EP2755800B1 - Device for spraying dry ice, particularly frozen carbon dioxide - Google Patents

Description

The present invention relates to a device for blasting dry ice, in particular dry ice.

It will find its applications, in particular, in the field of cleaning surfaces, especially large surfaces such as vehicle body parts. This example is not, however, limiting and the invention will also find its applications, in particular, for cleaning parts of smaller sizes.

Dry ice blasting is effective in the combination of different effects, a mechanical effect due to the kinetic energy of the ice particles, a thermal effect due to the temperature of the particles and a blast effect due to the sublimation of the ice in contact with the surface to be cleaned. It also has the advantage of not leaving residues. Indeed, after sublimation, the dry ice, transformed into gas, evacuates itself.

Various methods of dry ice blasting have already been proposed. It is thus known to project previously formed particles or pellets of ice using a firing machine. However, this process can be too violent for fragile surfaces.

It is also known to form ice particles from carbon dioxide in the liquid state in contact with a driving fluid which entrains the particles as they are created and also serves to project them onto the surface to be formed. clean.

To implement the latter method, there are known devices comprising a supply of motor fluid, a supply of liquid carbon dioxide, a chamber for forming dry ice particles and a nozzle projecting, under the action of the driving fluid, the particles formed in the chamber. Such a device is described in the document EP-1765551 .

The document DE 102005021999 also illustrates this state of the art of such projection devices and serves as a basis for the preamble of claim 1.

Such devices are particularly suitable for projecting the flow of ice particles in a direction orthogonal to the surface to be cleaned. Difficulties arise when it is desired to project the fluid in an inclined direction, particularly in the case of surface to be cleaned having a complex profile.

A first solution to solve this problem would be to tilt the device in the desired direction but, given their size, it would cause problems overhang.

Another solution would be to direct the flow out of the nozzle but it would create losses that would greatly degrade the cleaning performance. Indeed, the flow of ice particles, greatly accelerated after passage through the nozzle, is particularly sensitive to any disturbances.

The invention, defined in claim 1, is intended to improve the situation and proposes for this purpose a dry ice particle projection device, in particular for cleaning surfaces, comprising a gun, for orienting a driving fluid driving said particles in a first direction, and a projection nozzle, allowing the passage of said driving fluid, charged with said particles, said nozzle comprising a neck.

According to the invention, said device is configured to orient the fluid, charged with said particles, in at least one other direction upstream of the neck, according to the direction of flow of the driving fluid. There is thus a solution for orienting the flow of particles in the desired direction while limiting the losses of charges.

For the avoidance of doubt, the term "section" is used in the following to mean the section of the nozzle in a plane orthogonal to the main direction in which the nozzle conducts the fluid passing through it.

• la buse est configurée pour dévier le fluide moteur, chargé desdites particules, dans la ou les autres directions,
• la buse comprend une portion de déviation, apte à modifier la trajectoire dudit fluide moteur, chargé desdites particules, de ladite première direction dans la ou lesdites autres directions, ladite portion de déviation étant située en amont du col,
• la buse comprend un convergent et ladite portion de déviation est située au moins en partie au niveau dudit convergent,
• la buse comprend une portion de section constante, destinée à être situé en amont du convergent dans le sens d'écoulement du fluide moteur, ladite portion de section constante étant apte guider le fluide moteur, chargés desdites particules, selon ladite première direction.

According to different embodiments of the invention that can be taken together or separately:

• the nozzle is configured to deflect the driving fluid, charged with said particles, in the other direction or directions,
• the nozzle comprises a deflection portion, adapted to modify the path of said driving fluid, charged with said particles, of said first direction in said other direction or directions, said deflection portion being located upstream of the neck,
• the nozzle comprises a convergent and said deflection portion is located at least partly at the level of said convergent,
• the nozzle comprises a portion of constant section, intended to be located upstream of the convergent in the direction of flow of the driving fluid, said portion of constant section being adapted to guide the driving fluid, charged with said particles, in said first direction.

According to one aspect of the invention, said nozzle comprises a divergent allowing acceleration of said driving fluid according to said one or more other directions.

Said divergent extends between the neck and an outlet orifice of the nozzle, the ratio between the surface of the neck and the surface of said outlet orifice of the nozzle being, for example, greater than 0.2, especially greater than 0.5. , in particular greater than 0.73. Said ratio will, for example, be less than 0.9.

The applicant has indeed found, following numerous tests, that such a divergent allowed to limit the consumption of carrier fluid while obtaining very good cleaning results, especially in terms of eliminating greasiness present on objects to clean. The invention will more generally find its applications for the cleaning of fine pollution, thickness less than 3 mm, among others. It also allows the use of nozzles of limited size, including the nozzles having divergents whose length between the neck and the outlet orifice of the nozzle is less than 50 mm.

According to a first embodiment, said divergent portion has a rectangular section.

• la longueur l de ladite section croit de façon linéaire en allant du col vers l'orifice de sortie de la buse,
• ladite section présente une largeur ou hauteur sensiblement constante, en allant du col vers l'orifice de sortie de la buse,
• l'orifice de sortie de la buse se présente sous la forme d'une fente présentant une largeur ou hauteur inférieure à 1,5 mm et/ou une longueur comprise entre 20 et 50 mm,
• le col présente une section rectangulaire.

According to different aspects of this first embodiment, which can be taken together or separately:

• the length l of said section increases linearly from the neck to the outlet orifice of the nozzle,
• said section has a substantially constant width or height, from the neck to the outlet orifice of the nozzle,
• the outlet orifice of the nozzle is in the form of a slot having a width or height less than 1.5 mm and / or a length of between 20 and 50 mm,
• the neck has a rectangular section.

According to another embodiment of the invention, said divergent has a circular section. The neck may then have a circular section.

For the avoidance of doubt, the term "angle of divergence" will have the following meaning in the following. For the nozzles whose divergent has a rectangular section in which the length l linearly increases, it is the angle corresponding to the slope of increase of said length l of the divergent. For the nozzles whose divergent has a round section, it is the angle at the top of the cone bearing the truncated cone forming the divergent.

According to a first variant, the divergent device according to the invention has a divergence angle α of the order of 6 °. This gives a high cleaning efficiency.

According to a second variant, said divergent has a divergence angle α greater than 7 °, in particular greater than 15 °. A flared jet is then obtained with an enlarged impact surface.

In these different variants, the length L of the divergent measured between the neck and the outlet orifice of the nozzle, the length _S of the section of the divergent at said nozzle outlet and the divergence angle α follow the following law: $$\left(\mathrm{0},\mathrm{05}\times {\mathrm{I}}_{\mathrm{s}}\right)/\tan \left(\mathrm{\alpha }\right)\le \mathrm{The}\le \left(\mathrm{0},\mathrm{4}\times {\mathrm{I}}_{\mathrm{s}}\right)/\tan \left(\mathrm{\alpha }\right)\mathrm{.}$$

According to one aspect of the invention, said neck is a sonic neck. The convergent and the divergent are, for example, connected directly to one another at the neck.

According to a variant, the outlet orifice of the nozzle is at the level of the neck. Such a nozzle has less cleaning performance than the previous but remains interesting in that it also allows a reduction in the carrier fluid consumption.

The invention also relates to a nozzle of a projection device as described above.

• la figure 1 illustre de façon schématique un exemple de dispositif de projection conforme à l'invention,
• la figure 2 illustre en vue de coupe longitudinale une buse d'un dispositif conforme à l'invention.
• la figure 3 illustre de façon schématique un exemple de dispositif de projection qui n'est pas conforme à l'invention, partiellement coupé selon un plan de coupe longitudinale.

The invention is detailed below, accompanied by the appended drawings among which:

• the figure 1 schematically illustrates an exemplary projection device according to the invention,
• the figure 2 illustrates in longitudinal section view a nozzle of a device according to the invention.
• the figure 3 schematically illustrates an example of a projection device which does not conform to the invention, partially cut in a longitudinal sectional plane.

As illustrated in Figures 1 and 2 the invention relates to a device for blasting dry ice particles, for example dry ice, in particular for cleaning surfaces.

Said device comprises a gun 10, for directing a driving fluid driving said particles in a first direction, marked D1, and a projection nozzle 4, allowing the passage of said driving fluid, charged said particles. Said driving fluid is, for example, compressed air.

The gun 10 is provided, in particular, with a supply 1 of driving fluid, a supply 2 of liquid carbon dioxide and a chamber 3 for the formation of dry ice particles (not shown in FIG. figure 2 ). The nozzle 4 is connected to the gun 10, and projects, under the action of the driving fluid, the particles formed in the chamber 3.

In more detail, according to such an embodiment example, the working fluid enters the device through the supply 1 of the driving fluid and then charges the ice particles generated in the chamber 3, at the exhaust of said chamber. This forms a flow of motor fluid and ice particles that passes through the nozzle 4 to be projected on the part to be cleaned.

According to the invention, said device is configured to orient the fluid, charged with said particles, in at least one other direction, marked D2, upstream of a neck 6 of the nozzle 4, according to the direction of flow of the driving fluid. In this way a deviation of the particle flow is obtained while limiting the losses of charges. For example, the angle between said first direction D1 and said other direction D2 is about 45 °.

The nozzle 4 comprises a convergent 8, intended to be located upstream of the neck 6 in the direction of flow of the driving fluid, and said device is configured to orient the fluid in the direction D2 upstream of said convergent 8.

As illustrated in the accompanying figures, it is the nozzle 4 which is configured to deflect the driving fluid, charged with said particles, in the direction D2.

For this, the nozzle 4 comprises a deflection portion 22, adapted to modify the path of said driving fluid, charged with said particles, of said first direction D1 in the direction D2, said deflection portion 22 being located upstream of the neck 6.

The nozzle 4 comprises a convergent 8 and said deflection portion 22 is situated at the level of said convergent 8.

The nozzle 4 comprises, for example, a portion 23 of constant section, intended to be located upstream of the convergent 8 in the direction of flow of the driving fluid, said portion 23 of constant section being able to guide the driving fluid, charged said particles, in said first direction D1.

Said portion 23 of constant section is here connected to the convergent by a plane 24, inclined with respect to the direction D1 and orthogonal to the direction D2. The portion of the nozzle 4 located downstream forms an acceleration portion.

As illustrated in the various figures, according to an advantageous embodiment of the invention, said nozzle 4 comprises a divergent 7 allowing an acceleration of said driving fluid in the direction D2.

Said divergent 7 extends, for example, between the neck 6 and an outlet orifice of the nozzle 5. The neck 6 and said outlet 5 of the nozzle 4 are, for example, orthogonal to the direction of the driving fluid, charged with said particles.

The ratio between the surface of the neck 6 and the surface of said outlet orifice 5 of the nozzle is, for example, greater than 0.2, especially 0.5, in particular 0.73. It will be, for example, less than 0.9. The applicant has indeed found that such a size choice allows an adequate acceleration of the particles for reduced consumption of motor fluid. Said surface ratio may be, for example, between 0.8 and 0.9.

Said divergent 7 has, for example, a rectangular section. The length l of said section increases linearly and has a substantially constant width or height, from the neck 6 to the outlet orifice 5 of the nozzle 4. It is, in particular a configured width or height to the size of the particles formed. It will thus be possible to use a width or height less than 2 mm, for example of the order of 1.2 or 1.3 mm.

The nozzle 4 comprises, for example, a portion 23 of constant section, intended to be located upstream of the convergent 8 in the direction of flow of the driving fluid, said portion 23 of constant section being able to guide the driving fluid, charged with said particles in said first direction D1.

Said portion 23 of constant section is here connected to the convergent by a plane 24, inclined with respect to the direction D1 and orthogonal to the direction D2. The portion of the nozzle 4 located downstream forms an acceleration portion.

That being so, according to a variant not illustrated, the nozzle may comprise a bent portion upstream of its convergent, or even upstream of a portion of constant section of the nozzle, connected to said convergent.

As illustrated in the various figures, according to an advantageous embodiment of the invention, said nozzle 4 comprises a divergent 7 allowing an acceleration of said driving fluid in the direction D2.

Said divergent 7 extends, for example, between the neck 6 and an outlet orifice of the nozzle 5. The neck 6 and said outlet 5 of the nozzle 4 are, for example, orthogonal to the direction of the driving fluid, charged with said particles.

The ratio between the surface of the neck 6 and the surface of said outlet orifice 5 of the nozzle is, for example, greater than 0.2, especially 0.5, in particular 0.73. It will be, for example, less than 0.9. The applicant has indeed found that such a size choice allows an adequate acceleration of the particles for reduced consumption of motor fluid. Said surface ratio may be, for example, between 0.8 and 0.9.

Said divergent 7 has, for example, a rectangular section. The length l of said section increases linearly and has a substantially constant width or height, from the neck 6 to the outlet orifice 5 of the nozzle 4. It is, in particular a configured width or height to the size of the particles formed. It will thus be possible to use a width or height less than 2 mm, for example of the order of 1.2 or 1.3 mm.

The neck 6 here has a rectangular section, one of the dimensions of which corresponds to the width or height of the diverging portion 7.

Said divergent also has a divergence angle α of about 6 ° to maintain a substantially straight stream at the nozzle outlet. As a variant, it could be an angle greater than 7 °, making it possible to obtain an enlargement of the flow at the outlet of the nozzle.

More precisely, said divergent portion 7 may have a length L of said nozzle 4, measured between the neck 6 and the outlet orifice 5 of said nozzle 4, a length 1 _S of the divergent section at said outlet 5 of the nozzle and an angle of divergence α according to the following law: $$\left(\mathrm{0},\mathrm{05}\times {\mathrm{I}}_{\mathrm{s}}\right)/\tan \left(\mathrm{\alpha }\right)\le \mathrm{The}\le \left(\mathrm{0},\mathrm{4}\times {\mathrm{I}}_{\mathrm{s}}\right)/\tan \left(\mathrm{\alpha }\right)\mathrm{.}$$

In particular, L may have as upper limit: (0.1 x _S ) / tan (α).

The outlet orifice 5 of the nozzle is in the form of a slot. This may have a height of less than 2 mm, in particular of the order of 1.2 or 1.3 mm and / or a length of between 10 and 50 mm, in particular between 20 and 50 mm.

According to another embodiment, not shown, said divergent has a circular section. In other words, the divergent is frustoconical. Said neck may then have a circular section. The angle of divergence may be of the order of 6 ° or greater than 7 °, with the same effects as those described above. The convergent will then also be circular and the bent portion conforming to the information will be either at the nozzle, upstream of the neck, or upstream of said nozzle.

By way of example, the divergents 7 of the nozzles 4 according to the invention have a length, measured between the neck and the outlet orifice of the nozzle, of less than 200 mm, in particular of 50 mm. It may be, in particular, a length of less than 10 mm for nozzles having an angle of divergence greater than 7 °.

In the accompanying figures, the convergent 8 and the divergent 7 are connected directly to one another at the neck 6. In other words, the neck 6 is a simple plane. Alternatively, the neck 6 may have a non-zero length.

In another variant, not shown, the nozzle does not include diverging. Its outlet is at the level of his collar. The acceleration obtained will thus be limited to that offered by the sonic collar, which may however be sufficient and even more favorable, especially for the cleaning of lightly soiled and / or particularly fragile surfaces.

That being so, said neck 6 is a sonic neck and will provide at the inlet of the nozzle 4 an absolute pressure of, for example, between 4 and 16 bar, especially between 4 and 6 bar.

Said nozzle comprises, for example, a body 30 defining said convergent 7, said neck 6 and / or said divergent 8, said body being optionally bent.

Claims (5)

1. Device for spraying particles of dry ice, in particular for cleaning surfaces, comprising a gun (10) for orienting a drive fluid driving said particles in a first direction, and a spray nozzle (4) allowing the passage of said drive fluid loaded with said particles, said nozzle (4) comprising a neck (6) and comprising a convergent device (8), located upstream of the neck and connected to said neck, said device being configured to orient the fluid loaded with said particles in at least one other direction upstream of the neck (6) according to the direction of flow of the drive fluid, the device being characterised in that the nozzle (4) is configured to divert the drive fluid loaded with said particles in the other direction or directions, as follows:

   - the nozzle (4) comprises a diversion portion (22) able to modify the path of said drive fluid loaded with said particles from said first direction into said other direction or directions, said diversion portion (22) being situated upstream of the neck (6);

   - and said diversion portion (22) is located at least partially level with said convergent device (8).
2. Device according to claim 1, wherein the nozzle (4) comprises a portion (23) with a constant cross-section intended to be situated upstream of the convergent device (8) in the direction of flow of the drive fluid, said portion with a constant cross-section (23) being able to guide the drive fluid loaded with said particles according to said first direction.
3. Device according to claim 1 or 2, characterised in that the nozzle further comprises a divergent device (7) extending between the neck (6) and an outlet orifice (5) of the nozzle.
4. Device according to claim 3, characterised in that the convergent device (8) and the divergent device (7) are directly connected to each other at the level of the neck (6).
5. Device according to one of claims 1 to 3, characterised in that the neck (6) has a non-zero length.

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