Abstract:
Such apparatuses are used for discharging active substances along with various carrier media, water often being used as a carrier medium. In order to ensure that the water perfectly nebulizes together with the active substance, the mist pipe ( 10 ) comprises at least three additional pipes ( 3  to  6 ) which partly surround each other to form annular chambers ( 31  to  33 ). Such a mist pipe ( 10 ) allows the size distribution of the drops to be kept within narrow limits even when water is used as a carrier medium. The nebulizer and the mist pipe ( 10 ) are mainly used in the health sector, in agriculture, plantations and greenhouses, for protecting supplies and for disinfection purposes on humans, in animal husbandry, and in food production.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns an apparatus for discharging sprays or mists, comprising an oscillating fire burner to which is connected a resonator, into which a supply line for the mist material opens and which projects into a first pipe of a mist pipe, as well as a mist pipe for such an apparatus. 
     Such apparatus are utilized for discharging active ingredients (preparations) with different carrier materials. The carrier material serves to discharge the entrained active ingredient, for example, insecticides, fungicides, pesticides, disinfecting agents, in mist form (aerosols). As a carrier material water is frequently used. The use of aqueous active ingredient mixtures (preparation mixtures), in the following referred to as mist material, with water as a carrier material is critical when a conventional mist pipe is used. When misting with such a mist pipe, a very broad droplet spectrum is generated with a high proportion of large droplets that are not able to float. 
     The invention has the object to design the apparatus of the aforementioned kind and the mist pipe of the aforementioned kind in such a way that a proper misting action of the water with the active ingredient is ensured. 
     SUMMARY OF THE INVENTION 
     This object is solved in connection with the apparatus of the aforementioned kind for discharging sprays and mists in accordance with the present invention in that the mist pipe comprises at least three further pipes that, with formation of annular chambers, overlap one another at least partially, and in connection the mist pipe of the aforementioned kind in accordance with the present invention in that mist pipe has at least four pipes that have in the direction of the free end increasingly greater radius and each project axially past the inner pipe, respectively. 
     The apparatus according to the invention has a mist pipe suitable for discharging aqueous mists comprising at least four pipes that are partially inserted into one another with formation of annular passages with the purpose of generating only floating droplets (aerosols) and to exclude large non-floating droplets. Should upon misting at the end of the third pipe larger droplets be formed, they fall onto the projecting parts of the fourth pipe and are caught in this way. In this way, the size distribution of the droplets can be kept within narrow limits. Therefore, the throughput (liter per hour) of the water-based mist material can be significantly increased and still an optimal misting with a good aerosol droplet spectrum can be achieved. Of course, as needed, further pipes can be provided. 
     Advantageously, the third pipe is provided with at least one suction opening for larger mist droplets contained within the annular passage. The exhaust gas/cooling air stream flowing through the mist pipe at high speed generates via the suction opening of the third pipe a vacuum in the annular passage. The larger droplets that have been caught by the fourth pipe are thereby sucked into the annular passage and pass through the suction opening into the third pipe. Here they are entrained by the exhaust gas/cooling air stream and broken apart. 
     In case of further pipes it is advantageous that each further pipe is provided with at least one suction opening for the droplets exiting from the preceding pipe. 
     Further features of the invention result from the additional claims, the description, and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in the following in more detail with the aid of an embodiment illustrated in the drawings. It is shown in: 
         FIG. 1  in axial section a mist pipe according to the invention that is placed onto a resonator and a cooling pipe of a misting apparatus; 
         FIG. 2  the mist pipe according to  FIG. 1  without the resonator in an illustration in accordance with  FIG. 1 ; 
         FIG. 3  in schematic illustration the droplet distribution upon misting with the apparatus according to the invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The mist pipe  10  illustrated in  FIGS. 1 and 2  is a high-performance mist pipe that is placed onto a resonator  2  and a cooling pipe  7 . The resonator  2  is a cylindrical pipe that forms the extension of an oscillating fire burner. Near its end facing away from the resonator  2  a supply line opens into the oscillating fire burner by means of which fuel, preferably gasoline, from a tank that is part of the misting apparatus is supplied. In the oscillating fire burner the gasoline is combusted wherein the combustion of the gasoline generates regular explosions that in the resonator or oscillation pipe  2  cause the gas column to oscillate. Into this oscillating gas stream near the forward end of the resonator pipe  2  the mist material is supplied by a supply line  9  and is broken apart into smallest particles. The supply line  9  is provided in a connecting member  8  that projects through an opening  11  in the pipe  4  and extends to the resonator  2 . It is provided with an opening  34  through which the supply line  9  projects into the resonator  2  preferably to about half the cross-sectional height. The pipe  3  rests with one end against the connecting member  8 . 
     The mist material is comprised of a mixture of an active ingredient, generally an active ingredient formulation, for example, an insecticide, a pesticide, a fungicide, or a disinfecting agent, with a carrier material that in the present example is preferably water. The mist material is contained in an active ingredient tank (not illustrated) from which it is conveyed in a known manner. From the mist pipe  10  that is configured of the oscillating fire burner, the resonator  2  and the cooling pipe  7 , the mist material then will exit, prepared as a floating aerosol mist. 
     The cooling pipe  7  surrounds the oscillating fire burner and the resonator  2  at a spacing and extends coaxially to them. By means of at least one opening at the end of the cooling pipe  7  facing away from the resonator  2  during use of the misting apparatus primary cooling air is sucked in. It is sucked in by the exhaust gas that exits at high speed from the resonator  2  as a result of the vacuum created thereby. This primary cooling air flows then in the annular space  25  between the oscillating fire burner and the resonator  2  in the direction of arrow  26  in  FIG. 1 . Through this cooling air flow the wall of the resonator  2  and of the resonator combustion chamber is cooled. The primary cooling air mixes with the exhaust gas/mist material mixture at the exit end of the resonator  2 . By this mixing action the temperature of the mist material/exhaust gas/air mixture is reduced. 
     The misting apparatus is mainly used in the health-care field for fighting malaria, dengue fever and other diseases that are transmitted by mosquitoes and for fighting flying and crawling insects etc.; in agriculture, it is used for plant protection measures, in plantations, and greenhouses as well as in storage protection for pest control in warehouses and silos and for inhibiting potato germination. Further fields of use are disinfection measures on humans, in animal husbandry, and food production. 
     The resonator  2  projects axially past the cooling pipe  7 . The mist pipe  10  has a first pipe  3  that is surrounded by a second pipe  4  of the mist pipe  10  at a spacing. The second pipe  4  projects past the first pipe  3  at both ends. With one projecting end  16  the second pipe  4  is pushed onto the cooling pipe  7 . 
     The inner first pipe  3  is secured by a spacer  12  within the second pipe  4 . The spacer  12  is advantageously star-shaped and has, for example, three arms  27  distributed about the circumference that each have at the radial inner and outer sides  28 ,  29  contact surfaces with which the arms  27  rests against the resonator  2  or against the inner side of the second pipe  4 . In this way, the pipe  3  is aligned properly relative to the resonator  2  and the pipe  4 . The pipes  2  to  4  are positioned coaxially to one another. Between the resonator  2  and the pipe  3  an annular passage  30  and between the two pipes  3  and  4  an annular passage  31  is formed. 
     A pipe  5  is attached on the pipe  4 . It is significantly shorter than the pipe  4  and is seated with an end section  19  having a reduced diameter on the pipe  4 . So that between the end section  19  and the pipe  4  in the area of the misting apparatus no air is sucked in, the end section  19  rests tightly against the exterior side of pipe  4 . This can be achieved by a seal-tight weld in a simple way in order to prevent that in operation of the mist apparatus air can be sucked in between the end section  19  and the pipe  4 . The pipe  5  surrounds the pipe  4  at a spacing so that between the two pipes  4 ,  5  an annular space  32  is formed. The pipe  5  projects axially past the pipe  4 . The annular space  32  tapers across a small axial length at the transition to the annular end section  19 . A pipe  6  is seated with an end section  29  having a reduced diameter on the pipe  5  and projects axially past the pipe  5 . The end section  20  is seated on the pipe  5 , preferably by means of a weld, so that in use of the misting apparatus no air can be sucked in between the end section  20  and the pipe  5 . Between the two pipes  5 ,  6  an annular passage  33  is formed which tapers at the transition to the annular end section  20  across a small axial length. 
     The mist pipe  10  in the described embodiment is comprised of four stages wherein the four stages are formed by the coaxially positioned pipes  3  to  6 . Depending on the use of the misting apparatus the mist pipe  10  may have additional stages that are also each formed by pipes that are embodied and attached in accordance with the pipes  5 ,  6 . The stages  3  to  6  are matched relative to one another such that an optimal discharge of the mist material is achieved. Since the inner cross-section increases from the resonator  2  toward the pipe  6 , the flow velocity v 1  to v 4  of the exhaust gas/mist material/cooling air mixture decreases accordingly. The mixture has at the exit from the resonator  2  the highest and at the exit of the pipe  6  the lowest flow velocity. 
     This stepping of the flow velocities v 1  to v 4  is matched to the length of the projecting parts of the pipes  3  to  6  and/or to the exit surface area of the annular passages  30  to  33  and/or the volume of the pipes  3  to  6 . Also, the cross-sectional surface areas and the volumes of the pipes  3  to  6  are matched relative to one another in order to achieve a large discharge quantity of the mist material with lowest possible undesirable formation of large non-floating droplets. 
       FIG. 3  shows approximately the droplet distribution in the discharged mist. With the dash-dotted line the droplets spectrum of conventional misting apparatus or mist pipes is illustrated. It is characterized in that very different droplets sizes occur in a broad droplet spectrum which is apparent by the flat curve. In particular, a high proportion of very large droplets occurs that will deposit in immediate vicinity of the apparatus; this decreases and impairs the efficiency of an application significantly. Fewer droplets and thus less active ingredient will reach the application target. 
     Entirely different conditions exist when using the described mist pipe  10 . As indicated by the solid line, the greatest portion of the droplets has a diameter in the range between approximately 10 m approximately 30 m. The proportion of larger droplets is minimal. This optimal droplet distribution is achieved with water as carrier material. This droplet spectrum is only minimally wider than the droplet spectrum that occurs upon discharge of mist material in which oils are used as a carrier material and which are operated with conventional mist pipes. 
     As a result of the described configuration of the mist pipe  10 , the throughput of the exhaust gas/mist material/cooling air mixture with water as carrier material can be significantly increased while providing an optimal droplet spectrum. 
     The numerical values described in the following are to be understood as an example and do not limit the invention to these values. 
     The projecting length of the pipes  3  to  6  past the inner pipe, respectively, is referenced in  FIGS. 1  at L 1  to L 4 . The pipe  3  projects by the length L 1  past the resonator pipe  2 . Correspondingly, the pipe  4  projects with length L 2  past the pipe  3  and the pipe  5  with length L 3  past the pipe  4 . In this connection, the following applies:
         L 1 &gt;L 2 &gt;L 3 &gt;L 4         

     The ratio L 1 :L 2  is in a range between approximately 1:0.6 to approximately 1:0.7. The length ratio L 2 :L 3  is between approximately 1:0.4 and approximately 1:0.5, while the length ratio L 3 :L 4  is between approximately 1:0.7 and approximately 1:0.8. 
     In one embodiment, the lengths are as follows:
         L 1 =63 mm   L 2 =42 mm   L 3 =20 mm   L 4 =15 mm       

     The cross-sectional surface areas of the annular passages  30  to  33  are identified in  FIG. 1  with A 0  to A 3 . The annular passage  30  has the smallest cross-sectional surface area A 0  while the neighboring annular passage  31  has the largest cross-sectional surface area A 1 . In this way, the primary cooling air that flows in direction  26  in the annular space  25  has in the annular passage  30  a higher flow velocity than in the annular passage  31 . The exhaust gas/mist material mixture exiting at high speed from the resonator  2  is mixed with the cooling air that flows also at high speed through the annular passage  30 . 
     The annular passage  32  has the cross-sectional surface area A 2  that is smaller than the cross-sectional surface area A 1  of the annular passage  31  but greater than the cross-sectional surface area A 3  of the annular passage  33 . The annular passages  32 ,  33  have the task to catch larger droplets that have formed in the pipes  4  and  5  and to return them to the exhaust gas/mist material/cooling air mixture flowing through the mist pipe  10 . For this purpose, the pipes  4  and  5  each are provided with at least one opening  23 ,  24  that opens into the annular passage  32 ,  33 , respectively. 
     In use of the misting apparatus it cannot be prevented that at the exit end of the pipes  4 ,  5  larger droplets  35  are formed that are no longer entrained by the exhaust gas/mist material/cooling air mixture. These droplets  35  drop onto the next pipe. respectively. By means of the mixture that is flowing at high speed through the pipes  4 ,  5  via the openings  23 ,  24  in the annular passages  32 ,  33  a vacuum is created. By means of it the droplets  35  are sucked into the annular passage  32 ,  33 , respectively, and are returned through the openings  23 ,  24  into the exhaust gas/mist material/cooling air stream. The droplets  35  are entrained by it and broken apart. 
     The vacuum action in the annular passages  32 ,  33  is so high that the pipes  5 ,  6  with their end sections  19 ,  20  rest seal-tightly against the pipes  4 ,  5 . In this way, no external air will reach the annular passages  32 ,  33  that would impair the vacuum action. 
     In the embodiment the cross-sectional surface area
         A 0  is approximately 20 mm 2      A 1  is approximately 30 mm 2      A 2  is approximately 27 mm 2      A 3  is approximately 22 mm 2          

     The cross-sectional surface areas are matched to one another such that, on the one hand, the exhaust gas/mist material/cooling air mixture exits at high speed from the mist pipe  10  and by doing so, on the other hand, the formation of larger droplets that are non-floating aerosols is limited to a minimum. 
     The following cross-sectional surface area ratios are optimal:
         A 0 :A 1 =approximately 1:1.3 up to approximately 1:1.6   A 1 :A 2 =approximately 1:0.7 up to approximately 1:0.9   A 2 :A 3 =approximately 1:0.7 up to approximately 1:0.8       

     Since the flow velocity v 1  at the exit of the resonator pipe  2  is very high, the projecting length L 2  of the pipe  3  can be correspondingly large. Correspondingly, the difference between the volumes of the pipes  3  to  6  can also be correspondingly large. 
     In the embodiment, the pipes  3  to  6  have the following volumes.
         pipe  3  V 0 =680 mm 3      pipe  4  V 1 =3,000 mm 3      pipe  5  V 2 =1,500 mm 3      pipe  6  V 3 =950 mm 3          

     The volumes refer to the area of the pipes  3  to  6  that project past the respective pipe. 
     The pipe  4  has the greatest volume V 1 . Based on this pipe  4  the volumes V 2 , V 3 , V 4  of the pipes  5 ,  6  decrease. In connection with the decreasing projecting length L 3 , L 4  and/or the decreasing flow velocity v 3 , v 4 , the discharge of the mist material at minimal droplet formation is optimized. 
     In the embodiment, at the free end of the pipe  3  a slant  36  is provided so that a circumferentially extending annular edge  37  is formed. It is advantageous to provide such slants also on the other pipes  4  to  6 . The annular edges form clean break-away edges for optimal droplet preparation.