Powdering system

A powdering system, having a working configuration and a cleaning configuration and including a powder reservoir, including a supply chamber receiving powder; a sprayer, including a powder applicator, and a cleaning inlet, fluidly connected to the supply chamber such that, in the cleaning configuration, a cleaning air supply source can be connected to the cleaning inlet so as to circulate cleaning air in the supply chamber, wherein the powder reservoir includes a discharge opening, arranged through a wall of the supply chamber and opening into the supply chamber, and a movable plug, which is movable between a closing position, in the working configuration, and an open position, in the cleaning configuration, such that the circulation of cleaning air causes residual powder to be discharged through the discharge opening.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of (i) French Patent Application No. 18 59056, filed on Oct. 1, 2018, and (ii) French Patent Application No. 18 59057, filed on Oct. 1, 2018.

FIELD OF THE INVENTION

The present invention relates to a powdering system.

The invention relates to the field of powdering, for example electrostatic powdering, which comprises applying powder on an object by spraying this powder, in order to coat this object with said powder.

BACKGROUND OF THE INVENTION

EP 2,588,244 B1 describes an electrostatic powdering system comprising a reservoir of powder and powder sprayers designed to coat an object, with powder coming from the reservoir, by spraying said powder on the object. The implemented powder is suitable for imparting a color to the coated object. Each powder sprayer comprises a respective supply line, which connects the sprayer to the reservoir, the line comprising a pump for extracting the powder from the reservoir and spraying it. In the reservoir, the powder is placed in a fluidized state owing to a fluidization plate, which is porous and located in the lower part of the reservoir. The reservoir comprises a new powder inlet for filling thereof. During the spraying of the powder, a substantial portion of the powder is not deposited on the object to be coated. This powder is recovered and reintroduced into the reservoir by a second powder inlet. The two powder inlets are located on a vertical side wall of the reservoir, near the bottom. In the same side wall, toward the top, the reservoir also comprises a fluidized air outlet.

During a powder color change, it is necessary to make sure that the reservoir is cleaned of the previous powder that may remain in the reservoir. To that end, compressed air is injected into the reservoir through the powder inlets, the powder being discharged outside the reservoir through the fluidized air outlet, while following an air roll trajectory, owing to the arrangement of the inlets and the outlet.

However, the effectiveness of the cleaning is not always optimal, residual powder being able to remain trapped in certain corners of the reservoir. The cleaning air flow is generally limited by the passage section of the fluidized air outlet, which, most often, is not provided to discharge a substantial quantity of residual powder. However, a modification to the fluidized air outlet with the aim of improving the cleaning function can prove awkward, since the fluidized air outlet must still be able to suitably provide for the discharge of the fluidized air, which is its primary function.

SUMMARY OF THE INVENTION

The invention in particular aims to resolve the aforementioned drawbacks, by proposing a new powdering system, the cleaning of which is more efficient.

To that end, the invention relates to a powdering system, having a working configuration and a cleaning configuration and comprising:a powder reservoir, comprising a supply chamber receiving powder;at least one sprayer, comprising:a powder applicator, anda supply line, connecting the powder applicator to a respective supply outlet of the supply chamber, such that, in the working configuration, the powder applicator is supplied with powder contained in the supply chamber by means of the supply line; andat least one cleaning inlet, fluidly connected to the supply chamber such that, in the cleaning configuration, a cleaning air supply source can be connected to the cleaning inlet so as to circulate cleaning air in the supply chamber;

According to the invention, the powder reservoir comprises:a discharge opening, arranged through a wall of the supply chamber and opening into the supply chamber; anda movable plug, which is movable between:a closing position of the discharge opening, adopted in the working configuration, andan open position of the discharge opening, adopted in the cleaning configuration such that the circulation of cleaning air in the supply chamber through the cleaning inlet causes a discharge of residual powder contained in the supply chamber through the discharge opening, to the outside of the supply chamber.

One idea at the base of the invention is to provide an opening dedicated to discharging residual powder, here the discharge opening. In other words, the sole function of the discharge opening is a cleaning function of the supply chamber, contrary to the prior art, where, for the cleaning, a pre-existing outlet is used, which is therefore not necessarily suitable for this second function. The invention in particular has the advantage of making it possible to provide that the discharge opening has a relatively large passage section, so as to be capable of discharging a significant quantity of residual powder and/or allowing a substantial cleaning air flow rate. It is then advantageously possible to connect a residual powder and cleaning air discharge pipe with a relatively large section. Furthermore, it is easily possible to design the cleaning opening so that it allows complementary equipment in connection with the cleaning, for example cleaning nozzles, whereas other openings having another function might not necessarily be able to receive such complementary equipment.

In the closing position, the plug makes it possible to effectively close the discharge opening so that, in the working configuration, the supply chamber is airtight and powder-tight. To enter the cleaning configuration, it is easy to move the plug to its open position. Furthermore, owing to the plug, it is easily possible to design the discharge opening such that said discharge opening defines a passage section with a large surface area, thus improving the discharge of the cleaning air and the residual powder outside the supply chamber.

Advantageous, but optional features of the invention are defined below:the discharge opening defines a cleaning air passage section.each cleaning inlet defines a cleaning air passage section.the area of the passage section of the discharge opening is greater, preferably at least two times greater, than the sum of the areas of the passage sections of the cleaning inlets.said at least one cleaning inlet comprises at least one stationary cleaning nozzle, arranged at the discharge opening while being stationary relative to the wall, said at least one stationary cleaning nozzle being designed to blow cleaning air coming from the supply source from the outside of the supply chamber, toward the inside of the supply chamber, through the discharge opening.said at least one cleaning inlet comprises at least one movable cleaning nozzle, attached to the movable plug so as to be securely movable with said movable plug, said at least one movable cleaning nozzle being designed to blow cleaning air toward the inside of the supply chamber, through the discharge opening.from the closing position to the open position, the movable plug is moved toward the inside of the supply chamber.in the closing position, the movable plug is inserted between each movable cleaning nozzle and the inside of the supply chamber.in the open position of the movable plug, each movable cleaning nozzle is at least partially positioned inside the supply chamber.the wall is a vertical wall of the powder reservoir.the powdering system further comprises a suction system to which the discharge opening is fluidly connected, to thus discharge residual powder contained in the supply chamber toward the suction system, through the discharge opening, when, in the cleaning configuration, cleaning air is circulated in the supply chamber through said at least one cleaning inlet.the powder reservoir comprises an automatic actuator, automatically positioning the movable plug in the closing position, when the powdering system is in the working configuration, and in the open position, when the powdering system is in the cleaning configuration.the powder reservoir comprises:a fluidization plate, delimiting the supply chamber, the fluidization plate emitting, in the working configuration, fluidization air of the powder contained in the supply chamber; andat least one fluidized air outlet arranged through the wall, which is configured to discharge fluidization air in the working configuration, at least one of the cleaning inlets equipping said at least one fluidized air outlet in order, in the cleaning configuration, to circulate cleaning air toward the supply chamber through said at least one fluidized air outlet.the powder reservoir comprises: an upper wall, the supply chamber being delimited by the upper wall and by the fluidization plate; and at least one side wall, connecting the upper wall to the fluidization plate and bearing the supply outlet of said at least one sprayer, the supply outlet being arranged closer to the fluidization plate than the upper wall, the outlet preferably being located at a distance smaller than 50 mm, for example smaller than 25 mm, from the fluidization plate.each supply outlet defines an outlet orifice passing through the side wall, each outlet orifice defining an orifice axis that is inclined relative to the fluidization plate, by an angle of between 30° and 60°, preferably between 45° and 55°.the powder reservoir comprises an outlet for emptying powder contained in the supply chamber, the emptying outlet passing through the fluidization plate.said at least one side wall comprises a first side wall and a second side wall opposite one another, delimiting the supply chamber between them; and a plurality of sprayers is provided, such that, for each sprayer, the supply line of the concerned sprayer connects the powder applicator of this sprayer to a respective supply outlet of the supply chamber, a first portion of the supply outlets being provided through the first side wall, a second portion of the supply outlets being provided through the second side wall.the supply chamber comprises at least one inlet for allowing powder into the supply chamber; and said at least one cleaning inlet comprises a line cleaning inlet belonging to the supply line of said at least one sprayer, the line cleaning inlet being arranged between the powder applicator and the supply outlet, such that, in the cleaning configuration, for each sprayer, the cleaning air source can be connected to the line cleaning inlet to circulate cleaning air towards the powder applicator and towards the supply chamber, via the supply line.the line cleaning inlet comprises a filter by means of which the cleaning air is injected into the supply line, the filter having a pore size smaller than the particle size of the powder, preferably a pore size smaller than 50 μm, for example a pore size smaller than 30 μm.for each sprayer, the supply line comprises a valve, arranged between the supply outlet and the line cleaning inlet, the valve moving between:an open configuration, in which the valve allows the circulation of cleaning air coming from the line cleaning inlet toward the supply chamber and toward the powder applicator, anda closed configuration, in which the valve prohibits the circulation of cleaning air coming from the line cleaning inlet toward the supply chamber, while allowing the circulation of cleaning air coming from the line cleaning inlet toward the powder applicator via the supply line.for each sprayer:the supply line comprises a pump, arranged between the powder applicator and the line cleaning inlet, andthe pump, in the working configuration of the powdering system, circulates powder contained in the supply chamber up to the powder applicator, by means of the supply line.

According to one embodiment that is independent with respect to the invention defined above, there is a powdering system, having a working configuration and a cleaning configuration and comprising:a powder reservoir, comprising a supply chamber receiving powder and comprising at least one powder intake inlet into the supply chamber; andat least one sprayer, comprising:a powder applicator; anda supply line, connecting the powder applicator to a respective supply outlet of the supply chamber, such that, in the working configuration, the powder applicator is supplied with powder contained in the supply chamber by means of the supply line.

According to this independent embodiment, the supply line of said at least one sprayer comprises a respective cleaning inlet, arranged between the powder applicator and the supply outlet, such that, in the cleaning configuration, for each sprayer, a cleaning air source can be connected to the cleaning inlet to circulate cleaning air towards the powder applicator and towards the supply chamber, via the supply line.

Owing to this independent embodiment, the powdering system comprises as many cleaning inlets as there are supply lines, which allows quick and effective cleaning, not only of the supply chamber, but also of the supply lines themselves, including the supply outlets. It is advantageously possible to provide that the cleaning air is also circulated through the powder applicator of the supply line whose cleaning inlet receives the cleaning air circulation.

The cleaning air is advantageously compressed air, or any compressed gas mixture, suitable for cleaning powder.

In the independent embodiment, the cleaning is effective, in particular inasmuch as, at the supply lines, the cleaning air follows the same path that the powder would have followed in the working configuration. Each cleaning inlet being arranged along one of the cleaning lines, first the concerned cleaning line is cleaned, the cleaning line being relatively difficult to clean in the prior art. The cleaning can be done effectively, since the circulation of cleaning air is done through each supply outlet, generally located in a lower part of the supply chamber. The cleaning air is circulated in a lower part of the supply chamber, even if the powder intake inlet is located in the upper part of the supply chamber.

Depending on the desired cleaning, using the cleaning air source, it is possible to circulate cleaning air in only one cleaning inlet at a time, in several cleaning inlets at once, or in all of the cleaning inlets at once. Preferably, the cleaning air source is connected to all of the cleaning inlets at the same time, so as to be able to circulate the cleaning air in the desired manner, by selecting one or several cleaning inlets where the cleaning air is circulated. Preferably, to switch between the working and cleaning configurations, it is not mandatory to connect and disconnect the cleaning air source with respect to the cleaning inlets, which facilitates the automation of the cleaning. Indeed, the cleaning inlets advantageously do not have a function other than the intake and/or discharge of cleaning air. It is possible to provide that the cleaning air source blows cleaning air at each cleaning inlet. It is possible to provide that the circulation is done in a pulsed or continuous manner.

Advantageous, but optional features of the independent embodiment are defined below:the cleaning inlet comprises a filter by means of which the cleaning air is injected into the supply line.the filter has a pore size smaller than the particle size of the powder, preferably a pore size smaller than 50 μm, for example a pore size smaller than 30 μm.for each sprayer, the supply line comprises a valve, arranged between the supply outlet and the cleaning inlet, the valve moving between an open configuration, in which the valve allows the circulation of cleaning air coming from the cleaning inlet toward the supply chamber and the powder applicator and a closed configuration, in which the valve prohibits the circulation of cleaning air toward the supply chamber while allowing the circulation of cleaning air toward the powder applicator via the supply line.for each sprayer:the supply line comprises a pump, arranged between the powder applicator and the cleaning inlet, andthe pump, in the working configuration of the powdering system, circulates powder contained in the supply chamber up to the powder applicator, by means of the supply line.the powder reservoir comprises:an upper wall;a fluidization plate, the supply chamber being delimited by the upper wall and by the fluidization plate, the fluidization plate emitting fluidization air of the powder contained in the supply chamber; andat least one side wall, connecting the upper wall to the fluidization plate and bearing the supply outlet of said at least one sprayer, the supply outlet being arranged closer to the fluidization plate than the upper wall, the outlet orifice preferably being located at a distance smaller than 50 mm, for example smaller than 25 mm, from the fluidization plate.each supply outlet defines an outlet orifice passing through the side wall, each outlet orifice defining an orifice axis that is inclined relative to the fluidization plate, by an angle of between 30° and 60°, preferably between 45° and 55°.the powder reservoir comprises an outlet for emptying powder contained in the supply chamber, the emptying outlet passing through the fluidization plate.the powdering system comprises the cleaning air source, fluidly connected to the supply line via the cleaning line, to circulate cleaning air to and/or from the supply chamber, by means of the supply line, when the powdering system is in the cleaning configuration.the reservoir comprises a first side wall and a second side wall that are opposite one another, delimiting the supply chamber between them.a plurality of sprayers is provided, such that, for each sprayer, the supply line of the concerned sprayer connects the powder applicator of this sprayer to a respective supply outlet of the supply chamber, a first portion of the supply outlets being provided through the first side wall, a second portion of the supply outlets being provided through the second side wall.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 4show a powdering system, including a powder reservoir1and a plurality of sprayers3. The sprayers3are partially shown inFIG. 1. Two of the sprayers3are schematically shown in each ofFIGS. 3 and 4.

Here, twenty-four sprayers3are provided for the reservoir1. In a variant, a number of sprayers3different from twenty-four is provided, at minimum a single sprayer3.

The powdering system changes between a working configuration and cleaning configuration. The cleaning configuration is in particular implemented before the introduction, into the reservoir1, of a new powder whereof the characteristics, for example a color, are different from those of a residual powder previously contained in the reservoir.

In the working configuration, the powdering system is designed to perform a powdering, preferably an electrostatic powdering, by means of sprayers3, in order to coat one or several objects, not illustrated, with the powder contained in the reservoir1. The powder can in particular be used to paint the object in question.

The powder in question is for example a thermosetting resin powder.

The reservoir1is advantageously generally parallelepiped. In this case, the reservoir1comprises four side walls7,9,11and13, which are advantageously vertical during the use of the reservoir1. These side walls in particular comprise a front side wall7and a rear side wall9, which are opposite and parallel, as well as a left side wall11and a right side wall13, which are opposite and parallel, the side walls11and13each connecting the walls7and9to one another. The reservoir1also comprises an upper wall15and a bottom wall17, which are opposite and advantageously parallel to one another. At their respective perimeter, the walls15and17close the side walls7,9,11and13, respectively by the top and the bottom.

The reservoir1advantageously comprises a plate19, arranged inside the reservoir1, as a partition, between the upper wall15and the bottom wall17. The plate19is advantageously parallel to the bottom wall17. At its perimeter, the plate19connects the walls7,9,11and13. Thus, each side wall7,9,11and13connects the plate19to the upper wall15and to the bottom wall17.

The reservoir1comprises a supply chamber5, visible inFIGS. 2-4, above the plate19. In the example of the figures, the chamber5is delimited by the walls7,9,11,13and15and by the plate19, so as preferably to define a generally parallelepiped volume. The chamber5is therefore arranged between the opposite side walls11and13, and between the opposite side walls7and9, which delimit the chamber5between them. The chamber5advantageously constitutes a rigid volume, due to the rigidity of the walls7,9,11,13and15of the plate19. The chamber5for example defines a volume of between 1 liter and 30 liters, and can have a maximum content of between 1 and 15 kilograms of powder.

The reservoir1, and in particular the walls7-17, constitute an airtight and powder-tight closed enclosure, aside from the various inlets and outlets of the reservoir1described below. Within the meaning of the invention, each “inlet” and “outlet” for example comprises an orifice or an opening by which a fluid, such as air or powder suspended in the air, can respectively enter or leave an adjacent space.

Preferably, the upper wall15is passed through by an access opening, for access to the chamber5by a person for maintenance purposes, placing the chamber5in communication with the outside of the reservoir1. The access opening can be closed by a removable cover27of the reservoir1. In the working configuration and the cleaning configuration, this access opening is closed in an airtight manner by the removable cover27.

In the working configuration, the chamber5receives powder to supply sprayers3in order to coat the object to be coated. To that end, the reservoir1comprises one or several powder inlets29, which are carried for example by the upper wall15. Each inlet29is connected to a powder supply source of the reservoir1, which is preferably automatic. Here, two inlets29are provided, one being used to admit new powder into the chamber5, the other being used to admit recycled powder into the chamber5. “Recycled powder” refers to powder recovered, and optionally treated, after a previous spraying operation on an object. In the working configuration, the powder contained in the chamber5is placed in a fluidized state, i.e., placed in suspension, so as to be distributed and set in motion in the volume of the chamber5. To that end, the plate19is a porous fluidization plate. As shown inFIG. 3, from the plate19, fluidization air F19is emitted and injected into the chamber5, so as to be distributed over all or most of the surface of the plate19.

Preferably, the reservoir1delimits a fluidization air chamber21, delimited by the plate19and the walls7,9,11,13and17, below the plate19, within which compressed air is introduced under pressure, so as to pass through the plate19to be introduced into the chamber5and thus fluidize the powder contained in the chamber5. The fluidization air is advantageously introduced into the chamber21by a compressed air source23, by means of a fluidization air inlet25, emerging in the chamber21, and being arranged through one of the walls of the reservoir1. The plate19is porous to be passed through by the fluidization air F19and allow its passage from the chamber21into the chamber5. However, the plate19is impermeable to the powder contained in the chamber5, in order to prevent this powder from entering the chamber21. To that end, the porosity of the plate19is smaller than the particle size of the powder.

Due to the fluidization, the chamber5and the chamber21are under pressure in the working configuration.

As shown schematically inFIG. 1, advantageously, at least one fluidization air outlet80is provided through the wall7. Preferably, two outlets80are provided. Each outlet80is different from the other inlets and outlets described in this document. Each fluidization air outlet80is advantageously connected to a suction system79illustrated schematically inFIGS. 1 and 2, by means of a respective valve81. The valve81is preferably a sleeve valve, actuated by a compressed air source.

Preferably, each outlet80is connected to the suction system79, in the working configuration and in the cleaning configuration, which makes the automation easier by avoiding having to connect and disconnect the suction system79. In the working configuration, each outlet80makes it possible to discharge fluidized air introduced into the supply chamber5to the system79. To that end, the sleeve valve81is then open. The suction system79is designed to discharge, recycle and/or treat the residual powder coming from the chamber5.

Preferably, a respective cleaning air inlet82is also provided, equipping each of these fluidization air outlets80, outside the reservoir1. The air inlet82makes it possible to introduce cleaning air into the chamber5, via the orifice formed by the outlet80. To that end, a cleaning air source55is fluidly connected to the air inlet82. The cleaning inlet82for example comprises a fluid coupling, in order to connect a cleaning air pipe supplied by the source55. The source55is advantageously a compressed air source, the compressed air serving as cleaning air.

The air inlet82is used in the cleaning configuration and is advantageously not used in the working configuration. If such an inlet82is provided, the cleaning inlet82is preferably inserted between the sleeve valve81and the fluidization air outlet80. In the cleaning configuration, the cleaning of the chamber5can thus be done from each outlet80, cleaning air being introduced from each inlet82into the chamber5, via each concerned respective outlet80.

In the cleaning configuration, the respective valve81of each outlet80is advantageously kept closed, such that cleaning air can be injected toward the chamber5through the inlet82, via the outlet80.

The cleaning inlet82advantageously comprises a gate, closing off the circulation of powder through the cleaning inlet82while authorizing the circulation of air. Thus, the gate substantially prevents any rising of powder toward the source55.

In the cleaning configuration, when one wishes for cleaning air to be introduced only through cleaning inlets other than those described below, the valve81can either be closed or open.

The reservoir1preferably comprises an outlet31for emptying powder contained in the supply chamber5. The outlet31is provided through the plate19and is able to conduct the powder from the inside of the chamber5to the outside of the reservoir1. More specifically, the outlet31comprises a pipe, passing through the wall17, the chamber21and the plate19, and opening at one end into the chamber5, and at the other end outside the reservoir1. The outlet31bears, outside the reservoir1, a valve32in order to be able to be open or closed. In the working configuration and in the cleaning configuration, the outlet31is closed. Preferably, the valve32is a sleeve valve, actuated by a compressed air source.

The reservoir1preferably comprises a vibrator34, carried by the front wall7, outside and at the height of the chamber5.

The reservoir preferably comprises one or several sensors36, carried by the rear wall9, in order to determine the powder level in the chamber5.

The reservoir1comprises a discharge opening60, arranged through the front wall7and opening into the supply chamber5. It will be noted that the opening60is different from the other inlets and outlets mentioned in the present document.

The reservoir1advantageously comprises a connection coupling65, here comprising an annular collar66and a tubular pipe67. The tubular pipe67is attached to the wall7by a first end, so as to surround the opening60. At its other free end, the tubular pipe67bears the collar66. The collar66is provided with orifices for receiving screws or the like, in order to fluidly connect the opening60to the suction system79, as shown schematically inFIGS. 1 and 2. For example, the collar66is connected to the suction system79via a suction pipe of the suction system79. Preferably, the opening60is connected to the suction system79, in the working configuration and in the cleaning configuration, which makes it possible to avoid having to connect and disconnect this suction pipe so as to make the automation easier.

As is better visible inFIG. 2, the reservoir1comprises a movable plug61, which goes between a position closing the opening60, adopted in the working configuration, and an open position of the opening60, adopted in the cleaning configuration. The plug61constitutes a removable stopper. To go between its closed and open positions, the plug61advantageously moves in translation along an axis X61orthogonal to the wall7. The pipe67, if it is provided, is advantageously coaxial with the axis X61.

Preferably, the plug61assumes a discoid shape, an edge63delimiting the opening60in turn having a corresponding circular shape, so as to surround and marry the contour of the plug61, when the plug is in the closing position.

FIG. 2shows the plug61in the closing position. In the open position, the plug is moved along the axis X61toward the inside of the chamber5, i.e., inFIG. 2, to the right. Once the open position is reached, the plug61is preferably completely inside the chamber5, whereas in the closed position, the plug61is preferably positioned in the plane of the wall7. Owing to these arrangements, the pressure of the air inside the chamber5tends to press the plug61toward its closed configuration, which guarantees the tightness of the closure against air and powder.

Preferably, when the plug61is moved toward the open position, the plug61opens an annular passage delimited between the circumference of the plug61, with the circular contour, and the circumference of the opening60, also with the circular contour. In the closing configuration, the plug61bears in an airtight and powder-tight manner against the edge63, constituting a sealing seat, for example a conical bearing centered on the axis X61. In order to obtain a conical bearing, as shown in the figure, it is provided that the contour of the plug is conical, like the contour of the opening60, which has a complementary conical shape.

In a variant, other complementary shapes can be provided for the plug61and the opening60.

In order to actuate the movement of the plug61automatically between its two aforementioned positions, the reservoir1advantageously comprises an automatic actuator69, for example an axial pneumatic jack, which is parallel or coaxial to the axis X61. The position of the plug61is therefore modified automatically by the actuator69, depending on whether the powdering system is in the working configuration or the cleaning configuration. The actuator69is advantageously located outside the chamber5, the plug61then being inserted between the actuator69and the chamber5to protect the actuator69, in particular in the closing position. The plug61is advantageously carried by the actuator69, by means of a rod coaxial with the axis X61, connecting the actuator69to the plug61.

As shown inFIG. 2, the reservoir1preferably comprises one or several cleaning inlets at the opening60, which assume the form of cleaning nozzles70. Each nozzle70is supplied by a cleaning air source. Preferably, the same cleaning air source55as that mentioned above supplies the nozzles70with cleaning air.

Each nozzle70is arranged by being oriented toward the opening60, more specifically toward the annular gap formed between the contour of the plug61and the seat63when the plug61is in the open position. Here, the nozzles70are arranged between the actuator69and the plug61, along the axis X61. When several nozzles70are provided, they are preferably regularly distributed around the axis X61, as shown inFIG. 2. Each nozzle70is preferably inclined relative to the axis X61, so as to spray an oblique flow of air, which is therefore both oriented in a centrifugal direction relative to the axis X61and oriented toward the inside of the chamber5.

In the present example, the nozzles70are movable nozzles. Indeed, the nozzles70are fastened to the plug61and therefore move jointly with said plug61, when the plug61is movable between the open and closing positions. In the closing position of the plug61, the nozzles70are withdrawn relative to the seat63, toward the outside of the reservoir1, along the axis X1, as shown inFIG. 2. In the closing position, the movable plug61is inserted between each movable cleaning nozzle70and the inside of the supply chamber5. Thus, in the working configuration where powder in the fluidized state is present in the chamber5, the movable nozzles70are protected from said powder.

When the plug61enters the open position, the nozzles70are brought to the height of the seat63, or past the seat63, along the axis X1, so as to be at least partially positioned inside the chamber5, when the open position is reached. It is possible to provide that, in the open position, the plug61is further forward toward the inside of the chamber5, such that the nozzles70are completely positioned inside the chamber5. Whatever the selected solution, the movement of the nozzles70under the action of the plug61makes it possible both, in the cleaning configuration, to extend the blowing zone, and in the working configuration, to protect the nozzles70.

In the open position, each nozzle70can blow cleaning air toward the inside of the supply chamber5, through the discharge opening60. Preferably, the blowing of the nozzles70is activated automatically when the plug61is in the open position, i.e., when the reservoir is in the cleaning configuration.

As is better visible inFIGS. 3 and 4, each sprayer3comprises a powder applicator41. The applicator41is arranged outside, and preferably at a distance from, the reservoir1. For example, the applicator41assumes the form of a sprayer or a powder gun, able to be manipulated by hand or by a robot, or which is stationary. In the working configuration, each applicator41is able to spray powder toward an object to be coated, in order to coat it with the powder thus sprayed.

For the preferred case of an electrostatic powdering, the powdering system comprises means for applying an electric charge to the powder, these means for example belonging to the applicator41. The object to be coated is in turn advantageously grounded, or bears a negative electric charge, such that the powder, sprayed by the applicator41against the object, is attracted by Coulomb force and adheres to this object. Preferably, the object thus coated with powder is next passed through a furnace, in particular to cause a permanent adhesion of the powder to the object by polymerization.

Preferably, the portion of the powder that has not coated the object is recovered in order to be reintroduced into the reservoir1as recycled powder, after possible treatments such as filtering, via one of the inlets29.

Each sprayer3comprises a supply line43, connecting the applicator41to a respective supply outlet45of the supply chamber5. It will thus be understood that the sprayers3are connected to the chamber5by individual outlets45. If a single sprayer3is provided, a single outlet45is provided. It will be noted that the outlets45are separate from the outlet31. More specifically, as shown inFIGS. 2-4, each outlet45defines an outlet orifice that passes through one of the two side walls11or13. Each outlet orifice is generally cylindrical, coaxial with an orifice axis X45. Each orifice axis X45is inclined relative to the fluidization plate19, by an angle a45of between 30° and 60°, ideally between 45° and 55°. InFIGS. 2-4, the angle is 50°.

In the event there are multiple sprayers3, like in the figures, each outlet45is advantageously provided through one of the side walls11and13. Each wall11and13advantageously includes several outlets45, and thus supplies several sprayers3. Preferably, an equal number of sprayers3is connected to the chamber5via the wall11and via the wall13, each wall11and13bearing an equal number of outlets45. In other words, a first portion of the outlets45is provided through the side wall11and a second portion of the outlets45is provided through the side wall13.

Each outlet45is arranged closer to the fluidization plate19than the upper wall15. In practice, the outlets45are placed as close as possible to the plate19. Preferably, each outlet orifice45is located at a distance smaller than 50 mm, for example smaller than 25 mm, from the fluidization plate. On each wall11and13, the outlets45are distributed from the wall7to the wall9, preferably regularly. As better shown inFIG. 2, here, each wall11and13receives a plurality of outlets45arranged in a row parallel to the plate19. This arrangement makes it possible for the entire area of the chamber5containing powder to be able to supply the sprayers3, with no area of the chamber5where powder could not be recovered by the sprayers3.

In the working configuration, each applicator41is supplied with powder contained in the supply chamber5means of the outlet45by means of its respective supply line43, by to which the line43is connected.

Each line43advantageously comprises a valve47, which is preferably directly connected to the outlet45of this line43by a pipe44, without bypass, belonging to the line43. The valve47makes it possible to open and close the line43. In other words, the valve47moves between an open configuration, in which the valve47allows the supply of the applicator41with powder contained in the chamber5, by means of the supply line43, and a closed configuration, in which the valve47prohibits the supply of the applicator41with powder contained in the chamber5, by means of the supply line43. In the working configuration, each valve47makes it possible to choose whether the applicator41that is connected thereto can or cannot be supplied with the powder coming from the chamber5, the valve47closing or opening the line43. Preferably, each valve47is a sleeve valve, actuated by a compressed air source.

Each line43preferably comprises a cleaning inlet49, which is advantageously directly connected to the valve47by a pipe48, without bypass, belonging to the line43, such that the valve47is fluidly inserted between the inlet49and the outlet45. The cleaning inlet49is used in the cleaning configuration, but preferably is not used in the working configuration. The cleaning air source55is fluidly connected to the supply line43via the cleaning inlet49. It may involve the same cleaning air source as for the inlets70and/or82, or a second, separate cleaning air source. The cleaning inlet49for example comprises a fluid coupling, in order to connect a cleaning air pipe supplied by the source55.

The cleaning inlet49can be described as “line cleaning inlet” even if its cleaning action is not necessarily limited to the line43to which the inlet49belongs.

The cleaning inlet49advantageously comprises a porous filter, closing off the circulation of powder through the cleaning inlet49while authorizing the circulation of air. Thus, the porous filter substantially prevents any rising of powder toward the source55. Preferably, the porous filter is made from a porous material, and for example assumes the form of a tube made from a porous material. The porous filter, in particular its porous material, has a porosity smaller than the particle size of the powder, preferably smaller than 50 μm (micrometers), for example smaller than 30 μm.

As illustrated inFIG. 4by the arrows F55, in the cleaning configuration, the source55circulates cleaning air, preferably under pressure, from certain inlets49, into the chamber5. To reach the chamber5from one of the inlets49, the cleaning air circulates via the pipe48, via the valve47, if such a valve47is provided inserted between the inlet49and the outlet45, via the pipe44and via the outlet45. Cleaning air reaches the chamber5only if the valve47is in the open configuration.

FIG. 4shows a case where cleaning air is injected only through the inlets49located on the right inFIG. 4, i.e., from lines43attached to the wall11. In this situation, the air circulates in the chamber5along a spiral trajectory, so as in particular to sweep over the plate19and the side wall13opposite said wall11. The circulation of cleaning air in the chamber5is very turbulent, such that the cleaning is particularly effective. The residual powder is necessarily dislodged from the outlets45and valves47, which are directly on the path of the cleaning air circulating in the line43. The outlets45advantageously being oriented on an incline toward the plate19, the cleaning air strikes the plate19with force, near each outlet45supplied by cleaning air.

The cleaning air thus circulated loosens, and carries with it, residual powder contained in the various elements of the powdering system that the air, thus circulated, passes through. In particular, the chamber5is cleaned, as well as the outlets45and the valves47.

Each line43advantageously comprises a pump51, which is advantageously directly connected to the cleaning inlet49by a pipe50, without bypass, belonging to the line43. Another pipe52, without bypass, belonging to the line43, connects the pump51to the applicator41. Thus, the pump51is fluidly inserted between the inlet49and the applicator41. In the working configuration, upon command by a user or a logic controller, as shown inFIG. 3, the pump51suctions the powder contained in the chamber5via the outlet45and sends it toward the applicator41via the pipe52. InFIG. 3, the path of the powder thus circulated by the pump51is shown by the arrows F51.

For each line43, the circulation of the powder is possible when the valve47is in the open configuration. In other words, the pump51, in the working configuration of the powdering system, circulates powder contained in the chamber5up to the applicator41, by means of the supply line43of this pump51. The pump51provides enough kinetic energy to the powder to obtain the spraying thereof outside the applicator41. The pump51is advantageously a Venturi effect pump, comprising at least one compressed air supply inlet53, for its operation.

In the cleaning configuration, when the source55injects cleaning air through the inlet49, it is possible to provide that the valve47is in the closed configuration, such that the cleaning air is circulated into the applicator41, via the pipe50, the pump51and the pipe52, as shown by the arrow in dotted lines inFIG. 4. The cleaning of the portion of the projector3extending into the applicator41is then particularly effective.

In the cleaning configuration, it is also possible to provide that the valve47is in the open configuration, such that the cleaning air is circulated not only into the applicator41, by means of the pipe50, the pump51and the pipe52, but also into the chamber5, by means of the pipe48, the valve47, the pipe44and the outlet45. A complete cleaning of the line43is then done, advantageously with a greater effectiveness on the chamber5side than on the applicator41side.

More generally, the valve47, the cleaning inlet49, the pump51are each fluidly inserted, along the line43, between the applicator41and the outlet45. The valve47, the cleaning inlet49, the pump51and the applicator41are connected in series, successively one after the other, along the line43.

When, in the cleaning configuration, cleaning air is circulated toward the supply chamber5from one or several of the inlets49,70and/or82, the residual powder is transported by the cleaning air outside the reservoir1, in particular outside the chamber5, via the opening60, the plug61of which is then in the open position. It is then advantageous to provide that the suction system79is connected to the outlet60. Inasmuch as, in the cleaning configuration, a significant quantity of cleaning air is circulated through the chamber5, it is preferable to provide that the opening60is large. As shown by crosshatching inFIG. 4, in the open configuration of the plug61, the discharge opening60defines a cleaning air passage section S60, preferably delimited by the contour of the opening60and in a plane orthogonal to the axis X61. Likewise, as shown inFIG. 2, each cleaning inlet49,70and82defines a cleaning air passage section. Each of these passage sections is delimited by the contour of the opening of the cleaning inlet in question. The area of the section S60is advantageously greater than the sum of the areas of the sections of all of the cleaning inlets49,70and82. Preferably, the area of the section S60is more than two times greater than the sum of the areas of the sections of all of the cleaning inlets49,70and82. The section S60being large, the expulsion of the residual powder outside the chamber5is made easier, since the chamber5can be subjected to a very significant cleaning air flow rate.

In the cleaning configuration, the cleaning air can be injected through all of the inlets49,70and82at the same time, or through only some of the inlets49,70and82, or sequentially, i.e., by modifying the set of inlets49,70and82supplied with cleaning air over time. For example, when cleaning air is introduced through the nozzles70after a phase for injecting cleaning air through the inlets49, the cleaning air creates a new turbulent flow of air to complete the cleaning of the supply chamber5. Whatever the case may be, this cleaning air is suctioned by the suction system79via the opening60.

Preferably, a single compressed air source, grouping together the sources23and55, supplies air in different parts of the powdering system selectively and automatically. This single compressed air source for example supplies all or some of the following elements: the valve32, the valves47, the cleaning inlets49,70and82, the pumps51, the chamber21and the actuator69. For example, this single compressed air source comprises a compressed air generator and a network of compressed air pipes connected to the generator and to the different parts of the powdering system, in order to selectively supply these parts of the powdering system with the compressed air thus generated. To select the parts of the powdering system to be supplied, the network of pipes comprises a set of air distributors and pumps, as well as a logic controller controlling the set of distributors and pumps.

In a variant, it has been seen that separate compressed air sources can supply the different parts of the powdering system. In this case, each air source can for example supply a group of parts of the powdering system, for example a group made up of all of the inlets49, or group made up of all of the inlets49,70and82. In particular, if the cleaning air must have a composition different from that of the compressed air supplying the other parts, in particular for the fluidization of the powder or the supply of the pumps51, it is for example possible to distinguish a cleaning air source and one or several sources of air intended for the other functions of the powdering system. In this variant, each compressed air source comprises, for example, an air generator for cleaning and a network of compressed air pipes connected to the generator and to the various affected air inlets of the powdering system, via their respective connector. To select the air inlet(s) to be supplied, the network of pipes comprises a set of air distributors and pumps, as well as a logic controller controlling the set of distributors and pumps.

The aforementioned powdering system is configured to implement a cleaning method, when the cleaning system is in the cleaning configuration. In this cleaning method, the cleaning is done according to an automatic program, where the inlets49,70and/or82are supplied in a predetermined manner, and optionally variable over time. For example, it is possible to provide for supplying, in turn, the inlets49of the sprayers3connected to the wall11, then the inlets49of the sprayers3connected to the wall13, and vice versa. For example, it is possible to provide for supplying, in turn, each inlet49, or groups of inlets49, sequentially, according to a predetermined order. Thus, the cleaning air flows generated in the chamber5can be modulated and modified throughout the cleaning, or can be made more turbulent by quickly changing the set of inlets49,70and/or82admitting cleaning air. The cleaning is therefore improved.

In a variant that is not illustrated, all or some of the cleaning nozzles70are stationary relative to the wall7. To that end, these stationary nozzles are attached to a stationary part of the reservoir1, at the opening60, i.e., near or through this opening. For example, each stationary nozzle is attached to the pipe67, the wall7or the edge of the opening60. Preferably, the stationary nozzles are placed outside the chamber5, so as to blow cleaning air from the outside of the chamber5toward the inside of the chamber5, when the plug61is in the open position. Also in this case, when the plug61is in the closed position, the plug61is advantageously inserted between the stationary nozzles and inside the chamber5.

Any feature of an embodiment or a variant defined hereinabove can be implemented for the other embodiments and variants defined hereinabove.