FR2844211A1 - Agricultural spray atomizer, for dispersing fungicides and weed killer, has diffusion surface defined on conical rotor in gas flow and with drop forming ridge - Google Patents

Abstract

The agricultural spray atomizer has a diffusion surface (30) positioned in a gas flow (26) and on which a liquid can flow downwardly towards a ridge (32) at which the liquid forms droplets carried by the gas flow. The diffusion surface is rotated and can be conical or frusto-conical. The diffusion surface can be rotated by the action of the gas flow. An Independent claim is also included for an agricultural vehicle using the atomizer.

Description

LIQUID SPRAYING DEVICE AND MACHINE

  AGRICULTURAL EQUIPPED WITH AT LEAST ONE DEVICE

  The present invention relates to a device for spraying liquid, in particular a crop or soil treatment liquid, as well as to an agricultural machine, called a sprayer, equipped with at least one device according to the invention. In agriculture, especially in the vineyard, spraying devices are used to spread a crop liquid on the crops or on the soil.

  treatment, such as a phytosanitary liquid, weedkiller or other.

  The treatment is all the more effective as the surface to be treated is covered

  uniformly by the liquid.

  In return, it is necessary to reduce the amount of product used by

  surface unit taking into account the cost of treatment products.

  To obtain the best compromise, the treatment liquid should be sprayed in the form of small droplets so as to obtain a

  the largest area treated for a given quantity of liquid.

  There are many devices, called sprayers, that allow the

  spraying of a treatment liquid.

  A first category of devices includes ejection nozzles. In this case, a liquid is propelled via a nozzle in the form of a fine slit. Apart from the fact that it is necessary to use a pump to propel the liquid through the nozzle, this mode of ejection is not satisfactory since the liquid is propelled in the form of a jet consisting of droplets of a diameter

relatively large.

  A second category of devices uses an air flow to transport the droplets. The present invention relates more precisely to this type of apparatus. Existing devices include a fixed surface arranged in the air flow, with an edge on the downstream side of the flow, onto which the treatment liquid is sprayed so as to create on said surface a coating of liquid which progresses towards the edge and is then entrained in the form of 10 droplets by the air flow. As a variant, the liquid is not projected against the surface but it diffuses over the surface, being entrained by the venturi effect. Even if this embodiment makes it possible to obtain droplets of a diameter smaller than the previous embodiment, it is not satisfactory because it does not allow the creation of droplets small enough to

  optimize the treatment both in terms of quality and quantity.

  Also, the present invention aims to overcome the drawbacks of the devices of the prior art by proposing a spraying device capable of generating micro-droplets of a diameter smaller than those generated by the existing devices, said device being moreover simple and reliable design. To this end, the subject of the present invention is a device for spraying a liquid comprising a diffusion support, arranged in a gas flow, with at least one diffusion surface on which the liquid to be sprayed is likely to flow. , having an edge at which the droplets entrained by the gas flow are formed, characterized in that the surface of

diffusion is rotated.

  This arrangement makes it possible to increase the relative speed between the liquid to be sprayed and the gas flow, which contributes to reducing the size of the droplets.

  Advantageously, the diffusion surface is conical or frustoconical, widening in the direction of flow of the gas flow, the widest terminal part constituting the edge. According to this characteristic, this type of shape makes it possible to obtain a length

  longer edge for a given size.

  According to a preferred embodiment, the diffusion support has a funnel shape with a flared part, the inner surface of which constitutes the diffusion surface, the supply of liquid to be sprayed taking place at the level

from the top of said flared shape.

  According to another characteristic, the spraying device comprises drive means for rotating the diffusion support using

the gas flow.

  According to another characteristic, the spraying device comprises a bearing

  hydrodynamic ensuring the guidance of the diffusion support.

  According to another characteristic, the spraying device comprises

  means for disturbing the gas flow upstream of the diffusion surface.

  According to another characteristic, the spraying device comprises means for controlling the flow of liquid to be sprayed, arranged at a level

  supply duct, comprising a valve capable of occupying two extreme positions, a first so-called open position, in which said valve does not close the supply duct and lets the liquid pass through, and a second so-called closed position, in which it closes the supply conduit 25 and prevents the flow of liquid.

  According to one embodiment, the means for controlling the flow of liquid to be sprayed comprise return means which tend to keep the valve in the closed position, the valve translating as a function of the pressure difference between the downstream pressure Ps and the pressure downstream Pi of the liquid inside the

supply duct.

  Other characteristics and advantages will emerge from the description which represents a preferred embodiment, description given as

  example only, with reference to the accompanying drawings which represent: Figure 1, an elevational view of an agricultural machine called a sprayer, equipped with the spraying device according to the invention, Figure 2, a schematic section of a device illustrating the principle of the invention, - Figure 3, a longitudinal sectional view of an embodiment, - Figures 4A and 4B, sections of the device illustrating the valve respectively in the open position and in the closed position, - Figure 5, a view in longitudinal section of a first alternative embodiment, and - Figure 6, a view in longitudinal section of a second alternative embodiment.

  A sprayer 10 is used in particular in agriculture to spread in the form of fine droplets a treatment liquid, such as a phytosanitary product of the fungicidal, bactericidal or other type, over an area to be treated, for example crops or the soil.

  According to the mode illustrated in Figure 1, a sprayer 10 can be attached to a rolling chassis 12 capable of being connected via a hitch 14 to a tractor not shown. Alternatively, a sprayer can be attached directly to a

  motorized vehicle such as a straddle or the like.

  The sprayer 10 comprises a reservoir 16 in which the treatment liquid is stored, means 18 for generating a gas flow, in particular of air, at least one conduit 20 for channeling the air flow and directing it towards the area to be treated , as well as a spray device 22 in the air flow,

  preferably at each end of the duct (s) 20.

  The reservoir 16, the means 18 for generating an air flow as well as the conduits

  are not described in more detail because within the reach of ordinary skill in the art.

  The spraying device 22 is now described with reference to FIGS. 2 and 3. This device comprises a sleeve 24, disposed at the end of a duct 20, in which the air flow 26 flows as well as a support diffusion 28, arranged in the air flow 26, comprising a diffusion surface 30 on which is likely to flow the liquid to be sprayed, having an edge 10 32 downstream, at the level of which the droplets entrained by the air flow according to the invention, said diffusion surface 30 being rotated. For a given speed of the air flow, the rotation of the diffusion surface 30 makes it possible to increase the relative speed between the liquid to be sprayed at the edge 32 and the air flow and thus to obtain micro droplets of a

  smaller diameter than those obtained using existing devices.

  The diffusion surface 30 is preferably conical or frustoconical, widening in the direction of the flow of the air flow, the widest terminal part constituting the edge 32. This type of shape makes it possible to obtain a edge 20 32 of greater length, which also contributes to reducing the size of the

droplets from the start.

  The size of the droplets is already very small by the time they drop.

detach from said edge.

  According to a preferred embodiment, the diffusion support 28 has a funnel shape with a cylindrical part 34 and a flared part 36, the inner surface of said flared part 36 constituting the diffusion surface 30. The liquid supply to spraying takes place at the top of the flared shape 36, the liquid flowing at the level of the diffusion surface 30 in the direction of the edge 32 by the venturi effect. Alternatively, the outer surface of

  the flared part can constitute the diffusion surface 30.

  According to another characteristic of the invention, the spraying device comprises drive means 38 for rotating the diffusion support 28 using the air flow. According to a preferred embodiment, illustrated by FIG. 3, these drive means 38 are secured to the cylindrical part 34 of the diffusion support, and comprise a screw 40 having at its external surface at least one thread, the shape allows the assembly to be rotated by the air flow 26. By screw means any suitable shape capable of being rotated when it is arranged in an air flow to

  like a turbine, a propeller or the like.

  By way of example, a conical multi-threaded screw 40, length 125 mm, placed in an air flow with a speed of 100 km / h makes it possible to obtain a rotation speed 15 of 13,000 rpm.

  According to another characteristic of the invention, the screw / diffusion support assembly comprises a bore 42 in which is capable of accommodating an axis of rotation 44 substantially parallel to the air flow 26, a hydrodynamic bearing being provided between the screw / diffusion support assembly and axis 44. Advantageously, the liquid to be sprayed is used to obtain the hydrodynamic bearing. To this end, the axis 44 fixed and secured at each end by means of arms 46 to the sleeve 24 comprises a conduit 48 opening on the one hand, at the upstream end of said axis 44, outside of the screw / diffusion support assembly so as to be connected to a pipe 25 for supplying liquid to be sprayed, and on the other hand, at the level of the

  guiding said shaft in line with the screw / diffusion support assembly.

  be preferably, the axis 44 comprises at its peripheral surface, upstream, at least one decompression groove 50 to limit leaks and downstream

  at least one groove 52 in the form of a net so as to generate a micropump.

  According to another characteristic of the invention, means for disturbing the air flow 5 are arranged upstream of the diffusion surface 30. These means also contribute to reducing the size of the droplets. Advantageously, the screw 40 has a thread profile suitable for disturbing the air flow and

  limit the appearance of laminar flow at the edge 32.

  Therefore, the disturbances in the air flow ensure an additional division of the ejected droplets.

  According to another characteristic of the invention, the sleeve 34 has the shape of a nozzle. This shape combined with the swirling disturbed flow generated by the screw 40 makes it possible to wrap the droplets, to limit the phenomena of dispersion and the formation of large droplets at the surface of the sleeve 34.

  According to another characteristic of the invention, the spraying device comprises means 54 for controlling the flow of liquid to be sprayed, illustrated

by Figures 4A and 4B.

  Advantageously, the bore 42 used to house the axis of rotation 44 opens out at the top of the flared part 36 and serves as a conduit for supplying the spraying fluid which subsequently flows onto the diffusion surface 30 through

venturi effect.

  The means 54 for controlling the flow rate comprise a valve 56 capable of occupying two extreme positions, a first so-called open position, illustrated in FIG. 4A, in which said valve does not block the duct

  supply, in our case the end of the bore 42, and allows the liquid to pass, and a second so-called closed position, illustrated by FIG. 4B, in which it closes the supply duct and prevents the flow of liquid.

  The intermediate positions each correspond to a flow value varying from zero to a maximum value corresponding respectively to the positions

closed and open.

  According to a preferred embodiment, illustrated by FIGS. 4A and 4B, the end of the bore 42 comprises a chamfer or a machining forming a seat 58, the valve 56 slidingly mounted on the axis of rotation 44 having shapes suitable for cooperating with seat 58 so as to ensure

  sealing in the closed position.

  Preferably, means for operating the valve from one to the other of the 10 positions are provided and include return means 60, for example a spring, which tend to press the valve 56 against the seat 58. In this In this case, the valve 56 translates to the open position as soon as the downstream pressure Ps at the flared part becomes lower than the downstream pressure Pi of the liquid inside

of the supply duct.

  This pressure difference is preferably generated using the

  depression which is created inside the flared part 46 thanks to the air flow 26.

  Indeed, from a certain speed of the air flow, a vacuum is created at the flared part so that the downstream pressure Ps becomes lower than the

upstream pressure Pe.

  Thus, the flow rate of the liquid corresponding to a position of the valve is proportional to the value of the pressure difference more exactly to the value of the pressure Ps proportional to the speed of the air flow. This solution has the advantage of being very simple, of adjusting the flow rate to the air speed and of not

require no pump or motor.

  According to this embodiment, the means 54 for controlling the flow of the liquid

  can be adjusted by adjusting the calibration of the return means.

  Of course, the invention is not limited to the embodiment described but covers its variants. Thus, the means for driving the diffusion surface in rotation, means for disturbing the flow as well as means for controlling

  of the liquid flow can be changed in their form.

  In FIG. 5, another variant of the device 122 of the invention is shown, the elements taken from the previous variant being referenced by adding 100 to their reference. This device comprises a sleeve 124 in which flows an air flow 126, an axis 144 connected to said sleeve via at least one arm 146 and on which are mounted free in rotation a screw 140 and a diffusion surface 130, a conduit 148 formed in the axis 144 allowing the liquid to be brought into line with the diffusion surface 10. As before, the thread of the screw 140 makes it possible to drive in

  rotating the diffusion surface 130 and disturbing the air flow 126.

  Similarly, the diffusion surface 130 comprises a conical or frustoconical portion 136 ending in an edge 132 at the level of which the fine droplets are detached. Furthermore, as before, the conical shape 15 of the diffusion surface makes it possible to generate a vacuum which produces the flow of the liquid to be sprayed without it being necessary to provide a

  pump to generate the flow of liquid.

  In the same way, the axis 144 can comprise at its peripheral surface, upstream, at least one decompression groove 150, and downstream, at least one groove 152 in the form of a net.

  According to the embodiment shown in f igure 5, the means for controlling the flow rate are not shown and can be implemented by any

  suitable means such as valves.

  Depending on the case, the screw 140 and the diffusion surface 130 are rotatably mounted on the axis 144 by virtue of a hydrodynamic bearing and / or rolling means 162. According to a characteristic of this embodiment, the liquid to be sprayed is projected against the diffusion surface 130. For this purpose, the liquid flows from at least one conduit 164 which does not open out at the top 165 of the diffusion surface 130, as before, but offset with respect to said top so that the fluid does not diffuse from the conduit 164 to the diffusion surface 130 but is projected onto said surface 130 5 by centrifugal force so as to increase the fragmentation of the droplets. According to another characteristic of this embodiment, the device comprises a second conical or frustoconical diffusion surface 166 concentric with the first diffusion surface 130 and disposed inside said diffusion surface 130, the liquid to be sprayed s' flowing between said

surfaces 130 and 166.

  According to the embodiment described, the device comprises a first kinematic assembly constituted by the sleeve 124, the arms 146 and the axis 144, and a second kinematic assembly constituted by the screw 140, a first funnel-shaped element 168 comprising the first diffusion surface 130 and a second funnel-shaped element 170, coaxial with the first element,

  comprising the second diffusion surface 166.

  The second funnel-shaped element 170 comprises a flared part 172 of conical or frustoconical shape, the external surface of which constitutes the second diffusion surface 166 and a cylindrical part 174 with an internal bore 176 in which a part of the axis 144, a bearing 162 being disposed between the axis 144 and the element 170. At least one conduit 164 is formed at the level of the cylindrical part 174, opening on the one hand at the level of the external surface of the cylindrical part 174 substantially at the base of the flared part 172 and on the other hand at the level of the internal bore 176, a clearance being provided between the axis 144 and the element 170 to allow the flow of the

liquid to spray.

  i1 The first funnel-shaped element 168 also comprises a flared part 136 whose inner surface constitutes the first diffusion surface 130 and a cylindrical part 134 with an internal bore 178, said cylindrical part 134 being interposed between a shoulder 180 formed at level of the outer surface of the cylindrical part 174 of the second element 170 and a

  bore 182 formed at the end of the screw 140.

  According to this embodiment, the duct (s) 164 are offset with respect to the shoulder 180 so that the liquid cannot diffuse in the direction of the

  first diffusion surface 130 but is projected against said surface.

  In this case, part of the liquid flowing from the duct (s) 164 is projected against the first diffusion surface 130 while another part diffuses onto the second diffusion surface 166. By the centrifugal effect, the liquid flowing along the second diffusion surface 166 detaches from said surface to come to project against the first diffusion surface 15 130. The surface condition of the second diffusion surface 166 is adapted to allow the detachment of the liquid from this surface and limit the effects of capillarity. This second diffusion surface 166 makes it possible to increase the fragmentation and

  to further reduce the diameter of the projected droplets.

  In FIG. 6, a slightly modified variant is shown with respect to

  that of FIG. 5. The identical elements have the same references.

  Compared to the variant of FIG. 5, the guidance of the rotary screw elements / first diffusion surface / second diffusion surface relative to the axis

144 is obtained by two bearings.

  According to this variant, the conduit 148 is extended and opens out via orifices

  between the axis 144 and the cylindrical part 174, between the two bearings.

  As before, the conduits 164 are offset from the apex 165 of the first diffusion surface so that the fluid does not diffuse from the conduit 164 to the diffusion surface 130 but is projected onto said surface 130 thanks to centrifugal force so as to increase the

fragmentation of droplets.

  According to this variant, the duct 124 is extended by a terminal duct in the form of a nozzle, that is to say with a flared end 186. This terminal conduit 184 can translate relative to the conduit 124, as illustrated by the double arrow 188 so that the end 186 can be moved relative to

  the edge 132 of the diffusion surface 130.

  For this purpose, the terminal conduit 184 is fitted on the conduit 124 and can slide relative to the latter.

  Oblong holes 190 are provided to accommodate the ends of the arms 146 of

  so as to limit the travel of the terminal duct 184.

  This arrangement makes it possible to increase or reduce the size of the diffusion cone.

  Thus, if the end 186 is offset downstream in the direction of flow of the flow i5 relative to the edge 132, we obtain a diffusion cone with a smaller angle at the top than if the end 186 is shifted upstream, as

illustrated by figure 6.

  According to another characteristic of the invention, the diffusion surfaces 130, 166 may have suitable surface states, in particular very rough, so as to increase the bursting of the liquid in the form of micro-droplets.

  Compared to the prior art, it is not necessary to put the liquid under high pressure before projecting it onto a diffusion surface to obtain fine droplets. In general, the depression generated by the conical shape of the diffusion surfaces is sufficient to cause the liquid to flow through the conduit 25 148. in addition, one can only provide a low pressure pump to accompany the liquid towards the diffusion surfaces knowing that this pump

  has no effect on the micronization of droplets.

  Finally, this spraying device can be used in other fields when it is necessary to spray with a gas flow a liquid in the form of micro-droplets. It can be used to diffuse a liquid towards the

  low without drops of large diameter appearing.

  D In addition, given that the air flow is at a reduced range, it is possible to treat plants in strips such as vegetable plants without degrading them by blowing. As for the micronization obtained, it again allows

optimize treatments.

  The invention also covers the agricultural machine equipped with at least one of these 10 devices.

Claims (11)

  1. Device for spraying a liquid comprising a diffusion support (28, 128), disposed in a gas flow (26, 126), with at least one diffusion surface (30, 130) on which is likely to s' drain the liquid to be sprayed, having an edge (32, 132) at the level of which are formed the droplets entrained by the gas flow (26, 126), characterized in that at   at least one diffusion surface (30, 130) is rotated.   2. Spraying device according to claim 1, characterized in that   the diffusion surface (30, 130) is conical or frustoconical, widening in the direction of flow of the gas flow, the widest terminal part constituting an edge (32, 132).   3. Spray device according to any one of claims 1 to   2, characterized in that it comprises means (38, 138) for driving to rotate the diffusion support (28, 128) using the gas flow (26, 126). 4. Spray device according to claim 3, characterized in that the drive means (38, 138), secured to the diffusion support (28, 128), comprise a screw (40, 140) having at least one thread, the form   allows the assembly to be rotated by the gas flow (26, 126).   5. Spray device according to any one of claims 1 to 20 4, characterized in that it comprises means for projecting the liquid against the diffusion surface (130).   6. Spraying device according to claims 2 and 5, characterized in   that it comprises at least one conduit (164) from which the liquid to be sprayed flows offset from the top (165) of the diffusion surface (130) so that the liquid is projected by the centrifugal effect against said diffusion surface (130).   7. Spray device according to claim 5 or 6, characterized in that   that it includes a second diffusion surface (166).   8. Spray device according to claim 7, characterized in that the second diffusion surface (166) is conical or frustoconical, concentric with the first diffusion surface (130) and disposed inside said diffusion surface ( 130), the liquid to be sprayed flowing between said surfaces (130, 166). 9. Spray device according to claim 8, characterized in that   the surface condition of the second diffusion surface (166) is adapted to limit the phenomena of capillarity.   10. spray device according to any one of claims 1 to   9, characterized in that it comprises a terminal duct (184) with a flared end (186) capable of being displaced relative to the edge (132) of the diffusion surface.   11. Agricultural machine equipped with at least one spraying device according to   any one of claims 1 to 9, for the treatment of cultures, soils.