EP3639930A1 - Method of spraying a fluid - Google Patents

Abstract

The invention relates to a method of spraying a fluid (F) by an installation (10) for spraying the fluid (F) comprising a pump (12), a sprayer (13) suitable for spraying the fluid (F) and a fluid circulation conduit (15) suitable for conducting the fluid (F) from the pump (12) to the sprayer (13), an upstream and a downstream being defined for the fluid circulation conduit (15) , the fluid (15) flowing from upstream to downstream when the fluid (F) crosses the conduit (15) from the pump (12) to the sprayer (13).

The method comprises a step of circulating, in the conduit (15), a scraper from upstream to downstream to push back to the sprayer (13) the fluid (F) contained in the circulation conduit (15) , the fluid (F) repelled by the scraper being projected by the sprayer (13).

Description

The present invention relates to a method of spraying a fluid.

Fluid spraying installations are used in many applications, in particular for spraying paints or other coating products. In these installations, the fluid to be sprayed circulates in a conduit from a pumping device comprising in particular a shade changer block to a spraying device such as a sprayer.

The sprayer is generally mobile, for example mounted on a robotic arm or even manipulated by an operator, in order to allow the installation to project the fluid onto surfaces of objects, structures or installations which are liable to vary , or whose surface is large and therefore requires a displacement of the sprayer so that the entire surface is covered with the fluid to be sprayed. Since the pumps and the color changing blocks supplying the conduit with one or more fluids to be sprayed are heavy and have large dimensions, it is undesirable that these elements be mounted with the sprayer and mobile with it. Consequently, the conduit in which the fluid circulates between the pumping device and the sprayer has a considerable length, frequently greater than or equal to one meter.

Thus, at the end of the projection of the fluid, a substantial amount of fluid is present in the conduit. Different techniques are then used to remove, recover or make the best use of this remaining fluid, in particular when another fluid must then be sprayed by the same installation.

In some cases, the fluid present in the conduit is propelled to the sprayer by injection of solvent into the conduit. However, part of the fluid then remains on the internal walls of the conduit, the solvent then progressing in the radially central part of the conduit, surrounded by the fluid remaining on the walls. Consequently, only part of the fluid present in the duct is effectively projected.

In some installations, a scraper is used to clean the duct and for example bring the fluid back into the pumping device so that it can be reused. However, this implies a significant loss of time between two projections since the scraper must be introduced into the conduit, push the fluid back to the pumping device and then return to the point where the scraper was introduced in order to be removed from the conduit.

The objective of the invention is to propose a spraying process which is rapid and which has a better yield in terms of quantity of fluid consumed.

To this end, the subject of the invention is a process for spraying a fluid by a fluid spraying installation comprising a pump, a sprayer capable of spraying the fluid and a fluid circulation pipe suitable for driving the fluid from the pump to the sprayer, an upstream and a downstream being defined for the fluid circulation duct, the fluid circulating from upstream to downstream when the fluid crosses the duct from the pump to the sprayer, the method comprising a stage of circulation, in the duct, of a scraper from upstream to downstream to push back to the sprayer the fluid contained in the circulation duct, the fluid repelled by the scraper being projected by the sprayer.

• le conduit présente un diamètre interne, le racleur présentant un diamètre externe, le diamètre externe ayant une première valeur, une différence entre le diamètre interne du conduit et la première valeur de diamètre externe du racleur étant supérieure ou égale à 100 micromètres, de préférence supérieure ou égale à 200 micromètres.
• le conduit de circulation comprend au moins une portion hélicoïdale.
• le fluide est une peinture comprenant des particules électriquement conductrices, notamment des particules d'aluminium.
• le procédé comprend une première étape de projection du fluide, le fluide étant injecté dans le conduit de circulation par la pompe lors de la première étape de projection, la première étape de projection comprenant la détermination d'un premier volume de fluide projeté depuis le début de la première étape de projection, la première étape de projection étant mise en oeuvre jusqu'à ce qu'une différence entre le volume total et le premier volume est égale à un deuxième volume de fluide contenu dans le conduit de circulation, l'étape de circulation étant mise en oeuvre postérieurement à la première étape de projection.
• le procédé comprend une deuxième étape de projection d'un fluide différent du fluide projeté pendant la première étape de projection, la deuxième étape de projection étant mise en oeuvre postérieurement à l'étape de circulation.
• le fluide projeté pendant la première étape de projection présente une première teinte, le fluide projeté pendant la deuxième étape de projection présentant une deuxième teinte différente de la première teinte.
• le procédé comprend, en outre, une étape de retour comprenant l'injection d'un solvant dans le conduit de circulation en aval du racleur pour déplacer le racleur vers l'amont dans le conduit de circulation.
• le procédé est mis en oeuvre par une installation comprenant, en outre, un injecteur propre à injecter un liquide dans le conduit de circulation, l'étape de circulation comprenant l'injection du liquide dans le conduit de circulation en amont du racleur pour propulser le racleur vers l'aval.
• l'injecteur comprend un cylindre contenant le liquide et un piston accueilli dans le cylindre, l'étape de circulation comprenant le déplacement du piston dans le cylindre pour injecter dans le conduit de circulation le liquide contenu dans le cylindre.

According to other advantageous but not compulsory aspects of the invention, the fluid spraying method comprises one or more of the following characteristics, taken alone or in any technically possible combination:

• the conduit has an internal diameter, the scraper having an external diameter, the external diameter having a first value, a difference between the internal diameter of the conduit and the first value of the external diameter of the scraper being greater than or equal to 100 micrometers, preferably greater or equal to 200 micrometers.
• the circulation duct comprises at least one helical portion.
• the fluid is a paint comprising electrically conductive particles, in particular aluminum particles.
• the method comprises a first step of spraying the fluid, the fluid being injected into the circulation duct by the pump during the first step of spraying, the first step of spraying comprising determining a first volume of fluid sprayed from the start of the first projection step, the first projection step being implemented until a difference between the total volume and the first volume is equal to a second volume of fluid contained in the circulation duct, the step traffic being implemented after the first projection step.
• the method comprises a second step of spraying a fluid different from the fluid sprayed during the first spraying step, the second spraying step being implemented after the circulation step.
• the fluid sprayed during the first spraying step has a first shade, the fluid sprayed during the second spraying step having a second shade different from the first shade.
• the method further comprises a return step comprising injecting a solvent into the circulation duct downstream of the scraper to move the scraper upstream in the circulation duct.
• the method is implemented by an installation further comprising an injector capable of injecting a liquid into the circulation duct, the circulation step comprising injecting the liquid into the circulation duct upstream of the scraper to propel the scraper downstream.
• the injector comprises a cylinder containing the liquid and a piston received in the cylinder, the circulation step comprising moving the piston in the cylinder to inject the liquid contained in the cylinder into the circulation conduit.

The invention also relates to an installation for spraying a fluid comprising a sprayer capable of spraying the fluid, a pump and a fluid circulation conduit, the pump being capable of injecting the fluid into the circulation conduit, the conduit being circulated configured to guide the fluid from the pump to the sprayer, the installation further comprising an injector configured to inject a liquid into the circulation duct, the injector comprising a cylinder, a piston received in the cylinder and a actuator capable of moving the piston in the cylinder from a first position to a second position, the injector being configured so that the displacement of the piston in the cylinder towards its second position causes the injection of the liquid into the circulation duct.

• un amont et un aval sont définis pour le conduit de circulation, le fluide circulant de l'amont vers l'aval lorsque le fluide est guidé par le conduit de circulation depuis la pompe jusqu'au pulvérisateur, l'injecteur étant configuré pour injecter le liquide dans une extrémité amont du conduit de circulation.
• l'installation comprend, en outre, un racleur propre à circuler dans le conduit de circulation pour repousser devant lui le fluide contenu dans le conduit de circulation.
• le conduit présente un diamètre interne, le racleur présentant un diamètre externe, le diamètre externe ayant une première valeur, une différence entre le diamètre interne du conduit et la première valeur de diamètre externe du racleur étant supérieure ou égale à 100 micromètres, de préférence supérieure ou égale à 200 micromètres.

According to advantageous but not compulsory aspects of the invention, the installation comprises one or more of the following characteristics, taken in isolation or according to all technically possible combinations:

• an upstream and a downstream are defined for the circulation duct, the fluid circulating from upstream to downstream when the fluid is guided by the circulation duct from the pump to the sprayer, the injector being configured to inject the liquid in an upstream end of the circulation duct.
• the installation further comprises a scraper adapted to circulate in the circulation duct to repel before it the fluid contained in the circulation duct.
• the conduit has an internal diameter, the scraper having an external diameter, the external diameter having a first value, a difference between the internal diameter of the conduit and the first value of the external diameter of the scraper being greater than or equal to 100 micrometers, preferably greater or equal to 200 micrometers.

• la figure 1 est une représentation schématique d'un premier exemple d'installation de projection de fluide comprenant un conduit de circulation de fluide et un racleur,
• la figure 2 est une représentation schématique partielle en coupe du premier exemple d'installation de projection de fluide,
• la figure 3 est une représentation schématique partielle en coupe d'un deuxième exemple d'installation de projection de fluide,
• la figure 4 est une représentation schématique partielle en coupe d'un troisième exemple d'installation de projection de fluide comprenant un conduit, une pression dans le conduit étant égale à une première valeur,
• la figure 5 est une représentation schématique partielle en coupe de l'installation de la figure 4, la pression dans le conduit étant égale à une deuxième valeur strictement supérieure à la première valeur,
• la figure 6 est une représentation schématique partielle en coupe d'une variante du troisième exemple d'installation de projection de fluide, la pression dans le conduit étant égale à la deuxième valeur, et
• la figure 7 est une représentation schématique d'un autre exemple d'installation de projection de fluide.

Characteristics and advantages of the invention will appear on reading the description which follows, given solely by way of nonlimiting example, and made with reference to the appended drawings, in which:

• the figure 1 is a schematic representation of a first example of a fluid spraying installation comprising a fluid circulation duct and a scraper,
• the figure 2 is a partial schematic representation in section of the first example of a fluid projection installation,
• the figure 3 is a partial schematic representation in section of a second example of a fluid projection installation,
• the figure 4 is a partial schematic representation in section of a third example of a fluid spraying installation comprising a duct, a pressure in the duct being equal to a first value,
• the figure 5 is a partial schematic representation in section of the installation of the figure 4 , the pressure in the conduit being equal to a second value strictly greater than the first value,
• the figure 6 is a partial schematic representation in section of a variant of the third example of a fluid spraying installation, the pressure in the duct being equal to the second value, and
• the figure 7 is a schematic representation of another example of a fluid projection installation.

A first example of a fluid projection installation 10 is shown in the figure 1 .

The installation 10 is configured to project a first fluid F.

The installation 10 comprises, for example, a shade changer block 11, a pump 12 and a member 13 for projecting the first fluid F such as a paint spray gun or even a sprayer.

The installation 10 further comprises a conduit 15 for circulating fluid F, a scraper 20 and at least one injector 21.

The shade changer block 11, the pump 12, the circulation duct 15 and the projection member 13 jointly form a circuit 16 for circulation of the first fluid F. The circuit 16 is in particular suitable for conducting the first fluid F from the block shade changer 11 to the projection member 13.

The first fluid F is, for example, a liquid, such as a paint or other coating product.

According to one embodiment, the first fluid F comprises a set of electrically conductive particles, in particular metallic particles, such as aluminum particles.

The shade changer block 11 is configured to supply the pump 12 with the first fluid F. In particular, the shade changer block 11 is configured to supply the pump 12 with a plurality of first fluids F, and for switching the supply of the pump 12 from a first fluid F to another first fluid F.

In particular, each of the first fluids F with which the shade changer block 11 is capable of supplying the pump 12 is, for example, a paint having a shade different from the shades of the other first fluids F.

The pump 12 is suitable for injecting into the circulation conduit 15 a flow rate of the first fluid F received from the shade changer block 11. For example, the pump 12 is connected to the circulation conduit 15 by a valve 14.

The pump 12 is, for example, a gear pump.

The projection member 13 is suitable for receiving the first fluid F and for projecting the first fluid F.

For example, the projection member 13 comprises a valve 22 and a sprayer head 23.

The projection member 13 is, for example, mounted on a movable arm capable of orienting the projection member 13 in the direction of an object on which the first fluid F is to be projected.

The valve 22 is configured to connect the circulation conduit 15 to the sprayer head 23, and to switch between an open configuration allowing the passage of first fluid F from the circulation conduit 15 to the sprayer head 23 and a closed configuration preventing this passage.

The sprayer head 23 is configured to spray the first fluid F received from the valve 22.

The fluid circulation conduit 15 is configured to conduct the first fluid F received from the valve 14 to the projection member 13.

The fluid circulation conduit 15 is cylindrical. For example, the fluid circulation conduit 15 has a circular section and extends along a first axis A1.

According to one embodiment, the fluid circulation conduit 15 is rectilinear. As a variant, the fluid circulation conduit 15 is a curved conduit for which the first axis A1 is defined locally at any point of the fluid circulation conduit 15 as being perpendicular to a plane in which the section of the fluid circulation conduit 15 is circular.

The fluid circulation conduit 15 has an internal surface 25 delimiting a lumen of the fluid circulation conduit 15 in a plane perpendicular to the first axis A1.

The fluid circulation duct 15 also has an external surface 27 which is visible on the figure 3 . In order to simplify the figures 1 , 2 and 4 to 7 , the external surface 27 is only shown on the figure 3 .

There is defined an upstream and a downstream for the circulation duct 15. The upstream and downstream are defined in that, during the projection of the first fluid F, the first fluid F circulates in the circulation duct 15 from the 'upstream downstream.

For example, the pump is configured to inject the first fluid F at an upstream end 15A of the circulation duct 15 while a downstream end 15B of the circulation duct 15 is connected to the sprayer to allow the first fluid F to flow from the upstream downstream from the pump to the sprayer through the circulation duct 15. This is shown in the figure 1 by an arrow 26.

According to the example shown on the figure 1 , the fluid circulation conduit 15 comprises a first portion 28 and a second portion 29.

The circulation duct 15 has a length greater than or equal to 50 centimeters, for example greater than or equal to one meter. According to one embodiment, each of the first portion 28 and of the second portion 29 has a length greater than or equal to one meter.

The first portion 28 is arranged upstream of the second portion 29.

The first portion 28 is, for example, configured to deform so as to follow the movement of the projection member 13.

The second portion 28 is, for example, received in the projection member 13 and movable with it.

The second portion 29 is, for example, helical.

An internal diameter Di is defined for the fluid circulation conduit 15. The internal diameter Di is measured in a plane perpendicular to the first axis A1 between two diametrically opposite points on the internal surface 25.

The internal diameter Di is, for example, between 3.8 and 6.2 mm. It should be noted that the internal diameter Di of the circulation duct 15 is liable to vary.

The fluid circulation conduit 15 is, for example, made of a metallic material. Alternatively, the fluid circulation conduit 15 is made of a polymeric material.

The scraper 20 is configured to circulate in the fluid circulation conduit 15 in order to push in front of it the first fluid F present on the internal surface 25 during its movement in the fluid circulation conduit 15. In particular, the scraper 20 is configured to clean the internal surface 25, i.e. to leave behind an internal surface 25 covered with a quantity of first fluid F less than the quantity covering the internal surface 25 before the scraper 20 passes, for example to remove all of the first fluid F covering the internal surface 25 of the portions of the conduit 15 in which the scraper 20 circulates.

It is understood by "pushing back in front of it" that the scraper 20, circulating in a direction in the fluid circulation conduit 15, imposes a movement in this direction on the first fluid F which is received in the portion of the conduit 15 in the direction of which the scraper 20 moves. For example, a scraper 20 moving from upstream to downstream imposes on the first fluid F located downstream of the scraper 20 a movement downstream.

The scraper 20 extends along a second axis A2.

The scraper 20 comprises at least one portion having a circular section in a plane perpendicular to the second axis A2.

According to the example of the figure 2 , the scraper 20 is substantially cylindrical and has a symmetry of revolution around the second axis A2.

The scraper 20 is designed to circulate in the circulation duct 15 when the scraper 20 is received in the lumen of the circulation duct 15 and that the first axis A1 is coincident with the second axis A2, as shown in the figure 2 .

The scraper 20 has an external diameter. The external diameter is the external diameter of the portion of the scraper 20 having the largest external diameter in a plane perpendicular to the second axis A2.

The external diameter has a first value De1.

The first value De1 is strictly less than the internal diameter Di of the circulation duct 15.

A difference between the internal diameter Di of the circulation conduit 15 and the first value De1 is greater than or equal to 100 micrometers (μm). For example, the difference is greater than or equal to 200 µm.

The difference is less than or equal to 300 µm.

According to one embodiment, the difference is equal to 200 μm.

The scraper 20 has two end faces 30 delimiting the scraper 20 along the second axis A2. A length of the scraper 20, measured along the second axis A2 between the two end faces 30, is between the internal diameter Di of the circulation duct 15 and twice the internal diameter Di.

The scraper 20 also has a lateral face 35 delimiting the scraper 20 in a plane perpendicular to the second axis A2. When the scraper 20 is substantially cylindrical, the external diameter is measured between two diametrically opposite points on the lateral face 35.

The scraper 20 comprises, for example, a shell 40 delimiting a chamber 45. In this case, the end faces 30 and the lateral face 35 are external faces of the shell 40. In particular, the shell 40 has two walls d end 46 which separate, along the second axis A2, the chamber 45 from the outside of the shell 40. In this case, the end faces 30 are faces of the end walls 46.

The end walls 46 are, for example, planar walls perpendicular to the second axis A2.

The shell 40 is, for example, made of polytetrafluoroethylene (PTFE), of Polyethylene, of a polyolefin, of polyetheretherketone (PEEK), of polyoxymethylene (POM), or also of Polyamide.

As a variant, the scraper 20 is full, that is to say that no chamber 45 is delimited by the shell 40. In this case the scraper 20 will be made of materials having good elastic properties such as an elastomer , in particular a perfluorinated elastomer, resistant to solvents.

The injector 21 is configured to inject a second fluid into the circuit 16, in particular into the circulation duct 15. For example, the injector 21 is configured to inject into the circulation duct 15 a flow of second fluid having a controllable flow rate by the injector 21.

The injector 21 is, for example, configured to inject the second fluid into the upstream end 15A of the circulation conduit 15. As a variant, the injector 21 is configured to inject the second fluid into the downstream end 15B of the circulation conduit circulation 15, or is configured to inject the second fluid either into the upstream end 15A or into the downstream end 15B.

According to the example of the figure 1 , the injector 21 is connected by a valve 47 to the circulation duct 15.

The second fluid is, for example, a fluid separate from the first fluid F to be sprayed. For example, the second fluid is a liquid, sometimes called "liquid cleaning ". The liquid is, in particular a solvent capable of dissolving or diluting the first fluid F. For example, when the first fluid F is an aqueous-based paint, the liquid is water. It should be noted that the type of solvent used is liable to vary, in particular depending on the nature of the first fluid F.

It should also be noted that liquids other than solvents may be used as the second fluid.

As a variant, the second fluid is a first fluid F intended to be sprayed after the first fluid F present in the circulation conduit 15, for example a first fluid F having a shade different from the first fluid F present in the circulation conduit 15. According to another variant, the second fluid is a gas such as compressed air.

Many types of injector 21 can be used in installation 10, depending on the second fluid to be injected. For example, the injector 21 is a gear pump, or even a compressor capable of generating a flow of gas.

It should be noted that, although the injector 21 is described above as being a device separate from the pump 12, it is conceivable that the role of the injector 21 is fulfilled by the pump 12, for example if the change changer block shades 11 comprises a reservoir of second fluid which the pump 12 is then able to inject into the conduit 15.

A first example of a method for moving the first fluid F in the installation 10 will now be described.

The method is, for example, a method for cleaning the internal surface 25 of the conduit 15. It should be noted that other applications of the method than cleaning the conduit 15 can be envisaged.

During an initial step, the first fluid F is present in the lumen of the circulation conduit 15. For example, the first fluid F partially covers the internal surface of the circulation conduit 15.

During a circulation step, the scraper 20 circulates in the circulation duct 15. For example, the scraper 20 is inserted at one end 15A, 15B of the circulation duct 15 and propelled to the other end 15A, 15B of the circulation duct 15 by a flow of second fluid.

The flow of second fluid then exerts on one of the end faces 30 a force tending to propel the scraper in the circulation duct 15 along the first axis A1.

During the circulation step 20, the first axis A1 and the second axis A2 are merged.

Under the effect of the flow of second fluid, the scraper 20 circulates in the circulation duct 15. For example, when the flow of second fluid is injected into the upstream end 15A of the duct 15, the scraper 20 circulates from upstream downstream. It should be noted that the direction of movement of the scraper 20 may vary, for example if the flow of second fluid is injected into the downstream end 15B of the conduit 15.

During its circulation, the scraper 20 pushes in front of it the first fluid F present in the circulation duct 15, thus allowing the recovery of the first fluid F. For example, a valve for recovering the first fluid F opening into the downstream end of the conduit 15 allows the outlet of the first fluid F repelled by the scraper 20. As a variant, the first fluid F exits from the circulation conduit through the valve 22 of the projection member 13.

The internal surface 25 of the circulation duct 15 is therefore cleaned, since the scraper pushes in front of it the first fluid F present on the internal surface 25 of the duct 15.

Since the difference between the first value of external diameter De1 of the scraper 20 and the internal diameter Di of the circulation duct 15 is greater than or equal to 100 μm, the friction between the scraper 20 and the internal surface 25 is limited. The wear of the scraper and of the circulation duct 15 is therefore lower than for the installations of the prior art. However, the first fluid F is effectively collected by the scraper 20.

A difference greater than or equal to 200 µm particularly reduces friction and therefore wear.

In the second, third and fourth installation examples mentioned below and their variants, the elements identical to the first example of the figure 2 and the first example of a displacement method are not described again. Only the differences are highlighted.

A second example of installation 10 is represented on the figure 3 .

The installation 10 comprises a holding system configured to prevent a relative translational movement of the scraper 10 relative to the circulation duct 15 when the scraper 20 is inserted in the circulation duct 15, and it is no longer desired that the first fluid F is displaced in the circulation duct 15 ..

The holding system is, in particular, configured to pivot the scraper 20 about a pivot axis Ap. The pivot axis Ap is perpendicular to the first axis A1.

More specifically, the holding system is configured to pivot the scraper 20 between a first position in which the first axis A1 and the second axis A2 are combined and a second position in which an angle α between the first axis A1 and the second axis A2 is strictly greater than zero.

The angle α is, for example, greater than or equal to 0.5 degrees (°).

When the scraper 20 is in the second position, as shown in the figure 3 , the scraper 20 is pressed at each of its ends against the internal surface 25 of the circulation duct 15.

Since the scraper 20 has an external diameter De1 strictly less than the internal diameter Di of the circulation duct 15, the scraper 20 is capable of moving in the circulation duct 15 without the second fluid F upstream being set in motion, for example under the influence of gravity. This happens in particular whenever the spraying is stopped.

Thanks to the holding system, the risk of an unwanted displacement of the scraper 20 is limited.

According to one embodiment, the holding system comprises a magnet 50 and a magnetic field generator 55.

The magnet 50 is integral with the scraper 20. The magnet 50 is, for example, received in the chamber 45.

The magnet 50 is, for example, a permanent magnet, such as a neodymium magnet.

However, embodiments in which the magnet 50 is an electromagnet can also be envisaged.

The magnet 50 has a north pole N and a south pole S. The north N and south S poles of the magnet 50 are aligned along a third axis A3.

The third axis A3 is not confused with the second axis A2. In particular, the third axis A3 forms an angle β with the second axis A2 of the scraper 20.

The angle β is greater than or equal to the angle α between the first axis A1 and the second axis A2. The angle β is greater than or equal to 5 °.

The magnetic field generator 55 is configured to generate, in at least a portion of the circulation duct 15, a magnetic field M tending to align the first axis A1 and the third axis A3.

The magnetic field generator 55 is, for example, placed outside the circulation duct 15. According to the example shown in the figure 3 , the magnetic field generator is in contact with the external surface 27 of the circulation duct 15.

As a variant, the magnetic field generator is included at least partially in the circulation duct 15. In particular, the field generator magnetic is at least partially between the external surface 27 and the internal surface 25 of the circulation duct 15.

The magnetic field generator 55 is, for example, an electromagnet comprising a conductive winding surrounding at least a portion of the circulation duct 15. In this case, when the electromagnet 55 is supplied by an electric current, the electromagnet 55 generates in the circulation duct 15 a magnetic field M directed parallel to the first axis A1.

According to the example of the figure 3 , the conductive winding is wound around the circulation duct 15, and is therefore in contact with the external surface 27. As a variant, the conductive winding is capable of being between the external 27 and internal 25 surfaces of the duct 15. Thus, the conductive winding is integrated in the conduit 15.

Alternatively, the magnetic field generator 55 is a permanent magnet. For example, the magnetic field generator 55 is a permanent magnet when the magnet 50 is an electromagnet.

According to a particular embodiment, the magnetic field generator 55 comprises a permanent magnet and the magnet 50 is a permanent magnet. For example, the permanent magnet of the magnetic field generator 55 is movable relative to the circulation conduit 15 between a first position in which the magnetic field generator 55 generates a negligible magnetic field in a portion of the circulation conduit 15 and a second position in which the magnetic field generator 55 generates in at least a portion of the circulation duct 15, a magnetic field M tending to align the first axis A1 and the third axis A3

According to another embodiment, the magnetic field generator 55 and the magnet 50 are both electromagnets.

The second example of a method includes a pivoting step.

The pivoting step is, for example, implemented after the circulation step. In particular, the pivoting step is implemented when the scraper 20 is received in the lumen of the circulation duct 15 but it is desired that the scraper 20 cannot move in translation along the first axis A1 relative to the circulation duct 15, for example when the circulation duct 15 must be moved or when the first axis A1 of the circulation duct 15 has a non-negligible vertical component and that the scraper 20 would be capable of sliding in the circulation duct 15 under the effect of its weight.

During the pivoting step, the scraper 20 pivots from its first position to its second position.

In particular, the electromagnet 55 generates the magnetic field M, which imposes on the scraper 20 a magnetic force tending to align the third axis A3 with the first axis A1. The scraper 20 therefore pivots about the pivot axis Ap until it reaches its second position.

The magnetic force presses the two ends of the scraper 20 against the internal surface 25 of the circulation duct 15, which prevents by friction a translational movement of the scraper along the first axis A1 relative to the circulation duct 15.

The holding system then makes it possible to hold the scraper 20 in position in a particular portion of the circulation duct 15 despite the reduction in friction between the scraper 20 and the circulation duct 15 due to the difference in internal and external diameters Di and De1. This immobilization is particularly useful in the event of interruption of the circulation stage before the entire duct 15 has been traversed by the scraper 20.

A third example of installation 10 is represented on the figure 4 .

The third example of installation 10 also includes a holding system configured to prevent a relative translational movement of the scraper 10 relative to the circulation duct 15 when the scraper 20 is inserted into the circulation duct 15.

The holding system is configured to increase the external diameter of at least a portion of the scraper 20 from the first value of diameter De1 to a second value of diameter De2.

The second value of diameter De2 is strictly greater than the first value of diameter De1.

In particular, the second value of diameter De2 is equal to the internal diameter Di.

The injector 21 is able to vary the pressure in the circulation duct 15 when the exit of the first fluid F through the downstream end of the duct 15 is prevented, for example when the valve 22 of the projection member 13 is closed.

In particular, the injector 21 is configured to vary the pressure in the circulation duct between a first pressure value and a second pressure value.

The first pressure value is a pressure value typical of the operation of the installation 10 when the scraper 20 circulates in the circulation duct 15.

The first pressure value is, for example, between 2 bar and 8 bar. Note that the first value may vary.

The second pressure value is strictly greater than the first pressure value. The second pressure value is, for example, greater than or equal to 10 bar. According to one embodiment, the second pressure value is equal to 10 bar, to within 500 millibar.

The scraper 20 is configured to be crushed along the second axis A2 when the pressure in the circulation duct 15 is greater than or equal to a predetermined pressure threshold.

In other words, the scraper 20 has an uncrushed configuration, represented on the figure 4 and an overwritten configuration shown on the figure 5 . The length L1 of the scraper 20, along the second axis A2, in the non-crushed configuration, is strictly greater than the length L2 of the scraper 20 in the crushed configuration.

The pressure threshold is strictly greater than the first pressure value and strictly less than the second pressure value.

In addition, the scraper 20 is configured so that the crushing of the scraper 20 causes an increase in the external diameter of the scraper 20 from the first value De1 to the second value De2. Thus, in the non-crushed configuration, the external diameter of the scraper 20 has the first value of diameter De1 while, in the crushed configuration, the external diameter has the second value of diameter De2.

According to one embodiment, in the crushed configuration, the external diameter has a value strictly greater than the internal diameter Di of the circulation conduit 15 when the scraper 20 is not received in the circulation conduit 15. Thus, when the scraper 20 is received in the circulation duct 15 in the crushed configuration, the external diameter of the scraper 20 has the second value of diameter De2 because the external diameter of the scraper 20 is limited by the internal diameter Di. The scraper 20 then exerts against the internal surface 25 of the circulation duct 15 a frictional force tending to keep the scraper 20 in position relative to the circulation duct 20.

For example, the shell 40 is made of a flexible polymer material and provided so that a central portion 57 of the shell 40 deforms radially outward from the shell 40 when the end walls 46 are brought together one of the other.

The flexible polymer material is, for example, chosen from a perfluorinated polymer, teflon, polyamide and a polyolefin.

According to the example of figures 1 and 5 , the scraper 20 comprises an elastic element 60.

The injector, the shell 40 and the elastic element 60 jointly form the holding system.

The elastic element 60 is received in the chamber 45 delimited by the shell 40.

The elastic element 60 exerts on the end walls 46 an elastic force tending to separate the end walls 46 from one another. In particular, the elastic element 60 is configured to exert an elastic force having a value strictly greater than a pressure force tending to bring the end walls 46 closer to one another when the pressure in the circulation duct 15 is less than or equal to the pressure threshold.

The elastic element 60 is, moreover, configured to exert an elastic force having an intensity strictly less than a pressure force tending to bring the end walls 46 closer to one another when the pressure in the circulation duct 15 is strictly greater than the pressure threshold.

In other words, the elastic element 60 is configured to maintain the scraper 20 in its non-crushed configuration when the pressure in the circulation duct 15 is less than or equal to the pressure threshold, and to allow tilting of the scraper 20 in its crushed configuration when the pressure is strictly above the pressure threshold.

The elastic element 60 is, for example, a spring such as a helical spring. It should be noted that other types of elastic elements 60 are likely to be envisaged.

The operation of the third example will now be described. In particular, a third example of a displacement method implemented by the third example of installation 10 will now be described.

During the circulation step, the pressure in the circulation duct 15 has the first pressure value. The scraper 20 is therefore in its non-crushed configuration.

The third example includes a step of increasing the pressure and a step of crushing.

During the pressure increase step, the injector increases the pressure in the circulation duct from the first value to the second value. For example, the valve 22 allowing the first fluid F to exit from the circulation conduit 15 is closed, and the injector injects second fluid into the circulation conduit 15 until the second pressure value is reached.

During the crushing step, the scraper 20 switches to its crushed configuration under the effect of the pressure force exerted on the end walls 46. The crushing causes an increase in the external diameter of the scraper 20 up to the second value of diameter De2.

When the scraper 20 is in its crushed configuration, the scraper 20 exerts a frictional force against the internal surface 25 of the circulation duct 15, since the external diameter is equal to the internal diameter Di.

The holding system then makes it possible to hold the scraper 20 in position in a particular portion of the circulation duct 15 when the scraper 20 is crushed, while allowing a reduction in friction between the scraper 20 and the circulation duct 15 due to the difference internal and external diameters Di and De1 in the non-overwritten configuration.

The holding system of the third example does not require any additional equipment except the elastic element 60, compared to the first example. In particular, no additional element external to the scraper 20 is required. The fluid spraying installation 10 is therefore very simple, and the scraper 20 can be used in already existing fluid spraying installations 10.

According to a variant of the third example, the scraper 20 does not have an elastic element 60. The shell 40 has two end portions 65 and a crushing portion 70.

The two end portions 65 define the scraper 20 along the second axis A2. In particular, each end wall 46 is a wall of an end portion 65. This end portion is delimited by the end wall 46 along the second axis 20.

Each end portion 65 is, for example, rigid. In particular, each end portion 65 is configured not to be deformed when the scraper 20 changes from the crushed configuration to the non-crushed configuration or vice versa.

The crushing portion 70 is interposed along the second axis A2 between the two end portions 65.

The crushing portion 70 is cylindrical and extends along the second axis A2. The crushing portion 70 therefore has a circular section in a plane perpendicular to the second axis A2.

The crushing portion 70 is configured to exert on the two end portions 65 a force tending to separate the two end portions 65 from one another.

In particular, the crushing portion 70 is configured to exert an elastic force having a value strictly greater than a pressure force tending to bring the two end portions 65 closer to one another when the pressure in the circulation duct 15 is less than or equal to the pressure threshold.

The crushing portion 70 is further configured to exert an elastic force having a value strictly less than a pressure force tending to bring the two end portions 65 closer to one another when the pressure in the conduit circulation 15 is strictly greater than the pressure threshold.

In other words, the crushing portion 70 is configured to maintain the scraper 20 in its non-crushed configuration when the pressure in the circulation duct 15 is less than or equal to the pressure threshold, and to allow the scraper to tilt. 20 in its crushed configuration when the pressure is strictly greater than the pressure threshold.

The crushing portion 70 is, for example, made of an elastomeric material. In this sense, the portion 70 can be qualified as an elastomeric portion.

The crushing portion 70 is configured to deform radially outward from the shell 40 when the two end portions 65 are brought closer to one another, as visible on the figure 6 .

A fourth example of installation 10 will now be described.

The scraper 20 comprises a ferromagnetic element.

Ferromagnetism designates the capacity of certain bodies to magnetize under the effect of an external magnetic field and to keep part of this magnetization.

The ferromagnetic element is, in particular, integral with the shell 40.

The ferromagnetic element is, for example, received in chamber 45.

The installation 10 includes a magnetic field generator 55.

The magnetic field generator 55 is, for example, similar to the magnetic field generators 55 used in the second example previously described.

The magnetic field generator 55 is configured to generate, in at least a portion of the circulation duct 15, a magnetic field tending to bring the ferromagnetic element closer to the magnetic field generator 55.

For example, the magnetic field generator 55 is a magnet generating a magnetic field capable of attracting the ferromagnetic element towards the magnet.

The method then comprises an attraction step replacing for example the pivoting step.

During the attraction step, the magnetic field generator 55 generates the magnetic field in the corresponding portion of the circulation duct 15. By example, when the magnetic field generator 55 is a permanent magnet, the magnetic field generator 55 is approached the portion of the circulation duct 15 in which it is desired that the scraper 20 is held.

Under the effect of the magnetic field, the ferromagnetic element is attracted towards the magnetic field generator 55. Consequently, the scraper 20 is moved in the conduit 15 until it comes into contact with the internal surface 25 of the conduit 15. In in particular, the scraper 20 is pressed against the internal surface 25.

The scraper 20 is then held in position in the portion of the duct 15 by the effect of the magnetic field which presses the scraper against the internal surface 25.

The fourth example of installation 10 is particularly simple to implement.

A method for projecting a first fluid F will now be described.

The projection method is, for example, implemented by a projection installation 10 in accordance with one of the examples of projection installation 10 described above. However, it should be noted that the spraying method is capable of being implemented by other types of fluid spraying installations, in particular fluid spraying installations in which the difference between the internal diameter Di of the duct circulation 15 and the first value De1 is strictly less than 100 micrometers, for example equal to zero.

The method includes a first projection step, a circulation step, a return step and a second projection step.

During the first projection step, a first fluid F is sprayed by the spraying installation 10. In particular, the first fluid F is injected by the pump 12 into the circulation duct 15 and transmitted by the circulation duct 15 up to 'to the projection member 13 which projects the first fluid F.

The first fluid F is, for example, projected onto an area of an object, of a structure or of an installation which it is desired to cover with first fluid F.

The first fluid F projected during the first projection step has, for example, a first shade.

The first projection step comprises determining a first volume of first fluid F. The first volume is the volume of first fluid F which has been sprayed since the start of the first projection step.

The first volume is, for example, determined by knowing the flow rate of the pump 12 and the total operating time of the pump 12 since the start of the first projection step.

The first projection step is carried out until a difference between a total volume of first fluid F to be sprayed and the first volume is equal to a second predetermined volume.

The total volume is, for example, the total volume of first fluid F to be sprayed by the installation 10 to allow the first fluid F to be covered with a predetermined object, or even a predetermined area of an object, a structure or d 'an installation.

The second volume is the volume of first fluid F that the scraper 20 is able to move during the circulation step. For example, the second volume is determined experimentally by filling the circulation conduit 15 with the first fluid F and by implementing the circulation step.

The second volume is, for example, greater than or equal to 80 percent (%) of the volume of the lumen of the circulation duct 15

The second volume is, for example, the volume of first fluid F contained in the circulation duct 15. In particular, the second volume is the volume of the lumen of the circulation duct 15.

In other words, the first projection step is carried out until the volume of first fluid F which is contained in the circulation duct 15 and which is capable of being pushed back to the projection member 13 by the scraper 20 is sufficient to cover with first fluid F the areas of the object, structure or installation which it is desired to cover with first fluid F but which have not yet been covered.

The circulation stage is implemented after the first projection stage.

During the circulation step, the scraper 20 is introduced into the circulation duct 15, for example at the upstream end 15A of the circulation duct 15, and the injector 21 injects the second fluid upstream of the scraper 20.

The second fluid used during the circulation step is, for example, a liquid, in particular a solvent capable of dissolving or diluting the first fluid F.

During the circulation step, the valve 22 is open.

The scraper 20 circulates from upstream to downstream in the circulation duct 15, under the effect of the second fluid injected into the upstream end 15A by the injector 21. For example, the scraper 20 travels a length of the duct circulation 15 greater than or equal to half a total length of the circulation duct 15, in particular greater than or equal to 90% of the total length.

The scraper 20 pushes a part of the first fluid F present in the circulation duct 15 up to the projection member 13, in particular up to the sprayer head 23.

During the circulation step, the second volume of first fluid F is pushed back by the scraper 20 to the sprayer head 23. In other words, during the circulation step, the volume of first fluid F crossing the valve 22 is equal to the second volume.

The first fluid F pushed back by the scraper 20 to the sprayer head 23 is sprayed by the sprayer head 23.

The return stage is implemented after the circulation stage.

During the return step, the injector 21 injects second fluid into the circulation duct 15 downstream of the scraper 20. The second fluid then repels the scraper 20, which moves upstream in the circulation duct.

For example, the valve 17 is open to allow the second fluid to leave the circulation duct 15 upstream of the scraper 20.

At the end of the return step, the scraper 20 is removed from the circulation duct 15.

The return stage is followed by the second projection stage.

The second projection step is identical to the first projection step except for the first fluid F projected. In particular, during the second projection step, the first fluid F injected by the pump 12 into the circulation duct 15 and projected by the projection member 13 is a first fluid F different from the first fluid F which is injected by the pump 12 during the first projection step. In particular, the first fluid F sprayed during the second spraying step has a different shade from the shade of the first fluid F sprayed during the first spraying step.

The spraying process allows the use of a large part of the first fluid F which is present in the circulation duct 15 thanks to the use of the scraper 20 to push this first fluid F to the spraying member 13. The spraying method therefore has a better yield in terms of quantity of fluid consumed than the other spraying methods, in which part of the fluid consumed remains in the circulation duct 15 at the end of the spraying, and is not effectively recovered.

When the second fluid is a liquid, the control of the second volume of projected fluid is improved, since the liquids are weakly compressible.

When this liquid is a solvent, the first fluid F remaining in the circulation conduit 15 after the passage of the scraper 20, in particular the first fluid F capable of partially covering the internal surface 25, is dissolved or diluted by the solvent and extract from line 15 with the solvent. The duct 15 is therefore partly cleaned, and the risks of contamination of the first fluid F projected during the second projection step by the first fluid F projected during the first projection step are limited.

The cleaning of the conduit 15 is further improved when the return step is implemented using this solvent used as the second fluid, since the circulation conduit 15 is then cleaned twice with the solvent, during the scraper circulations. downstream then upstream.

When the scraper 20 conforms to the scrapers 20 described in the first, second, third and fourth previous examples, that is to say when a difference between the internal diameter Di of the circulation duct 15 and the first value De1 is greater or equal to 100 micrometers (μm), the scraper 20 circulates easily even in the portions of the circulation duct 15 which are not rectilinear, in particular in the second helical portion 29. The quantity of first fluid F recovered is then increased, since it is avoided that a section of the duct 15, which cannot be traversed by the scraper 20, is still filled with first fluid F at the end of the circulation step .

The use of a second helical portion 29 makes it possible to avoid the formation, in the first fluid F contained in the second portion 29, of conductive connections under the effect of the electric fields frequently used for the projection of the first fluid F when the first fluid F contains electrically conductive particles. The scrapers 20 according to the first, second, third and fourth examples are therefore particularly advantageous for these applications.

A fifth example of installation 10 will now be described.

The elements identical to the first example of installation 10 are not described again. Only the differences are highlighted.

However, it should be noted that, in the fifth example of installation 10, the difference between the internal diameter Di of the circulation duct 15 and the first value De1 is likely to vary, in particular to be strictly less than 100 μm, by example equal to zero, or to be greater than or equal to 100 μm as is the case in the first example.

When this difference is greater than or equal to 100 μm, the fifth example of installation 10 is capable of comprising a scraper 20 and a holding system 55 conforming to the scrapers 20 and the holding systems of the second, third and fourth installation examples 10 and previously described variants of these second, third and fourth examples.

According to a variant also conceivable, the fifth example of installation 10 does not include a scraper 20.

The injector 21 is configured to inject the second fluid into at least one of the shade changer block 11, the pump 12, the circulation duct 15 and the projection member 13. According to the embodiment shown in the figure 7 , the injector 21 is connected to the shade changer unit 11 by a valve 105, to the pump 12 by a valve 110, to the circulation duct 15 by the valve 47 and to the projection member 13 by a valve 115.

The second fluid is then a liquid, for example a liquid solvent capable of dissolving or diluting the first fluid F, or else water.

The injector 21 is configured to inject a predetermined volume of second fluid into the circuit 16. The injector 21 is further configured to stop the injection when the injected volume is equal to a predetermined volume.

For example, the injector 21 is configured to estimate a value of a total volume of second fluid injected into the circuit 16 since the start of the injection, and to stop the injection when the total volume is equal to the predetermined volume.

According to one embodiment, the injector 21 comprises a control module such as a data processing unit or even a dedicated integrated circuit, suitable for estimating the total volume injected and for controlling the injection of the second fluid by the injector 21, for example suitable for controlling the opening or closing of the valves 47, 105, 110, 115. The predetermined volume is chosen as a function of the quantity of second fluid which it is desired to inject into the circuit 16. The volume predetermined is therefore likely to vary.

Examples of injectors 21 capable of being used in the fifth example are described below.

The injector 21 is further configured to inject a flow of gas into the circuit 16. In particular, the injector 21 is configured to inject the predetermined volume of second fluid into the circuit 16, and then to inject the gas into the circuit 16 to cause the displacement of the second fluid in the circuit 16.

For example, the injector 21 is connected to a source of pressurized gas.

The gas is, for example, compressed air.

The gas has a third pressure value when the gas is injected into circuit 16. The third pressure value is less than or equal to 20 bar

The fifth example of installation 10 is suitable for implementing a method comprising a step of injecting the second fluid into the circuit 16.

For example, during the injection step, the second fluid is injected into the circulation duct 15.

As a variant, the second fluid is injected into at least one of the shade changer block 11, the pump 12, the circulation duct 15, the projection member 13.

During the injection step, the injector 21 estimates the volume of second fluid injected since the start of the injection step. For example, the injector 21 periodically estimates the volume of second fluid injected since the start of the injection step. According to one embodiment, the injector 21 estimates the volume of second fluid injected with a period less than or equal to 100 milliseconds. The estimated volume is compared by the injector 21 with the predetermined volume.

If the estimated volume of second fluid is strictly less than the predetermined volume, the injector 21 continues to inject the second fluid into circuit 16.

If the estimated volume is equal to or greater than the predetermined volume, the injector 21 stops the injection. For example, the injector 21 forms the valve or valves 47, 105, 110 and 115 which connect the injector 21 to the circuit 16.

According to the example shown on the figure 7 , the injector 21 comprises a cylinder 75, a piston 80, an actuator 85 and a valve 90.

The cylinder 75 is configured to contain the second fluid. For example, the cylinder 75 delimits a cylindrical cavity suitable for accommodating the second fluid.

The cylinder 75 extends along an axis Ac specific to the cylinder 75.

It should be noted that the cylinder 75 is capable of having a circular base, but also a polygonal base, or even a base having any shape in a plane perpendicular to the axis Ac of the cylinder 75.

The cylinder 75 is, for example, made of a metallic material such as stainless steel or aluminum. The cavity delimited by the cylinder 75 has an interior volume of between 50 cubic centimeters (cc) and 1000 cc.

The piston 80 is received in the cavity delimited by the cylinder 75. The piston 80 separates the cavity delimited by the cylinder 75 into two chambers 95, 100 of variable volume.

The piston 80 is cylindrical, for example delimited by a peripheral face complementary to an internal face of the cylinder 75 and by two faces perpendicular to the axis of the cylinder 75.

The piston 80 is, for example, made of a metallic material. According to one embodiment, the face of the piston 80 which delimits the chamber 100 is made of steel stainless. As a variant, this face is made of a polymer, or else covered with a layer of polymer, or or with a layer of polytetrafluoroethylene (PTFE).

The piston 80 is movable in translation between a primary position and a secondary position relative to the cylinder 75 so as to vary the respective volumes of the chambers 95 and 100. In particular, the piston 80 is movable along the axis Ac of the cylinder 75 .

The primary position is the position in which the volume of the chamber 100 is greatest. When the piston 80 is in the primary position, the volume of the chamber 95 is, for example, equal to zero.

The secondary position is the position in which the volume of the chamber 100 is the smallest. For example, when the piston 80 is in the secondary position, the piston 80 is in abutment against an end wall of the cylinder 75, so that the volume of the chamber 100 is equal to zero.

The piston 80 is configured to prevent the passage of second fluid between the chambers 95, 100 which it delimits. For example, the piston 80 carries sealing means such as a seal surrounding the piston 80 in a plane perpendicular to the axis of the cylinder 75.

The chamber 100 is configured to be at least partially filled with the second fluid. For example, the chamber 100 is connected by the valve 90 to a source of second fluid such as a reservoir.

The chamber 100 is suitable for being connected, for example by the valve 47, to the circulation duct 15. According to the example of the figure 7 , the chamber 100 is suitable for being connected to the upstream end 15A of the circulation duct. As a variant, the chamber 100 is suitable for being connected to the downstream end 15B, or even to the two ends 15A, 15B.

The actuator 85 is configured to move the piston 80 between its primary and secondary positions. The actuator 85 comprises, for example, a motor and a rod capable of transmitting a force from the motor to the piston 80 to move the piston 80.

The actuator 85 is, in particular, configured to determine a position of the piston 80 relative to the cylinder 75, and to control or stop a movement of the piston 80 as a function of the determined position. Many types of actuators 85 allow such a determination of the position of the piston.

The motor is, for example, an electric motor such as a torque motor, or even a brushless motor.

According to one embodiment, the motor is a servomotor, that is to say a motor controlled in position. For example, the motor is controlled so as to maintain the piston 80 in a predetermined position relative to the cylinder 75, the predetermined position being liable to vary.

As a variant, the motor is replaced by a pneumatic or hydraulic member capable of moving the piston 80, for example a pump capable of injecting a liquid into the chamber 95 to move the piston.

The actuator 85 is, in particular, configured to impose on the second fluid a pressure greater than or equal to the third pressure value. For example, a pressure sensor is integrated in the chamber 100, and the control module is capable of controlling an increase in the force exerted by the actuator on the piston 80 until the pressure of the second fluid in the chamber 100 is greater than or equal to the third pressure value.

As a variant, the actuator 85 is configured to estimate the pressure of the fluid in the chamber 100 from values of an electric current supplying the electric motor of the actuator 85.

During the injection step, the chamber 100 contains second fluid and the actuator 85 moves the piston 80 in the direction of the secondary position. For example, during the injection step, the chamber 100 is filled with second fluid.

Under the effect of the displacement of the piston 80, the second fluid is injected into the circulation duct 15.

The actuator 85 periodically determines a position of the piston 80 in the cylinder 75, in particular a distance traveled by the piston 80 along the axis of the cylinder 75 from the primary position. The determination of the distance traveled is equivalent to the determination of the volume injected, since the volume injected is a bijective function of the distance traveled, i.e. a distance injected corresponds to a single volume injected.

Alternatively, the actuator 85 compares the total volume injected with the predetermined volume by determining whether or not the piston 80 has reached a predetermined position corresponding to the predetermined volume.

The predetermined position is, in particular, a position such that the displacement of the piston from the primary position to the secondary position decreases the volume of the chamber 100 by a volume value equal to the predetermined volume.

The injector 21 is, moreover, configured to stop the injection when the volume injected is equal to a predetermined volume.

For example, if the piston 80 has not reached the predetermined position, the actuator 85 continues to move the piston 80 to the secondary position.

If the piston 80 is in the predetermined position, the actuator 85 stops moving the piston 80.

Alternatively, the injector 21 is configured to close the valve 47 when the piston 80 reaches the predetermined position. It should be noted that other types of injectors 21 are likely to be used in the fifth example.

For example, the injector 21 includes a source of second fluid and a flow meter.

The source of second fluid is, for example, a reserve of second fluid at a pressure greater than or equal to the third pressure value, or else a pump capable of generating a flow of second fluid, such as a gear pump or else a peristaltic pump.

The injector 21 comprises, for example, a pressure sensor located in particular in the outlet conduit of the second fluid source, and suitable for measuring the pressure of the second fluid at the outlet of the source.

The flow meter is suitable for measuring values of the flow rate of the second fluid injected by the injector 21 into the circuit 16.

The flow is, for example, a volume flow. Alternatively, the flow is a mass flow.

The injector 21 is configured to estimate, from the measured flow values, the total volume of second fluid injected into the circuit from the start of the injection step. For example, the injector 21 estimates the total volume injected by time integration of the measured flow values.

The injector 21 interrupts the injection when the total volume is equal to the predetermined volume. For example, the injector 21 closes the valves 47, 105, 110, 15 connecting the injector 21 to the circuit 16.

The injection step is, for example implemented during a circulation step as defined above. In this case, the scraper 20 circulates from upstream to downstream in the circulation duct 15 under the effect of the second injected fluid.

As a variant or in addition, the injection step is implemented during the return step to propel the scraper 20 from downstream to upstream.

The fifth example of installation 10 is in particular suitable for implementing the projection method described above, as well as other projection methods.

For example, the fifth example of installation 10 is suitable for implementing a spraying process in which, during the circulation step, no scraper 20 is present in the duct 15. In this case, during the circulation step, the second fluid pushes the first fluid F in front of it as far as the projection member 13.

According to other possible variants, the injection step is implemented during a cleaning process of at least one of the shade changer block 11, the pump 12 and the projection member 13.

The use of an injector 21 capable of stopping the injection of second fluid when the volume of second fluid injected is equal to a predetermined volume makes it possible to precisely control the amount of second fluid used during the injection step. In particular, this volume does not depend on the viscosity of the first fluid F (or of the mixture between the first fluid F and the second fluid) present in the circuit 16, on the contrary of the methods of the state of the art in which a source of second fluid is connected to circuit 16 for a predetermined time, since the viscosity of the fluid or fluids contained in the circuit depends inter alia on the ratio between the first fluid F and the second fluid present in circuit 16.

This is particularly advantageous during a circulation step comprising the projection of the first fluid F repelled by the scraper 20 or by the second fluid, since the volume of first fluid F projected is then well controlled.

The use of a piston 80 to inject the second fluid into the circulation duct 15 makes it possible in particular to control more precisely the volume of second fluid injected, in particular when this fluid is a liquid such as a solvent, than is permitted by it the injectors 21 of the prior art. The injectors of the prior art which use pumps such as gear pumps have a flow rate which may vary depending on the average viscosity. For example, gear pumps have internal leaks which are a function of this viscosity. As a result, the volume of liquid effectively injected into the circulation duct F by the prior art injectors is not effectively controlled. On the contrary, the piston 80, by its movement, makes it possible to impose a volume of propulsion liquid actually injected, since this volume depends solely on the variation in volume of the chamber 100. The fifth example of installation 10 therefore allows better control of the amount of second fluid injected.

Estimating the volume of second fluid injected from the distance traveled by the piston 80 is a method for precisely and simply estimating the amount of volume injected into another device than the cylinder 75, the piston 80 and l actuator 85 is required.

Injectors 21 estimating the volume of second fluid actually injected from the measured flow values also allow better control of the amount of second fluid injected.

The injection of the second fluid with a pressure greater than or equal to the pressure of the gas makes it possible to use the gas to propel the second fluid, and therefore reduces the amount of second fluid required.

Estimating this pressure from the electrical current consumed eliminates the need for a sensor, and therefore simplifies the installation 10.

The invention corresponds to any technically possible combination of the embodiments described above.

Claims (10)

Method for spraying a fluid (F) by an installation (10) for spraying the fluid (F) comprising a pump (12), a sprayer (13) suitable for spraying the fluid (F) and a conduit (15) for circulation of the fluid (F) suitable for conducting the fluid (F) from the pump (12) to the sprayer (13), an upstream and a downstream being defined for the fluid circulation duct (15), the fluid (F ) flowing from upstream to downstream when the fluid (F) crosses the duct (15) from the pump (12) to the sprayer (13),
the method being characterized in that it comprises a step of circulating, in the duct (15), a scraper (20) from upstream to downstream to push the fluid (F to the sprayer (13) ) contained in the circulation duct (15), the fluid (F) repelled by the scraper (20) being sprayed by the sprayer (13). A projection method according to claim 1, in which the duct (15) has an internal diameter (Di), the scraper (20) having an external diameter, the external diameter having a first value (De1), a difference between the internal diameter (Di) of the conduit and the first value of external diameter (De1) of the scraper (20) being greater than or equal to 100 micrometers, preferably greater than or equal to 200 micrometers. A projection method according to claim 2, in which the circulation duct (15) comprises at least one helical portion (29). Spraying method according to claim 3, in which the fluid (F) is a paint comprising electrically conductive particles, in particular aluminum particles. Spraying method according to any one of claims 1 to 4, comprising a first step of spraying the fluid (F), the fluid (F) being injected into the circulation duct (15) by the pump (12) during the first projection step, the first projection step comprising determining a first volume of fluid (F) projected from the start of the first projection step, the first projection step being implemented until a difference between a total volume of the fluid (F) to be sprayed and the first volume is equal to a second volume of fluid (F) contained in the circulation duct (15), the circulation step being implemented after the first projection stage. Spraying method according to claim 5, comprising a second step of spraying a fluid (F) different from the fluid (F) sprayed during the first spraying step, the second spraying step being carried out after the spraying step circulation. Spraying method according to claim 6, in which the fluid (F) sprayed during the first spraying step has a first shade, the fluid (F) sprayed during the second spraying step having a second shade different from the first shade. Spraying method according to any one of claims 1 to 7, further comprising a return step comprising the injection of a solvent into the circulation duct (15) downstream of the scraper (20) to move the scraper (20) upstream in the circulation duct (15). Spraying method according to any one of claims 1 to 8, implemented by an installation (10) further comprising an injector (21) suitable for injecting a liquid into the circulation duct (15), in which the circulation step comprises injecting the liquid into the circulation duct (15) upstream of the scraper (20) to propel the scraper (20) downstream. A spraying method according to claim 9, in which the injector (21) comprises a cylinder (75) containing the liquid and a piston (80) received in the cylinder (75), the circulation step comprising moving the piston ( 80) in the cylinder (75) to inject the liquid contained in the cylinder (75) into the circulation duct (15).

Images