which can clog small nozzle but passes freely through the larger passage sections) and decreasing sensitivity aeration / cavitation of fluid therethrough. The duct 5 is preferably shaped circular helix (see Figure 5).

The helical shape of the pipe allows more nozzles that if he was right in a given space. The radius of the helix depends on the size of the body 1 and the B section of the conduit 5.

The conduit 5 therefore has a slope that allows the fluid to flow into the limiter. In addition, the limiter is oriented such that gravity (arrow G in Figs 1 and 2) ensure the absence of bottom dead center, that is to say areas of the conduit which could lead to retention of circulating fluid in the conduit.

In particular, the conduit 5 is a succession of units E each comprising: a main chamber 7 having a cylindrical first section, followed by a secondary chamber 8 and a 9-cylindrical nozzle having a second section, followed by a second 10 secondary chamber. The first secondary chamber and the second secondary chamber are frustoconical in shape. As previously described, the first secondary chamber is frustoconical in shape, converging shape to the upstream of the nozzle 9 in the direction of flow of fluid and diverging shape to the downstream of the nozzle 9 in the direction of fluid flow .

In addition, the main chamber, the first and second sub-chambers and the nozzle share a common generator such that the bottom of the duct is a regular helical curve.

The nozzles 9 as is clearly illustrated in Figure 5 are located at the bottom. In addition, among the various rooms there is always a steady slope without change or break it. Thus, leads the bottom 5 is still ongoing.

This way, at the nozzles 9 no retention zone that may cause coking phenomenon in the duct 5.

In relation again to Figure 1, the flow restrictor has an outer diameter D of the duct of between 10 and 20 mm, an inner diameter of between 5 and 10 mm and a height h between 15 and 30 mm.

The limiter described above is preferably obtained by means of a manufacturing process by adding material, additive manufacturing type selective laser melting of a powder.

The powder is preferably made of metal, typically Hastelloy X, based on nickel or aluminum type AS7G06. The powder can also be made of plastic.

The laser, which is a high-energy beam makes it possible to fuse the powder locally in order to build the workpiece layer by layer.

6 illustrates a device for manufacturing by adding additive such selective melting material by laser powder.

The device includes a feed tray 20 of powder which is movable, a 21 spreading the powder bed system causes the powder to a mobile construction platform 22 which rises progressively as the workpiece 23 (the limiter) is manufactured. A 24 powder recycling bin to retrieve the unused powder.

The manufacture is carried out under a controlled atmosphere to allow the laser fusion. To do this, the manufacturing apparatus comprises a system 25 for controlling the atmosphere.

In addition, the manufacturing apparatus comprises a laser source 26 and an optical system 27 that enables to bring the laser beam 22 to the platform construction.

As part of this process (see Figure 6), the piece 23 is made by a succession of layers of tens of microns. A power source 26, laser type, fuses the powder layers one by one selectively according to the 3D model designed.

This process allows to produce parts that can not be achieved by removing material.

By this method, the various elements constituting the limiter does not consist of a complex assembly which in any case would be improved and might cause inaccuracies assemblies and therefore create slope changes in the particular conduit.

Additive manufacturing allows to generate the limiter at progressively by increasing the limiter structure.

Thus, all machining problems of different parts required for the limiter structure are resolved.

CLAIMS

1. Flow limiter comprising a body (1) comprising an inlet (2) and a fluid outlet (3) of fluid; body (1) in which is arranged a duct (5) of fluid flow comprising a succession of different sections chambers in connection with the inlet (2) of fluid on the one hand and the outlet (3) of fluid of Moreover, the conduit (5) being of generally tubular conduit (5) having a bottom with a smooth curve so that the duct (5) does not present a region (s) of retention of the circulating fluid in the duct (5), the conduit (5) being a sequence of sets (E) each comprising: a main chamber (7) having a first cylindrical section followed by a first secondary chamber (8) and a nozzle (9) having a second cylindrical section followed by

2. A flow limiter as claimed in claim 1, wherein the first secondary chamber is frusto-conical and is convergent in the direction of flow of the fluid, the second secondary chamber is frusto-conical and diverges in the direction of fluid flow.

3. Flow limiter according to one of the preceding claims, comprising a strainer (4) in connection with the inlet (2) fluid disposed downstream of the fluid inlet in the direction of fluid flow.

4. Flow limiter according to one of the preceding claims, comprising a strainer (4) in connection with the outlet (3) of fluid disposed upstream of the fluid outlet in the direction of fluid flow.

5. A method of manufacturing a flow control valve according to one of claims 1 to 4, characterized in that said flow limiter is manufactured by additive fabrication.

6. The manufacturing method according to claim 5, wherein the additive manufacturing is of the type laser fusion of a powder.

7. The manufacturing method according to claim 8, wherein the powder is preferably metallic, typically Hastelloy X, based on nickel or aluminum type AS7G06.

8. Fuel system of an aircraft turbine engine comprising at least one speed limiter according to one of claims 1 to 4.