PIPE AND SUCTION UNIT FOR LIQUID PAINT AND MANUFACTURING METHOD OF SUCH A PIPE

Description

[0001] The present invention relates to a liquid paint suction wand, a liquid paint suction assembly comprising such a wand and a method for manufacturing such a wand.

[0002] The invention relates to the field of liquid paint projectors.

[0003] A typical liquid paint sprayer consists of a paint gun supplied with liquid paint by a pneumatic pump. This usually involves a flexible hose of sufficient length, for example, several meters or tens of meters, to allow the operator to easily maneuver the paint gun, while the pump remains stationary, mounted on a cart or a support permanently fixed to the ground, such as a wall or a gantry. The pump draws liquid paint from a paint bucket or tank via a suction tube. The suction tube is fluidly connected to the pump, upstream of the pump, and has a free end that dips into the paint bucket to draw the paint by the pump. More specifically, the pump includes a downward-facing suction inlet, onto which a standard straight metal fitting is mounted.A flexible intermediate tube belonging to the suction wand is connected to this metal fitting. At the other end of the flexible tube, the suction wand includes a metal elbow tube partially immersed in the bucket of liquid paint.

[0004] However, the vertical orientation of the standard fitting is not always ideal given the pump's height, and can lead to significant bending of the flexible intermediate tube. Instead of the straight standard fitting, a standard L-shaped elbow fitting could be used. However, implementing such an L-shaped elbow fitting results in a significant pressure drop, which severely hinders paint pumping and may therefore necessitate a more powerful pump.

[0005] US 4 998 993 A relates to a spraying device including a first rigid tube immersed in a material to be sprayed, a second straight rigid tube connected to a pump, and a flexible tube connecting the two rigid tubes.

[0006] US 8 651 397 B2 describes a paint sprayer, in which a flexible paint suction tube is connected to a pump via an elbow and is immersed in a paint container.

[0007] Unrelated to the technical field of the invention, US 700 378 describes a flexible compensator for plumbing pipes.

[0008] One of the aims of the invention is therefore to address these drawbacks by proposing a new suction wand that avoids imposing too strong a curvature on the intermediate tube while offering a reduced pressure loss for the paint passing through the suction wand, and while being easy to manufacture.

[0009] The invention relates to a liquid paint suction wand according to claim 1.

[0010] A key idea of ​​the invention is to provide the downstream tube with a progressively curved flow path for the liquid paint from the receiving end to the connecting end, thereby preventing excessive pressure loss. The gradual curvature of the downstream tube's path promotes efficient flow of the liquid paint, which typically exhibits poor flow properties, such as relatively high viscosity. The term "path" refers to a geometric curve of the downstream tube, sometimes called the "neutral axis." Thanks to the curvature of the downstream tube, the portion of the path at the receiving end advantageously has a horizontal orientation, or at least an incline relative to the vertical, thus preventing excessive bending of the connected intermediate flexible tube.In addition, the downstream tube is easy to manufacture, since it can advantageously be obtained using a manufacturing process similar to that of the upstream tube, for example including bending a straight raw tube to obtain the downstream elbow and the upstream elbow respectively.

[0011] Other optional and advantageous features of the invention, considered in any technically feasible combination, are defined below: The ratio of the diameter to the radius of curvature is between 0.55 and 0.70, and is preferably equal to 0.625. The diameter is between 20 mm and 30 mm, and is preferably equal to 25 mm; and the radius of curvature is between 31 mm and 50 mm, and is preferably equal to 40 mm. The curved portion of the path defines a central angle with a value between 85° and 95°, the value of the central angle being preferably equal to 90°, so that the cross-section of the receiving end is perpendicular to the cross-section of the connecting end. The pipe further includes a connecting nut for securely attaching the downstream tube to the pump, the connecting nut being mounted at the connecting end, freely pivoting relative to the downstream tube around the path, the connecting nut comprising at least one lug through which the connecting nut can be tightened.The pipe includes an external radial shoulder formed at the connection end and forming a conical surface designed to bear against a complementary connection seat belonging to the pump, when the pipe is connected to the pump, the conical surface being centered on the trajectory and converging along the trajectory in a downstream direction directed away from the receiving end. The upstream and downstream tubes are metallic, preferably stainless steel, and the intermediate tube is made of a flexible material, preferably elastomer.

[0012] The invention also relates to a liquid paint suction assembly for a liquid paint projector, the suction assembly comprising a wand, according to the above, and a pump, the pump being fluidly connected to the connection end of the wand so as to be able to suction liquid paint through the wand.

[0013] The invention also relates to a method for manufacturing a cane according to the foregoing, or a suction assembly according to the foregoing, the method comprising the following steps: supply or manufacture of the upstream tube; supply or manufacture of the intermediate tube; manufacture of the downstream tube from a straight blank tube, the manufacture of the downstream tube including a sub-step of bending the straight blank tube to form the downstream bend of the downstream tube with the radius of curvature, so that the ratio of the diameter to the radius of curvature is less than 1; addition of the strainer to the upstream tube; and assembly of the upstream tube, intermediate tube and downstream tube.

[0014] The following description relates to examples of embodiments of the invention, given for non-limiting purposes, and is made with reference to the accompanying drawings, in which: [ Fig 1 ] There figure 1 is a partial side view, to scale, of a suction wand according to an embodiment of the invention. Fig 2 ] There figure 2 is a partial perspective view of the suction cane of the figure 1 , to scale. [ Fig 3 ] There figure 3 is a partial perspective view of a liquid paint suction assembly, to scale, including the suction wand of the figure 1 and conforming to the invention. Fig 4 ] There figure 4 is a partial longitudinal section, to scale, of the suction assembly of the figure 3 .

[0015] THE figures 1 And 4 show a liquid paint suction assembly, comprising a wand 1 and a suction pump 3, the latter shown partially on the figures 3 And 4The suction assembly forms part of a liquid paint sprayer, which also includes a paint gun (not shown) supplied by the suction pump 3. Pump 3 is preferably driven by a pneumatic motor (not shown), which supplies compressed air at a pressure of, for example, between 1 and 6 bar. Pump 3 advantageously delivers a pressure between 100 and 450 bar, thanks to the compressed air supplied by the motor. Alternatively, depending on the application, pump 3 may deliver a pressure below 100 bar, or even below 20 bar.

[0016] The paint gun is fluidly connected to the outlet of pump 3, that is, downstream of the pump, via a flexible tube whose length, depending on the application, can be between 10 m and 50 m. Pump 3 thus delivers liquid paint to the gun through this flexible tube.

[0017] The paint sprayer can be used for various applications, such as on-site applications like painting a marine vessel, applying exterior plaster to a building, or painting a ceiling. In this case, the dust extraction unit is advantageously mounted on a trolley or other mobile support. Alternatively, the paint sprayer can be used in a factory. In this case, the dust extraction unit can be mounted on a trolley, other mobile support, or on a fixed support such as a wall or a gantry.

[0018] The rod 1 includes a connecting end 6, which is fluidly connected to an inlet end 4 of the pump 3, i.e. the rod 1 is mounted upstream of the pump 3.

[0019] The nozzle 1 includes a suction end 8, opposite the connection end 6, through which the nozzle 1 draws liquid paint from a liquid paint reservoir, such as a bucket or a tank. Depending on the application, the liquid paint reservoir may be a bucket, for example a 20 L (liter) bucket of paint, or a tank, for example a 100 L (liter) tank of paint.

[0020] The suction end 8 is immersed in the liquid paint from the reservoir so that the paint can be drawn through the tube 1 by the action of the pump 3. The paint flows from the suction end 8 to the connection end 6, where it reaches the pump 3. The tube 1 includes a liquid paint filter screen 10, which is carried by the suction end 8. The screen 10 thus performs a coarse filtration of the liquid paint before it enters the tube 1, preventing excessive clogging of the tube 1.

[0021] For the present invention, the upstream direction 100 and the downstream direction 101 are defined with respect to the direction of flow of the liquid paint in the working operation of the suction assembly, that is to say when the gun projects paint discharged by the pump 3 and drawn in via the tube 1. Therefore, in particular, the end 8 is in the upstream direction 100 with respect to the end 6, and the end 6 is in the downstream direction 101 with respect to the end 8.

[0022] The suction tube 1 comprises an upstream tube 12, an intermediate tube 14 and a downstream tube 16, successively fluidly connected in this order from upstream 100 to downstream 101, so as to form a continuous conduit for the paint, from the end 8 to the end 6. The end 8 is formed by the upstream free end of the upstream tube 12. The end 6 is formed by the downstream free end of the downstream tube 16.

[0023] The upstream tube 12 and the downstream tube 16 are rigid, meaning they are more rigid than the intermediate tube 14, which is flexible. For this reason, the upstream tube 12 and downstream tube 16 are made of metal, such as stainless steel, which is not designed to be deformed by hand. Conversely, to be flexible, the intermediate tube 14 is made of a soft material, particularly an elastomer, such as rubber. This flexible material is designed to be reversibly flexed during use, like a garden hose. The pole 1 preferably includes a flexible electrical conductor, such as an electrical wire, electrically connecting the tubes 12 and 16, thus preventing any risk related to the potential flammability of the liquid paint.

[0024] In the figures, tube 14 is shown cut for the sake of simplification, because tube 14 preferably measures a length between 1 m and 2 m.

[0025] From end 8, the upstream tube 12 comprises successively a section 21, preferably straight, an elbow 22, called the "upstream elbow", a section 23, preferably straight and perpendicular to section 21, and a downstream end 24, called the "transmission end", which is fitted, in a paint-tight manner, into an upstream end 31 of the tube 14. The fitting is advantageously maintained by an external clamping ring 25. The upstream tube 12 is thus fluidly connected to the intermediate tube 14, via their respective ends 24 and 31. In use, section 21 is preferably oriented vertically, or is slightly inclined with respect to the vertical, when end 8 is immersed in the liquid paint, while section 23 is oriented horizontally, or slightly inclined with respect to the horizontal.The pipe 1 can then advantageously rest on the edge of the bucket or paint vat by means of part 23, while part 21 dips towards the bottom of the bucket or vat, so that the end 8 is near or against said bottom. The elbow 22 advantageously has an arc shape, the radius of curvature of which is sufficiently large to minimize the pressure loss due to the flow of paint in the pipe 1.

[0026] The upstream tube 12 preferably has an annular cross-section along its entire length. The upstream tube 12, in particular its inner wall guiding the liquid paint, thus delimits a succession of substantially discoidal cross-sections of constant diameter Ds12 for the liquid paint, from end 8 to end 24. Each cross-section of the tube 12 defines a cross-section center, which is the center of the discoidal shape of the cross-section in question. The union of the cross-section centers constitutes a trajectory T12 of the tube 12, shown in dashed lines on the figure 1 Parts 21 and 23 of tube 12 extend along respective straight sections of trajectory T12. Bend 22 extends along a curved section of trajectory T12. Trajectory T12 is advantageously planar, in the plane of the figure 1 The diameter Ds12 is sometimes referred to as the "inner diameter" of tube 12.

[0027] For the upstream tube 12, the curved part of the trajectory T12 is advantageously in the shape of a planar circular arc, in the plane of the figure 1 and having a radius of curvature Rc12, the ratio of the diameter Ds12 to the radius of curvature Rc12 being less than 1, or even less than 0.5. The pressure loss is therefore minimized during the circulation of the liquid paint in the tube 12.

[0028] Preferably, the curved part of the trajectory T12 defines a central angle θ12 of 90°, or otherwise advantageously between 85° and 95°. When the value of the central angle θ12 is equal to 90°, the passage section formed by the end 8 is perpendicular to the passage section formed by the end 24. In other words, the two straight parts of the trajectory T12 are perpendicular.

[0029] Preferably, the intermediate tube 14 has an annular cross-section along its entire length. The tube 14 thus delimits a succession of substantially discoidal cross-sections with a diameter Ds14 close to, or equal to, the diameter Ds12. Each cross-section of the tube 14 defines a cross-section center, which is the center of the discoidal shape of the cross-section in question. The union of the cross-section centers constitutes a trajectory T14 of the tube 14, shown in dashed lines on the figure 1 Tubes 12 and 14 are advantageously shaped and assembled so that the trajectory T14 extends the trajectory T12. The diameter Ds14 is sometimes called the "inner diameter" of tube 14.

[0030] From end 6, the downstream tube 16 comprises successively a section 41, preferably straight, an elbow 42, called the "downstream elbow", a section 43, preferably straight and perpendicular to section 41, and an upstream end 44, called the "receiving end", which is fitted, in a paint-tight manner, into a downstream end 32 of the tube 14. The fitting is advantageously maintained by an external clamping ring 26. The downstream tube 16 is thus fluidly connected to the intermediate tube 14, via their respective ends 44 and 32. In operation, section 41 is preferably oriented vertically, or is slightly inclined with respect to the vertical, when end 6 is connected to the pump 3, while section 43 is oriented horizontally, or slightly inclined with respect to the horizontal.The tube 14 is then oriented horizontally in the vicinity of its end 32, which avoids giving it too much bend if the height of the space available under the pump is low, or if the edge of the bucket or paint tank is particularly high compared to the bottom of the pump 3.

[0031] Preferably, as shown on the figure 4 For end 44, each tube 12 and 16 includes, at its respective end 24 or 44, external radial ribs to improve the reliability of the connections with tube 14. Preferably, as shown in the figure 4 for the end 44, each tube 12 and 16 includes, at its respective end 24 or 44, an external shoulder against which the end 31 or 32 concerned comes to rest axially, which makes it possible to ensure the precise axial positioning of the tube 14 on each tube 12 and 16 when fitted.

[0032] The elbow 42 advantageously has an arc shape, the radius of curvature of which is sufficiently high to minimize the pressure loss related to the circulation of the paint in the can 1.

[0033] The downstream tube 16 preferably has an annular cross-section along its entire length. The downstream tube 16, in particular its inner wall guiding the liquid paint, thus delimits a succession of transverse passage sections S16 for the liquid paint, from end 44 to end 6. Each passage section of the tube 16 defines a passage center C16, which is the center of the discoid shape of the passage section in question. The union of the passage centers constitutes a trajectory T16 of the tube 16, shown in dashed lines, notably on the figure 4 As shown on the figure 4 The sections 41 and 43 of the tube 16 extend along respective straight portions of the trajectory T16. The bend 42 extends along a curved portion 49 of the trajectory T16. At least for the portion 49, and preferably also for the entire length of the trajectory T16, the sections S16 are substantially discoidal and of constant diameter Ds16. The trajectory T16 is advantageously planar, in the plane of the figure 4 The Ds16 diameter is sometimes referred to as the "inner diameter" of the 16 tube.

[0034] A cross-sectional view AA of tube 16 is shown on the figure 4 , to identify one of the passage sections S16, the diameter Ds16, the center C16 of this passage section S16.

[0035] For the purposes of this invention, "substantially discoidal" means that the relevant passage section may be either exactly discoidal or have a slightly flattened, elliptical, or slightly deformed discoidal shape, for example, ovate. In particular, the passage section may not be strictly discoidal if it is located on the curved portion 49 of the trajectory T16. In this case, the diameter Ds16 designates the largest diameter of the passage section.

[0036] For the downstream tube 16, the curved part 49 of the trajectory T16 is advantageously in the shape of a planar circular arc, in the plane of the figure 4 and having a radius of curvature Rc16. In this example, the ratio of the diameter Ds16 to the radius of curvature Rc16 is 0.625, with the diameter Ds16 being 25 mm and the radius of curvature Rc16 being 40 mm. Preferably, the diameter Ds16 is between 20 and 30 mm, while the radius of curvature Rc16 is between 31 and 50 mm. Preferably, the ratio of the diameter Ds16 to the radius of curvature Rc16 is between 0.55 and 0.70. More generally, it is expected that the ratio of the diameter Ds16 to the radius of curvature Rc16 is less than 1, i.e. that (Ds16 / Rc16) < 1. The pressure loss is therefore minimized during the circulation of the liquid paint in the tube 16, as explained above.

[0037] Preferably, the curved portion 49 of the trajectory T16 defines a central angle θ16 of 90°, or otherwise advantageously of a value between 85° and 95°. When the value of the central angle θ16 is equal to 90°, the passage section S16 formed by the end 44 is perpendicular to the passage section S16 formed by the end 6. In other words, the two straight portions of the trajectory T16 are then perpendicular.

[0038] Tubes 14 and 16 are advantageously shaped and assembled so that the trajectory T16 extends the trajectory T14.

[0039] Preferably, the diameters Ds12 and Ds16 are equal to each other, and are preferably equal, at least approximately, to the diameter Ds14. Preferably, tubes 12 and 16 are manufactured from the same raw tube, cut and worked to form tubes 12 and 16.

[0040] Preferably, as shown on the figure 4 The suction tube 1 includes an external radial shoulder 51 formed at the end 6. The external radial shoulder 51 carries a conical surface 52. The conical surface 52 is centered and coaxial with the straight part of the trajectory T16 located at the height of the end 6. The conical surface 52 converges along the trajectory T16 downstream, i.e. here, towards the pump 3.

[0041] When the suction tube 1 is connected to the suction pump 3, as is the case on the figure 4 The conical surface 52 is designed to bear against a connection seat 61 of the pump 3, which is complementary to this conical surface 52. Preferably, at end 4, the seat 61 has a tubular shape, with an annular cross-section, and a diameter larger than that of the tube 16. Thus, the conical surface 52 bears against the annular seat 61, so as to automatically center the tube 16 on the inlet end 4 of the pump 3. The contact of the conical surface 52 against the seat 61 is made over the entire circumference of the conical surface 52, so that a seal against liquid paint is ensured for this connection, by axial clamping of the conical surface 52 against the seat 61.

[0042] Preferably, the connecting seat 61 is chamfered on the inside so as to be of complementary conical shape with the conical surface 52.

[0043] To ensure this axial clamping and thus smoothly connect the tube 16 to the pump 3, and to ensure that the tube 16 is fixed relative to the end 4 of the pump 3, the rod 1 advantageously includes a connecting nut 71. The connecting nut 71 is mounted at the end 6 of the tube 16, and is freely pivotable relative to the tube 16, around the straight portion of the path T16. The nut 71 includes an internal shoulder 72 which axially abuts against the shoulder 51, so that the nut cannot be removed from the tube 16 if the nut 71 is pulled in the downstream direction. Furthermore, the nut 71 is capable of applying a clamping force in the downstream direction, bearing axially against the shoulder 51 via its shoulder 72.

[0044] The nut 71 includes an internal thread 73, extending downstream of the shoulder 72. The nut 71 thus has a general skirt shape which, on the figure 4, is turned upwards. The end 4 has, downstream from the seat 61, an external thread 63 complementary to the internal thread 73. Thus, the nut 71 can be screwed onto the end 4 by screwing the thread 73 with the thread 63, this screwing resulting in contact and axial clamping of the conical surface 52 against the seat 61.

[0045] Advantageously, the nut 71 includes two lugs 74, each forming an external radial protrusion. These lugs are evenly spaced around the circumference of the nut 71. These lugs 74 allow the nut 71 to be tightened and loosened without tools. Indeed, the operator using the liquid paint sprayer may not necessarily have such tools, yet they may need to remove the nozzle 1 from the pump 3 for cleaning, nozzle replacement, unclogging, or color changes. In particular, if the nut 71 is tightened and accidentally clogged with paint, it can be loosened by striking the lugs 74 with a mallet, whereas this would have been considerably more difficult if the nut had been a hex nut.

[0046] Alternatively, nut 71 has a number of ears 74 different from two.

[0047] Nut 71, for example, may have a single lug 74 while still offering the advantages described above, namely allowing the nut 71 to be tightened and loosened without tools. In particular, if nut 71 is tightened and accidentally clogged with paint, it is possible to loosen the nut by striking the lug 74 with a mallet, whereas this would have been significantly more difficult with another nut.

[0048] The suction wand 1 and the suction assembly defined above are preferably manufactured using a manufacturing process defined below.

[0049] In this manufacturing process, manufacturing steps for the upstream tube 12 and the downstream tube 16 are implemented.

[0050] To manufacture these two tubes 12 and 16, it is advantageous to start with the same straight raw tube, or with two identical raw tubes, whose cross-sectional diameter is equal to the diameters Ds12 and Ds16, which are themselves equal to each other. For each of the tubes 12 and 16, the upstream bend 22 and the downstream bend 42 are made by bending the straight tube, in order to impart a radius of curvature Rc12 or Rc16, depending on the tube 12 or 16 concerned, said radius of curvature Rc12 or Rc16 being sufficiently large compared to the cross-sectional diameter, either Ds12 or Ds16, in order to verify that (Ds12 / Rc12)<1 and (Ds16 / Rc16)<1.

[0051] It is therefore particularly easy to manufacture the cane 1, since the two tubes 12 and 16 can be obtained with a similar bending process, preferably from the same raw profiles.

[0052] Alternatively, the upstream tube 12 can be supplied rather than manufactured. Alternatively, the upstream tube 12 is manufactured from a different blank than that used to manufacture the tube 16. Alternatively, the intermediate tube 14 can be manufactured rather than supplied.

[0053] The manufacturing process also includes a step of adding the strainer 10 to the tube 12. The manufacturing process also includes a step of forming or adding the shoulder 51 to the tube 16.

[0054] Once tubes 12, 14 and 16 have been obtained, the process includes a step of assembling said tubes 12, 14 and 16 together, preferably by fitting as explained above.

[0055] Any feature described above for one embodiment or variant may be implemented in other embodiments and variants described above, insofar as technically possible.

Claims

1. A liquid paint suction rod (1), designed to be connected to a liquid paint suction pump (3) and comprising: - a flexible intermediate tube (14); and - a rigid downstream tube (16), which comprises: ∘ a connecting end (6), designed to be fluidly connected to the pump (3), ∘ a receiving end (44), and ∘ a downstream elbow (42), between the receiving end (44) and the connecting end (6), wherein the downstream tube (16) delimits a series of transverse passage sections (S16) for liquid paint, from the receiving end (44) to the connecting end (6), each passage section (S16) defining a passage section (S16) center (C16), the union of the passage section (S16) centers (C16) constituting a trajectory (T16) of the downstream tube (16), the downstream elbow (42) extending along a curved part (49) of the trajectory (T16), along which the passage sections (S16) have a substantially discoid shape and have a preferably constant diameter (Ds16), the rod (1) being characterized in that: - the rod (1) comprises a rigid upstream tube (12), which comprises a suction end (8) and an upstream elbow (22), the suction end (8) being designed to be submerged in the liquid paint in order to suction liquid paint through the rod (1), the intermediate tube (14) fluidly connecting the upstream tube (12) to the receiving end (44); - the rod (1) further comprises a liquid paint filtering strainer (10), borne by the suction end (8); and - the curved part (49) of the trajectory (T16) is in the shape of a planar arc of circle, having a curve radius (Rc16), the ratio of the diameter (Ds16) to the curve radius (Rc16) being less than 1.

2. The rod (1) according to claim 1, wherein the ratio of the diameter (Ds16) to the curve radius (Rc16) is between 0.55 and 0.70, and is preferably equal to 0.625.

3. The rod part (1) according to any one of the preceding claims, wherein: - the diameter (Ds16) is between 20 mm and 30 mm, and is preferably equal to 25 mm; and - the curve radius (Rc16) is between 31 mm and 50 mm, and is preferably equal to 40 mm.

4. The rod (1) according to any one of the preceding claims, wherein the curved part (49) of the trajectory (T16) defines a center angle (θ16) with a value of between 85° and 95°, the value of the center angle (θ16) preferably being equal to 90° such that the passage section (S16) of the receiving end (44) is perpendicular to the passage section (S16) of the connecting end (6).

5. The rod (1) according to any one of the preceding claims, further comprising a connecting nut (71) to securely attach the downstream tube (16) to the pump (3), the connecting nut (71) being mounted at the connecting end (6), freely pivoting relative to the downstream tube (16) around the trajectory (T16), the connecting nut (71) comprising at least one lug (74) by means of which the tightening of the connecting nut (71) can be done.

6. The rod (1) according to any one of the preceding claims, the rod (1) comprising an outer radial shoulder (51) formed at the connecting end (6) and forming a conical surface (52) designed to be able to be received by bearing against a complementary connecting seat (61) belonging to the pump (3), when the rod (1) is connected to the pump (3), the conical surface (52) being centered on the trajectory (T16) and converging along the trajectory (T16) in a downstream direction (101) oriented away from the receiving end (44).

7. The rod (1) according to any one of the preceding claims, wherein the upstream tube (12) and the downstream tube (16) are made from metal, preferably stainless steel, and the intermediate tube (14) from a flexible material, preferably elastomer.

8. A liquid paint suction assembly for a liquid paint sprayer, the suction assembly comprising a rod (1), according to any one of the preceding claims, and a pump (3), the pump (3) being fluidly connected to the connecting end (6) of the rod (1) so as to be able to suction liquid paint by means of the rod (1).

9. A method for manufacturing a rod (1) according to any one of claims 1 to 7, or a suction assembly according to claim 8, the method comprising the following steps: - providing or manufacturing the upstream tube (12); - providing or manufacturing the intermediate tube (14); - manufacturing the downstream tube (16) from a raw rectilinear tube, the manufacturing of the downstream tube (16) including a step for bending the raw rectilinear tube in order to form the downstream elbow (42) of the downstream tube (16) with the curve radius (Rc16), such that the ratio of the diameter (Ds16) to the curve radius (Rc16) is less than 1; - adding of the strainer (10) to the upstream tube (12); and - once the tubes (12, 14, 16) are obtained, assembling the upstream tube (12), the intermediate tube (14) and the downstream tube (16).