EP0561726A1 - Pump to apply a product under pressure and installation of such a pump - Google Patents

Abstract

The invention relates to a pump (8) for an installation for applying a product hot, and under pressure, which pump (8) comprises a body (9) delimiting at least one main chamber (10) in which a piston (11) moves, a means (16) for controlling the passage of the product towards the aforementioned main chamber (10) termed inlet control means, a means (17) for controlling the passage of the product towards the outlet, this pump being characterised in that it comprises: - without interference with the main circuit of the product, an auxiliary circuit (18) for a heat-exchange fluid, which auxiliary circuit includes: . a circuit (20) passing via a chamber (21) at least surrounding and as close as possible to the outlet control means (17), . a circuit (22) passing via a chamber (23) at least surrounding and as close as possible to the inlet control means (16) and, - the heat-exchange fluid which flows through at least the abovementioned inlet and outlet circuits is at a sufficiently high temperature to bring the product contained in the main temperature rapidly to a liquid state. <IMAGE>

Description

The invention relates to a pump for the application under pressure of a product which needs to be sprayed hot.

It also relates to the installation provided with said pump.

For many products used in various technical fields and in particular in the road sector, it is necessary, for its application on a support, to bring this product to a temperature higher than ambient temperature.

This is particularly the case for bitumen and so-called hot-melt paints, such as those used for road markings which must generally be previously heated to a temperature of the order of one hundred and forty degrees Celsius.

Compared to so-called traditional paints, these paints have the advantage of being more resistant over time and above all of hardening more quickly by simply lowering the temperature without requiring drying time.

To deposit these hot products, a technique known as "instant melting" is known, by which the product in the solid state, in powder or granular form, is instantly melted in a stream of hot air and conveyed in the liquid state, with the current of hot air, up to the applicator device.

• elle nécessite une quantité importante d'air pour véhiculer le produit à appliquer,
• il est difficile de doser la projection de matière solide dans le courant d'air chaud ce qui nuit à la régularité de l'épaisseur et donc à la qualité de la bande appliquée,
• pour parvenir à la fusion instantanée de la matière solide, l'air doit être chauffé à une température de l'ordre de six cents degrés Celsius ce qui implique une consommation importante d'énergie et le risque d'endommager les revêtements de chaussées servant de support au marquage,
• il est difficile de réaliser une commande séquentielle du courant d'air assurant la réalisation de traits interrompus tels des pointillés,
• une certainte quantité d'air reste emprisonnée dans le produit aprés l'application sur le sol d'où la création de bulles d'air, ce qui entraîne une mauvaise tenue du marquage dans le temps,
• en raison du mélange projeté, le durcissement est trés rapide ce qui peut nuire à la retenue des charges telles des microbilles réfléctorisantes habituellement associées au mélange et
• le mélange de l'air chaud et du produit chaud fondu donne naissance à des gaz dangereux qui n'excluent pas le risque d'explosion.

This technique has serious drawbacks, however:

• it requires a significant amount of air to convey the product to be applied,
• it is difficult to measure the projection of solid material in the current of hot air, which affects the regularity of the thickness and therefore the quality of the strip applied,
• to achieve the instantaneous melting of solid matter, the air must be heated to a temperature of the order of six hundred degrees Celsius which implies a significant consumption of energy and the risk of damaging the road surfaces used marking support,
• it is difficult to carry out a sequential control of the air flow ensuring the production of broken lines such as dotted lines,
• a certain quantity of air remains trapped in the product after application to the ground, hence the creation of air bubbles, which causes poor marking performance over time,
• due to the projected mixture, the hardening is very rapid which can adversely affect the retention of charges such as reflective microbeads usually associated with the mixture and
• the mixture of hot air and hot molten product gives rise to dangerous gases which do not exclude the risk of explosion.

• un réservoir dans lequel le produit est maintenu à une température appropriée,
• un circuit hydraulique qui relie le réservoir à un dispositif applicateur et,
• un moyen moteur pour amener le produit au dispositif applicateur.

Another type of installation is known (FR-A-2,597,521) which comprises:

• a tank in which the product is kept at an appropriate temperature,
• a hydraulic circuit which connects the reservoir to an applicator device and,
• motor means for bringing the product to the applicator device.

In this solution, the reservoir is pressurized which allows the product to be driven to the applicator device.

For safety and manufacturing cost reasons, the pressure prevailing in the tank is generally low at most of the order of six bars and therefore the product is not really sprayed but practically flows.

The quantities of product deposited per square meter are then very large and, for example, of the order of four to five kilograms and the thickness of the applied layer is at least of the order of two to three millimeters.

However, these products are very expensive and must be dosed according to real needs.

Also, it has hitherto been preferred to use traditional paints with the drawbacks that they entail.

To reduce the paint layer, there is also known a system (FR-A-1.446.291, FR-A-2.637.820) called "AIRLESS" that is to say without air in which a pump takes the product from a tank. and brings it under high pressure to the applicator means which genuinely projects the product onto the support.

The thickness of the sprayed layer is then easily controllable and can therefore be reduced to the dose just necessary if necessary.

• d'un corps délimitant au moins une chambre principale dans laquelle se déplace un piston associé à l'une des extrémités d'une tige dont l'autre extrémité est associée à un moyen de commande du déplacement de cette tige, tel un moteur hydraulique,
• d'un moyen de contrôle du passage du produit vers la chambre principale précitée dit "moyen de contrôle d'entrée",
• d'un moyen de contrôle du passage du produit vers la sortie de la chambre principale dit "moyen de contrôle de sortie".

Conventionally, the pump consists of:

• a body delimiting at least one main chamber in which a piston associated with one end of a rod moves, the other end of which is associated with a means for controlling the movement of this rod, such as a hydraulic motor,
• a means of controlling the passage of the product towards the aforementioned main chamber, known as an "inlet control means",
• a means of controlling the passage of the product towards the outlet of the main chamber called "outlet control means".

The means for controlling the passage of the product are each in particular constituted by a valve cooperating with a seat disposed at the periphery of an orifice, each of these parts being themselves said to be inlet or outlet depending on whether it belongs to the means of passage known as entry or exit.

Thus, when the piston moves in the so-called suction direction, the so-called inlet valve rises from its seat and allows the product to enter the main chamber while the so-called outlet valve is applied to its seat.

When the piston moves in the other direction, the inlet valve is applied to its seat while the outlet valve is moved away from its seat and makes it possible to evacuate the product from the main chamber, under a determined pressure, towards the applicator means.

It is understood that with such a pump when the projection of the product is stopped, for example, at the end of the day or to change the site, the product still contained in the pump will cool and solidify there.

It will thus block, if not the piston, at least one of the valves.

It will then be impossible to restart the pump except, if possible, to disassemble and clean it.

In other fields, such as that of installations intended for the compression of oxygen, in order to maintain a pump at suitable temperature, it is known to provide in the body of the pump an auxiliary circuit such as a jacket surrounding the main chamber in which circulates the piston.

In this area, the auxiliary circuit is used not for heating but for cooling the fluid present in the chamber to prevent oxygen from passing above its boiling point.

Both the field and the aim pursued are therefore foreign to the present invention.

In addition, the above provisions would not be transposable to the field of the present invention or at least, even imagining to circulate in the annex circuit a heating fluid, this would not be enough to allow the installation to operate after stop and hardening of the product in the pump.

One of the results that the invention aims to obtain is a pump which, while allowing hot spraying of a product, does not have the aforementioned drawbacks.

• sans interférence avec le circuit principal du produit, un circuit annexe 18 pour un fluide d'échange thermique avec le produit, lequel circuit annexe comprend dans le corps de la pompe une chemise 19 entourant la chambre principale et,
• outre la chemise entourant la chambre principale de la pompe sur toute sa longueur, le circuit annexe comprend :
  • . un circuit dit de sortie passant par une chambre également dite de sortie, entourant au moins et au plus prés le moyen de contrôle de sortie,
  • . un circuit dit d'entrée passant par une chambre également dite d'entrée, entourant au moins et au plus prés le moyen de contrôle d'entrée et,
• le fluide d'échange thermique qui parcourt au moins les susdits circuits d'entrée et de sortie est à une température suffisamment élevée pour amener rapidement le produit contenu dans la chambre principale dans un état liquide.

To this end, the invention relates to a pump of the aforementioned type, in particular characterized in that:

• without interference with the main circuit of the product, an annex circuit 18 for a heat exchange fluid with the product, which annex circuit comprises in the body of the pump a jacket 19 surrounding the main chamber and,
• in addition to the jacket surrounding the main chamber of the pump over its entire length, the auxiliary circuit includes:
  • . a so-called output circuit passing through a so-called output chamber, surrounding at least and most closely the output control means,
  • . a so-called input circuit passing through a so-called input chamber, surrounding at least and most closely the input control means and,
• the heat exchange fluid which flows through at least the above inlet and outlet circuits is at a temperature high enough to quickly bring the product contained in the main chamber into a liquid state.

• figure 1 : une installation de projection d'un produit,
• figure 2 : une pompe vue en coupe longitudinale.

The invention will be clearly understood with the aid of the description below given by way of nonlimiting example with regard to the attached drawing which schematically represents:

• Figure 1: a product projection installation,
• Figure 2: a pump seen in longitudinal section.

Referring to the drawing, it can be seen that the installation 1 for the application under pressure of a product 2 which, for the said application, must be brought to a temperature above ambient temperature, can, for example, be brought by a motor vehicle 3.

The application is made, for example, on a support 4 such as the ground.

The product is, for example, a hot-melt paint or bitumen etc ...

• un réservoir 5 dans lequel le produit à projeter 2 est, au moins pendant l'application, maintenu à une température appropriée,
• un dispositif applicateur 7,
• un circuit hydraulique 6 principal qui relie le réservoir 5 au dispositif applicateur 7 et,
• sur le circuit principal 6, au moins une pompe 8 pour, sous une pression élevée, amener le produit du réservoir 5 jusqu'au dispositif applicateur 7.

Conventionally, this installation includes:

• a reservoir 5 in which the product to be sprayed 2 is, at least during the application, maintained at an appropriate temperature,
• an applicator device 7,
• a main hydraulic circuit 6 which connects the reservoir 5 to the applicator device 7 and,
• on the main circuit 6, at least one pump 8 for, under high pressure, bringing the product from the reservoir 5 to the applicator device 7.

This installation 1 is of the type often called "AIRLESS", that is to say that the application of the product is done without inducing the movement of the product by a powerful flow of air, the projection being due only to the high pressure. with which the product is moved by the pump upstream of the applicator device 7.

Although this is not shown, the installation 1 includes means for adjusting, checking and regulating the aforementioned pressure.

• un corps 9 délimitant au moins une chambre principale 10 dans laquelle se déplace un piston 11 associé à l'une 12 des extrémités 12, 13 d'une tige 14 dont l'autre extrémité 13 est associée à un moyen 15 de commande du déplacement de la tige 14, tel un moteur hydraulique 15,
• un moyen 16 de contrôle du passage du produit vers la chambre principale 10 précitée dit moyen de contrôle d'entrée,
• un moyen 17 de contrôle du passage du produit vers la sortie de la chambre 10 dit moyen de contrôle de sortie.

Conventionally, the pump 8 comprises:

• a body 9 delimiting at least one main chamber 10 in which moves a piston 11 associated with one 12 of the ends 12, 13 of a rod 14 whose other end 13 is associated with a means 15 for controlling the movement of the rod 14, such as a hydraulic motor 15,
• a means 16 for controlling the passage of the product towards the aforementioned main chamber 10, said input control means,
• a means 17 for controlling the passage of the product towards the exit from the chamber 10, said exit control means.

The means 16, 17 for controlling the passage of the product are each in particular constituted by a inlet or outlet valve 16a, 17a cooperating with a seat 16b, 17b disposed at the periphery of an orifice 16c, 17c.

Each of these parts is itself said entry or exit depending on whether it belongs to the passage means said entry or exit of the product.

The control means are mounted in such a way that when one is open and lets the product through, the other is closed.

Thus, when the piston moves in the so-called suction direction, the inlet valve is moved away from its seat, allowing the product to enter the main chamber while the outlet valve is applied strongly to its seat and vice versa when the piston moves in the opposite direction.

Preferably, the means 16 for controlling the entry of the product into the main chamber is housed in the end wall 24 of the main chamber of the pump while the means for controlling the outlet of the hot-melt product is housed near otherwise the piston.

• sans interférence avec le circuit principal du produit, un circuit annexe 18 pour un fluide d'échange thermique avec le produit, lequel circuit annexe comprend dans le corps de la pompe une chemise 19 entourant la chambre principale et,
• outre la chemise 19 entourant la chambre principale 10 de la pompe sur toute sa longueur, le circuit annexe 18 comprend:
  • . un circuit 20 dit de sortie passant par une chambre 21 également dite de sortie, entourant au moins et au plus prés le moyen 17 de contrôle de sortie,
  • . un circuit 22 dit d'entrée passant par une chambre 23 également dite d'entrée, entourant au moins et au plus prés le moyen 16 de contrôle d'entrée et,
• le fluide d'échange thermique qui parcourt au moins les susdits circuits d'entrée et de sortie est à une température suffisamment élevée pour amener rapidement le produit contenu dans la chambre principale dans un état liquide.

According to the invention, the pump comprises:

• without interference with the main circuit of the product, an annex circuit 18 for a heat exchange fluid with the product, which annex circuit comprises in the body of the pump a jacket 19 surrounding the main chamber and,
• in addition to the jacket 19 surrounding the main chamber 10 of the pump over its entire length, the annex circuit 18 comprises:
  • . a circuit 20 called output passing through a chamber 21 also called output, surrounding at least and more closely the means 17 of output control,
  • . a circuit 22 known as the input circuit passing through a chamber 23 also called the input chamber, surrounding at least and most closely the means 16 for controlling the input and,
• the heat exchange fluid which flows through at least the above inlet and outlet circuits is at a temperature high enough to quickly bring the product contained in the main chamber into a liquid state.

For example, for a temperature of change of state of the product of the order of one hundred and forty degrees Celsius, the heat exchange fluid will be brought to a temperature of the order of two hundred and thirty degrees Celsius to two hundred and sixty degrees Celsius allowing the product to be heated in a reduced time, of the order of ten minutes.

According to the invention, each of the inlet and outlet chambers of the annex inlet and outlet circuits is a concentric annular chamber by means of corresponding control.

According to the invention, the so-called outlet control means 17 is housed in the piston 11 and the aforementioned outlet circuit 20 passes longitudinally through the rod 14 in order to supply the outlet chamber 21 surrounding said outlet control means 17.

According to the invention, the chamber 21 of the output circuit 20 is also concentric with the rod 14 and extends over almost its entire length.

Preferably, the distance between the chamber 21 and the external wall of the piston is as small as possible.

• contrôlé par au moins un distributeur 25a, un circuit 25 de dérivation du produit, lequel circuit de dérivation s'étend entre deux points 26a, 26b situés sur le circuit hydraulique principal, l'un 26a en amont de la pompe, l'autre 26b sur une conduite de retour du produit au réservoir et,
• un capteur 27 de l'arrêt de la projection du produit, lequel capteur, dès l'arrêt de la projection, est apte à émettre un signal de commande du distributeur 25a du circuit de dérivation 25, autorisant aussitôt la dite dérivation et donc le retour vers le réservoir 5 du produit pouvant se diriger vers la pompe 8.

According to the invention, the installation 1 further comprises:

• controlled by at least one distributor 25a, a product bypass circuit 25, which bypass circuit extends between two points 26a, 26b located on the main hydraulic circuit, one 26a upstream of the pump, the other 26b on a product return line to the tank and,
• a sensor 27 for stopping the projection of the product, which sensor, as soon as the projection is stopped, is capable of emitting a control signal from the distributor 25a of the bypass circuit 25, immediately authorizing said bypass and therefore the return towards the reservoir 5 of the product which can go towards the pump 8.

This avoids sending and then storing in the pump a fraction of product which could cool and which would then have to be removed to allow the pump to restart.

Of course, heating means are provided to bring some of the product to be applied, others the heat exchange fluid to their temperature and to control the fluctuations thereof.

Preferably, the applicator device 7 may also include a heating circuit (not shown), but this is not essential for the invention.

This applicator device consists for example of at least one spray nozzle.

In the same context, the pipes going from the reservoir to the pump and from the pump to the applicator device can also be at least insulated or even heated by a section of annex circuit parallel to said pipe or wrapped around it.

In addition to products such as hot-melt paints or bitumens, the installation can advantageously spray products which are simply more effective when hot, such as brines.

Claims (5)

Pump (8) for an installation (1) for applying pressure and hot a product (2),
which installation (1) includes: - a reservoir (5) in which the product to be sprayed (2) is, at least during the application, maintained at an appropriate temperature, - an applicator device (7), - a main hydraulic circuit (6) which connects the reservoir (5) to the applicator device (7) and, - on the main circuit (6), at least one pump (8) for, under high pressure, bringing the product from the reservoir (5) to the applicator device (7), which pump (8) comprises: - a body (9) delimiting at least one main chamber (10) in which a piston (11) moves associated with one (12) of the ends (12, 13) of a rod (14), the other of which end (13) is associated with means (15) for controlling the displacement of the rod (14), such as a hydraulic motor (15), a means (16) for controlling the passage of the product towards the aforementioned main chamber (10), said inlet control means, - A means (17) for controlling the passage of the product towards the outlet from the chamber (10), said outlet control means. this pump (8) being CHARACTERIZED in that it comprises: - without interference with the main product circuit, an annex circuit (18) for a thermal drying fluid with the product, which annex circuit includes in the pump body a jacket (19) surrounding the main chamber, - in addition to the jacket (19) surrounding the main chamber (10) of the pump over its entire length, the annex circuit (18) comprises: . an output circuit (20) passing through a chamber (21) also known as an output, surrounding at least and at most the output control means (17), . an input circuit (22) passing through a chamber (23) also called input, surrounding at least and most closely the means (16) of input control and, - The heat exchange fluid which flows through at least the above inlet and outlet circuits is at a temperature high enough to quickly bring the product contained in the main chamber into a liquid state. Pump according to claim 1 characterized in that the internal circuit (20) passes longitudinally through the rod (14) to supply the internal chamber (21). Pump according to claim 1 or 2 characterized in that the means (17) of said outlet control is housed in the piston (11) and the outlet circuit (20) passes longitudinally through the rod (14) in order to supply the chamber outlet (21) surrounding said means (17) for output control. Pump according to claim 3 characterized in that the chamber (21) of the outlet circuit (20) is also concentric with the rod (14) and extends over almost its entire length. Installation (1) provided with a pump according to any one of claims 1 to 4 which comprises: - a reservoir (5) in which the product to be sprayed (2) is, at least during the application, maintained at an appropriate temperature, - an applicator device (7), - a main hydraulic circuit (6) which connects the reservoir (5) to the applicator device (7) and, - on the main circuit (6), at least one pump (8) for, under high pressure, bringing the product from the reservoir (5) to the applicator device (7), characterized in that it comprises: - controlled by at least one distributor (25a), a circuit (25) for bypassing the product, which bypass circuit extends between two points (26a, 26b) located on the main hydraulic circuit, one (26a) in upstream of the pump, the other (26b) on a product return line to the reservoir and, a sensor (27) for stopping the projection of the product, which sensor, as soon as the projection stops, is capable of transmitting a control signal from the distributor (25a) of the bypass circuit (25), immediately authorizing the said bypass and therefore the return to the reservoir (5) of the product being able to go towards the pump (8).

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