EP1114287B1 - Snowmaker - Google Patents

Abstract

The invention concerns a snowmaker including a hollow body (1) comprising a mixing and expansion chamber (2) defined by a peripheral wall (3) and communicating with outside through a ring-shaped coaxial outlet (4) around a central core (26). Water is introduced under pressure into the mixing and expansion chamber (2) through a plurality of helical ducts (6, 7) peripherally distributed about the longitudinal axis (I-I) to inject water along the peripheral wall (3) with a rotating motion. The pressurised air is introduced in the mixing and expansion chamber (2) in a central zone in one or several jets directed obliquely towards the peripheral wall (3) through a plurality of divergent air passages (11, 12). Such a snowmaker structure enables to produce quality snow from water and air at a lower pressure then in known snowmaker structures.

Description

The present invention relates to snow cannons for production of artificial snow by spraying a mixture air and water.

The development of winter sports has given birth, since a few years, the need to produce artificial snow to charge or recharge the ski slopes during the periods insufficient snow.

To date, we have developed three main families snow cannons for the production of artificial snow.

According to the first family, there is sufficient height above the ground, at the end of a pole, at least one nozzle air spray and an adjacent water spray nozzle.

Air and water mix in the atmosphere and form fines droplets that turn to snow before reaching the ground.

According to the second family, water spray nozzles project fine droplets into an air flow produced by a fan.

According to the third family, a two-fluid cannon has a mixing chamber in which air and water are sprayed, and the mixture leaves the mixing chamber through an orifice exit. This third family is for example illustrated by the document EP 0 018 280. In such a two-fluid gun, a hollow body includes a mixing chamber bounded by a peripheral wall coaxial and communicating with the outside through an outlet axial. Air intake means inject compressed air in the mixing chamber. Water intake means inject pressurized water in the mixing chamber. The bedroom mixture is an elongated tube, with a section significantly smaller than the section of the air supply and water supply pipes.

In this third family of two-fluid cannon, the document DE 29 41 052 A teaches to mix air and water in a mixing and compression chamber limited by two walls Conical interior and exterior converging coaxial. By their converging conical shape, the walls of the mixing chamber gradually compress water and air during mixing. Water is injected in several peripheral jets, according to a rotary movement. Air is injected from the inner wall conical of the mixing and compression chamber, in several jets in substantially longitudinal directions. Bedroom mixture is connected directly to the outlet, by its area of smaller section, without additional shrinkage.

The documents FR 2 376 384 A and JP 06 074627 A teach also to mix air and water in a conical chamber of mixing and compression.

In document EP 0 084 186 A, water enters a mixing chamber in an evenly distributed annular flow around the axis, and receives divergent air jets. The mixture is abruptly compressed by an annular flange engaged in the exit passage.

The devices of the first family, ensuring a high spraying at the end of a pole, need an inlet air pressure of 8 to 10 X 10 ⁵ Pa, and a water pressure of at least 16 to 20 X 10 ⁵ Pa. Spraying at height often leads to dispersing the snow outside the runway surface to be recharged, in the event of wind, even a weak one. The support structure necessary to hold the pole leads to a unitary installation whose weight is generally greater than 100 kilograms.

The second family fan gun devices can deliver 400 to 800 liters of water per minute for a unit installation weight of 400 to 1000 kilograms. These devices also require an inlet water pressure of between 16 and 20 X 10 ⁵ Pa approximately, as well as an electrical connection of 20 to 50 kilowatts. It is therefore necessary to provide expensive power cables to bring the energy to the snow production site.

Two-fluid guns of the type of that of documents EP 0 018 280, DE 29 41 052 A, FR 2 376 384 A, JP 06 074627 A or EP 0 084 186 A, also need a significant, higher water pressure. at 10 X 10 ⁵ Pa. The inlet air pressure must be of the order of 8 X 10 ⁵ Pa. Otherwise, the production of snow is faulty and the cannon mainly spits droplets of liquid water.

Thus, all these known devices require a large infrastructure, most often a pumping station with high pressures at the start to guarantee a pressure of 8 to 16 × 10 ⁵ Pa at the top of the tracks. The pipes in which the fluids flow must hold pressures of more than 40 X 10 ⁵ Pa on average, which makes them heavy and expensive to purchase and to set up. The guns themselves are also heavy and bulky, difficult to transport along rugged ski slopes.

Compressed air production devices capable of achieve the pressures necessary for the guns currently used are relatively expensive, because the pressures are higher than general purpose compressors used on construction sites to supply jackhammers.

There is therefore a permanent need for a device for production of artificial snow that can work with reduced air and water pressures, which is of a weight and reduced dimensions to facilitate its transport to the snow producing areas along the ski slopes.

The problem proposed by the present invention is therefore to design a new snow cannon structure to produce good quality snow from more pressure low air and water at the entrance, so as to be satisfied with a lighter air and water production infrastructure under pressure, and so as to use transport pipes lighter and less expensive air and water.

The invention results from the surprising observation according to which we can produce artificial snow from lower air and water pressures due to shape special air and water mixing and expansion chamber, larger diameter, in which we create a maximum of turbulence while undergoing a reduced pressure drop, and remove the mixture through a reduced section passage after a progressive compression.

To achieve these objects, this invention provides a snow cannon for producing snow artificial spraying of air and water, comprising a hollow body having an oriented mixing chamber along a longitudinal axis, limited by a peripheral wall lateral and communicating with the outside via an exit passage front, having means for admitting water to inject water under pressure in the mixing chamber in one or more streams preferential directives in the peripheral zone of the mixing along the peripheral wall and in a movement rotatable around the longitudinal axis of the mixing chamber, and having shaped air intake means for injecting air compressed into the mixing chamber from the central area of mixing chamber, the means of admission of air being shaped to inject air in the form of one or several air jets each directed to cut off one of said flows preferential water directives, and the mixing chamber comprising an upstream expansion section followed by a downstream section of compression, the upstream expansion section communicating with the water intake means and with the air intake means and having a cross section greater than that of the means water and air intake to allow expansion of fluids during their mixing, the downstream compression section having a section which is gradually reduced towards the exit to compress the mixture and lead it to the passage of exit.

Thanks to such a mixing chamber structure, the two-fluid gun according to the invention can be compact and light, according to a weight of 2 to 3 kilograms, which is easily moved. Such a gun is capable of operating at variable flow rates as a function of the outlet passage section, and with water inlet pressures of the order of 4 × 10 ⁵ Pa and an air pressure of order of that produced by the usual site compressors for supplying jackhammers. Under certain conditions, it is possible to snow with an inlet water pressure which can go down to around 3 X 10 ⁵ Pa. The compressed air pressure is slightly higher than that of water.

According to an advantageous embodiment, in the section upstream of expansion of the mixing chamber, the peripheral wall lateral is substantially cylindrical.

Also, according to an advantageous embodiment favoring obtaining snowflakes at the outlet, we can predict that, in the upstream expansion section of the mixing chamber, the air intake means injects air in the form of one or several jets directed obliquely towards the peripheral wall.

Preferably, in the downstream compression section, the lateral peripheral wall forms a frustoconical narrowing connecting to the outlet passage.

It is also advantageous to provide that the passage of outlet is an annular orifice.

Thanks to such an annular form of outlet orifice, the mixture of air and water comes out through the orifice in tubular form and in rotation, and it pushes the outside air forward by inducing a central depression which favors the entry of drafts outside towards the center. This likely favors the splitting of the droplets and causes a better exchange thermal with outside air and droplets. The mixture is cools faster and freezes quickly before touching the ground.

Also, as the mixture changes pressure between the mixing chamber and the outside, the air expands quickly and separates the parts of water which are close to it. This favors likely the formation of snowflakes.

According to one embodiment, the water intake means comprise a plurality of helical channels distributed in periphery around the longitudinal axis, and the helical canals can be connected, upstream, to an annular chamber of water distribution communicating with a peripheral water inlet.

According to one embodiment, the air intake means may include a plurality of air channels. Air channels can advantageously be divergent to direct the air obliquely towards the peripheral wall.

In practice, the air channels can communicate with the mixing chamber by injection orifices distributed in a crown of a posterior frontal wall. This favors appreciably the formation of snowflakes at the outlet, presumably due to the vortex expansion of fluids during their mixing in the upstream section of the mixing chamber.

According to a particular embodiment, provision is made for adjustment plate with an annular series of holes through, the adjustment plate coming to bear against the wall posterior frontal and can be pivoted around the axis longitudinal between a fully open position in which each air channel outlet is opposite a hole through the adjustment plate, and shutter positions partial in which the adjustment plate is slightly rotated around the longitudinal axis to offset at least partially the plate holes in relation to the holes of outlet of the air channels. This creates air turbulence entering the mixing chamber, and also adjust the air flow. Indeed, in some cases, it is useful to be able decrease the air flow which arrives in the mixing chamber to reduce the risk of freezing when leaving the room.

Preferably, the exit passage is limited internally by the central core and is externally limited by an internal radial annular lip.

According to an advantageous embodiment, the central core is elongated longitudinally and is adjustable in position longitudinal along the longitudinal axis, and its section transverse is variable longitudinally. We can thus adjust to a certain extent the diameter of the mixing jet to a few centimeters from the outlet, to adapt to external conditions of humidity and temperature to optimize the quality of the to set the shooting distance.

In this case, depending on one possibility, the central core can additionally comprise several external radial annular ribs, of different diameters, separated by a frustoconical section.

As an alternative, the central core can advantageously be conical, allowing continuous adjustment of the cross section of the exit.

An additional function of the central core can be obtained by providing a central core in the form of a nut reversible engaged by screwing and selectively locked in position axial on an axial threaded rod of the body. By the same nucleus central, we can thus significantly modify the shape of the passage of exit. The larger the section of the outlet passage, the greater the possible flow will be high for a given fluid pressure at entry. Depending on the shape of the passage between the mixing chamber and the output it is possible to create an average speed of outlet of air and water masses, of divergent shape or convergent, and thus adapt the spray for training optimized snow and shooting distance setting.

For a given exit passage form, it is naturally possible to modify the flow by varying the inlet fluid pressure. Also, for pressure at given entry, you can choose the form of the exit passage more suitable for producing quality snow according to external humidity and temperature conditions.

• la figure 1 est une vue de côté en coupe longitudinale d'une structure de canon à neige selon un mode de réalisation de la présente invention ;
• la figure 2 est une vue en bout du canon à neige de la figure 1 ;
• la figure 3 est une vue d'avant en coupe selon le plan A-A de la figure 1 ; et
• la figure 4 est une vue de dessus en coupe horizontale partielle selon le plan B-B de la figure 1.

Other objects and advantages of the present invention will emerge from the following description of particular embodiments, made in relation to the attached figures, among which:

• Figure 1 is a side view in longitudinal section of a snow cannon structure according to an embodiment of the present invention;
• Figure 2 is an end view of the snow cannon of Figure 1;
• Figure 3 is a front sectional view along the plane AA of Figure 1; and
• FIG. 4 is a top view in partial horizontal section along the plane BB of FIG. 1.

In the embodiment illustrated in the figures, a snow cannon according to the invention comprises an elongated hollow body 1, for example generally cylindrical, having a mixing chamber 2 limited by a peripheral wall 3 and communicating with the exterior by a front exit passage 4.

The hollow body 1 generally develops along an axis longitudinal I-I, the peripheral wall 3 is of revolution and coaxial around the longitudinal axis I-I, and the outlet passage 4 is arranged symmetrically along the longitudinal axis I-I.

However, without significant loss of efficiency, provide an outlet passage 4 offset from the axis I-I, not symmetrical, and provide a mixing chamber 2 which is not of revolution.

Mixing chamber 2 includes an upstream section expansion 201, having a substantially cross section greater than that of exit passage 4, and followed by a section downstream compression 202. The downstream compression section 202 has a reduced cross section, and is connected to said audit outlet passage 4 forming a constriction 5, for example a tapered narrowing as illustrated in Figure 1. In the upstream expansion section 201, illustrated in the figures, the wall device 3 is cylindrical.

In the mixing chamber 2, the water is introduced by water intake means comprising a plurality of channels helical like channels 6, 7, 8, 9 and 10, distributed regularly on the periphery around the longitudinal axis I-I. Each channel injects the water in a jet, creating in the mixture 2 a directive preferential flow occupying part only from the cross section of the mixing chamber. The circulation of fluids in a chamber cross section mixing thus exhibits strong velocity gradients. So the channels 6-10 constituting the means for admission of pressurized water are shaped to inject water under pressure according to a plurality of preferential directive water flows in the zone device of the mixing chamber 2 along the wall peripheral 3 and in a rotary movement around the axis longitudinal I-I of the mixing chamber 2. For example, the channels 6-10 consist of helical peripheral grooves distributed around a central cylindrical piece forming a intermediate transverse wall 21 and engaged in a tube forming the peripheral wall 3.

Compressed air is introduced into mixing chamber 2 by air intake means comprising a plurality of channels air such as channels 11, 12, 13, 14, 15 and 16, distributed in the central zone of the hollow body 1 around the longitudinal axis I-I. For example, as shown in Figure 1, the air channels 11-16 are divergent and form an angle with the longitudinal axis I-I about 15 degrees, gradually moving away from the axis longitudinal I-I as they get closer to the mixture 2. Each air channel 11-16 is positioned and shaped to direct an air jet so that it cuts off one of the streams preferential water directives.

Thus, the air intake means constituted by the air channels 11-16 are shaped to inject compressed air from the central zone of mixing chamber 2 according to one or several air jets directed obliquely towards the peripheral wall 3. In this way, the jets of compressed air enter the preferential directional flows of rotating water in the upstream section expansion 201 of the mixing chamber 2.

Upstream, the helical water intake channels 6-10 are connect to an annular water distribution chamber 17, externally limited by an external cylindrical wall 18 extending backwards the peripheral wall 3 of the mixture 2, and internally limited by a cylindrical wall inner 19. The inner cylindrical wall 19 is connected to the outer cylindrical wall 18 upstream by a crown 20 posterior, and downstream by a transverse wall intermediate 21 comprising the helical channels 6-10 and the divergent channels 11-16. In Figure 4, the cylindrical walls outside 3 and 18 are cut along plane B-B of FIG. 1, while the intermediate transverse wall 21 is not cut to reveal, according to its periphery, the channels helical such as helical channels 6 and 8.

Upstream, the air channels 11-16 are connected to a axial air supply pipe 22, externally limited by the inner cylindrical wall 19.

The axial air intake manifold 22 communicates with a central air inlet 23, while the annular chamber of water distribution 17 communicates with a peripheral water inlet 24.

The upstream expansion section 201 of the mixing chamber 2 communicates with the water intake means and with the means air intake, and has a higher cross section to that of the water and air intake means, to authorize expansion of fluids during mixing.

In the embodiment illustrated in the figures, the chamber 2 is limited upstream by a front wall posterior 203, which is for example formed by the wall intermediate transverse 21 itself.

As can be seen in particular in FIG. 3, the channels of air 11-16 communicate with the mixing chamber 2 by means of injection ports distributed in a coaxial ring on the posterior front wall 203.

According to an embodiment as illustrated in the figure 1, an adjustment plate 25, pierced with an annular series of holes through, bears against the coaxial crown of the wall rear posterior 203. The adjustment plate 25 can be pivoted around the longitudinal axis I-I between an open position complete in which each air channel outlet 11-16 is opposite a through hole of substantially the same section of the adjustment plate 25, and of the partially closed positions in which the adjustment plate 25 is slightly pivoted around the longitudinal axis I-I to offset at least partially the plate holes in relation to the holes of air channel outlet 11-16. The adjustment plate 25 thus allows both create turbulence in the air entering the mixing chamber 2, and adjust the air flow.

In the embodiment of Figures 1 and 2, the passage outlet 4 is an annular orifice, around a core central 26. Alternatively, one could use for example a plurality of outlet orifices, distributed in an annular crown, or in matrix.

In the illustrated embodiment, the central core 26, engaged in outlet passage 4, includes a first rib external radial annular 27, and a second annular rib external radial 28 of diameter greater than that of the first external radial annular rib 27 from which it is separated by a tapered section 29.

The central core 26 is preferably adjustable in position longitudinal along the longitudinal axis I-I. For example, like illustrated in FIG. 1, the central core 26 is in the form of a reversible nut engaged by screwing and selectively locked in axial position on an axial threaded rod 30 of the body 1.

For example, the axial rod 30 is screwed into a bore axial 31 threaded through the intermediate transverse wall 21. By more or less important screwing of the central core 26 on the rod axial 30 threaded, the longitudinal position of the core is adjusted central 26 relative to an internal radial annular lip 32 of the body 1 which externally limits the outlet passage 4.

Thus, the outlet passage 4 is externally limited by the internal radial annular lip 32 of the body 1, and internally through the central core 26. Depending on the position of the core central 26 along the longitudinal axis I-I, it is thus possible change the shape of exit passage 4. For example, in the position illustrated in FIG. 1, the outlet passage 4 is substantially limited by the internal radial annular lip 32 and by the first external radial annular rib 27 of the core central 26.

Preferably, the internal radial annular lip 32 is an edge bounded by two faces forming an angle between them less than about 110 °. This promotes abrupt relaxation vortex of outgoing fluids, for the formation of flakes of snow. This effect is further increased in the presence of a rib external radial annular 27 of the central core 26 facing the lip internal radial annular 32.

If we return the central core 26, we can achieve a outlet passage 4 of smaller section, limited by the lip internal radial annular 32 and by the second annular rib external radial 28 of the central core 26.

In the embodiment illustrated in Figure 1, the rod axial 30 also serves to hold the adjustment plate 25: the rod 30 passes through a central hole in the adjustment plate 25, and the adjustment plate 25 is kept pressed against the wall transverse intermediate 21 by a tightening nut 33 screwed on the axial rod 30.

The present invention is not limited to the modes of which have been explicitly described, but it includes the various variants and generalizations contained in the field of the claims below.

Claims (15)

1. A snowmaker for producing artificial snow by spraying a mixture of air and water, including a hollow body (1) having a mixing chamber (2) oriented along a longitudinal axis (I-I), delimited by a lateral peripheral wall (3) and communicating with the exterior via a frontal outlet passage (4), with water entry means for injecting one or more directional preferred flows of water under pressure into the mixing chamber (2) in a peripheral area of the mixing chamber (2) along the peripheral wall (3) and with a rotary movement around the longitudinal axis (I-I) of the mixing chamber (2), and with air entry means (11-16) conformed to inject compressed air into the mixing chamber (2) from the central area of the mixing chamber (2), the air entry means (11-16) being conformed to inject the air in the form of one or more air jets each directed to intersect one of said directional preferred flows of water, and the mixing chamber (2) including an upstream expansion section (201) followed by a downstream compression section (202), the upstream expansion section (201) communicating with the water entry means and with the air entry means and having a cross section larger than that of the water and air entry means to authorize expansion of the fluids as they are mixed, the downstream compression section (202) having a section that is progressively reduced in the direction of the outlet to compress the mixture and to conduct it to the outlet passage (4).
2. A snowmaker according to claim 1, characterized in that the lateral peripheral wall (3) is substantially cylindrical in the upstream expansion section (201) of the mixing chamber (2).
3. A snowmaker according to either claim 1 or claim 2, characterized in that the air entry means (11-16) inject air in the form of one or more jets directed obliquely towards the peripheral wall (3) in the upstream expansion section (201) of the mixing chamber (2).
4. A snowmaker according to any of claims 1 to 3, characterized in that the lateral peripheral wall (3) forms a frustoconical constriction (5) connected to the outlet passage (4) in the downstream compression section (202).
5. A snowmaker according to any of claims 1 to 4, characterized in that the outlet passage (4) is an annular orifice.
6. A snowmaker according to any of claims 1 to 5, characterized in that the water entry means include helicoidal channels (6-10) connected at the upstream end to an annular water distribution chamber (17) communicating with a peripheral water inlet (24).
7. A snowmaker according to any of claims 1 to 6, characterized in that the air entry means include a plurality of air passages (11-16) distributed around the longitudinal axis (I-I) in the central area of the hollow body (1).
8. A snowmaker according to claim 7, characterized in that the air passages (11-16) are connected at the upstream end to an axial air feed tube (22) communicating with a central air inlet (23).
9. A snowmaker according to either claim 7 or claim 8, characterized in that the air passages (11-16) communicate with the mixing chamber (2) via injection orifices distributed in a ring on a posterior frontal wall (203).
10. A snowmaker according to claim 9, characterized in that it includes an adjustment plate (25) pierced with an annular series of through-holes, the adjustment plate (25) bearing against the posterior frontal wall (203) and being able to pivot about the longitudinal axis (I-I) between a completely open position in which each outlet orifice of an air passage (11-16) is opposite a through-hole in the adjustment plate (25), and partially closed positions in which the adjustment plate (25) is pivoted slightly about the longitudinal axis (I-I) to offset the holes in the plate at least partly relative to the outlet orifices of the air passages (11-16).
11. A snowmaker according to any of claims 1 to 10, characterized in that the outlet passage (4) is delimited internally by a central core (26) and externally by an inner radial annular lip (32).
12. A snowmaker according to claim 11, characterized in that the inner radial annular lip (32) is an edge limited by two faces with an angle between them of less than 110°.
13. A snowmaker according to either claim 11 or claim 12, characterized in that the central core (26) is elongate longitudinally, and its longitudinal position along the longitudinal axis (I-I) is adjustable, and its cross section varies longitudinally.
14. A snowmaker according to claim 13, characterized in that the central core (26) further includes a plurality of external annular radial ribs (27, 28), with different diameters, separated by a frustoconical section (29).
15. A snowmaker according to either claim 13 or claim 14, characterized in that the central core (26) is a reversible nut screwed onto and adapted to be selectively immobilized axially on an axial threaded rod (30) of the body (1).

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