description lang="EN" 
[0001] The object of the present invention is a method for producing fine salt dust in the breathing air by means of a device producing salt dust, i.e. salt dust generator - and the salt dust generator used in the present method. 

[0002] The method and the generator according to the invention are used for example in salt room therapy, wherein fine salt dust is blown by a salt dust generator into a room lined with salt. The salt dust provides the room air with negatively charged particles that, when inhaled, have infection reducing and phlegm detaching influence in the respiratory tract, thus opening the tract and easing respiration. In salt room therapy, the amount of salt that reaches the body system is so small that it does not cause additional swelling or adverse increase in blood pressure. Typically, a treatment session takes about 40 minutes at a time for an adult and about 5 - 10 minutes for a small child. 

[0003] Currently, on the occasions described above, a method is used wherein the salt generator automatically measures out the right amount of granular salt into a steel tank, wherein blades operated by a motor consequently mill the salt fine. The salt dust thus provided is thereafter conducted by air flow into the air of the salt room to be inhaled by the patient. Salt particles are known to have a therapeutic effect when their size is less than 5 micrometres. 

[0004] Another method by the prior-art technique to produce fine salt dust is to blow air thought a vessel where the lid and the bottom are made of net. The salt particles that have been put into the vessel fly in the air flow, collide with each other and break down to smaller particles. In this method, it is also possible to use obstacles inside the vessel, like for example nets to increase the amount of collisions. When the salt particles that have passed the obstacles come to the other end of the vessel, a part of them has reached a smaller size that is favourable for the health, i.e. the particles are less than 5 micrometres in size. 

[0005] The main disadvantage of the prior-art technique can be considered to be that a great proportion of the salt particles produced by the prior-art methods are larger than 5 micrometres in size, rendering them useless for purposes of the therapy. Thus, a reasonable effort will not provide an optimal result with regard to the particle size of the salt. 

[0006] The prior-art technique described above is widely employed in salt room therapy and salt mask therapy. One method of the prior-art technique and apparatus to produce fine salt dust is presented in the patent publication no: WO 2008/060173 . The apparatus according to this publication has a vessel, wherein the salt material to be made fine is put, and it also includes a filter that has been put inside the vessel between two nets. When the air is blown into the vessel through a hole in its bottom, the salt particles collide with each other and then they penetrate through the filter. A part of the salt particles that are lead to the mask are favourably less than 5 micrograms in size. It is evident that the size of the filter in this prior-art technique cannot be set so that only the particles of max 5 micrometres of size can penetrate through it because this would cause the filter to clog very soon. In this case, one must be satisfied with an end result where only a part of the particles going to the therapy are less than 5 micrometres in size. 

[0007] The present invention aims to provide such a method and apparatus used therein that disadvantages of the prior-art technique can be avoided. The characteristic features of the method according to the invention have been presented in the characterising part of claim 1 and the characteristic features of the salt dust generator have been presented in characterising part of claim 2. 

[0008] The main advantage of the invention, in relation to prior-art technique, can be deemed to be that all salt particles generated by the method according to the invention are therapeutically useful, less than 5 micrometres in size. Therefore, the therapy provided by the method is safer and can be targeted more accurately than that with prior-art technique. As an example of advantages obtained by using the method according to the invention, it can be mentioned that salt dust that is dry and fine enough also penetrates efficiently into the periphery of the respiratory tract. Also, when entering the skin pores, the salt dust absorbs moisture from the surrounding air even better than before and thus keeps the skin moisturised and elastic. 

[0009] An indisputable advantage is achieved also with a salt dust generator used with the method of the present invention because its construction and operation principle are simple. The milling of the salt particles in it is based in a simple mechanical procedure and the separation of the particles that are suitable for the therapy from the rest of the particles is based in physical event. Therefore, the apparatus according to the invention has a simple construction and it is easy to make it. This, in turn, is advantageous economically. 

[0010] The invention will be described in more detail by the attached drawings, wherein
Fig 1 shows a vertical section of the schematic view of the salt dust generator according to the invention in operational readiness,
Fig 2 shows a vessel lower part section of the schematic view of the salt dust generator according to the invention,
Fig 3 shows a schematic view of the apparatus used in the salt dust generator according to the invention.

[0011] Below, an advantageous embodiment of the invention will be described by way of an example of its structure and function, with reference to the above mentioned figures. 

[0012] The salt dust generator, in this example, is formed by a vessel 1 ( Fig 1 ) with a cylindrical shape standing in an upright position, preferably about 300 mm in height and the diameter D1 about 80 mm. Upon this vessel 1, there is a flow space 2 which in this example is essentially of the shape of an egg, the greatest diameter being about 250 mm. The bottom 3 of the vessel 1 is partially net. The net 4 is in the middle of the bottom covering about a half of the surface A1 of the bottom 3 diameter D1. The material is solid in the peripheries of the bottom forming a ring like area 5. A layer of about 20 mm of granular salt 6 is placed upon the bottom 3 ( Fig 2 ). The salt particles are bigger than the mesh size of the middle part net 4 of the bottom 3 so that they remain inside the vessel 1. Air 7a is blown through the net 4 of the bottom using a fan and thus the salt particles start moving. While moving, the salt particles collide with each other and with the collision obstacles that have been installed inside the vessel 1 in its lower part, i.e. against nets 8, and thus the size of the particles decreases and the amount of them increases. As the peripheral area 5 of the bottom 3 is solid the air flow 7a goes only through the net in the middle leaving the peripheral area 10a outside of the air flow. When the air flow 7a is regulated suitable, the biggest of the flying salt particles 9a fall back to the bottom when they come to this area of weaker air flow 10a. Due to the pressure difference between the stronger and weaker air flow, these particles get sucked back to the stronger air flow 7a and they rise again and collide again with each other and the nets 8. When the salt particles that have been ground and broken smaller and the salt particles that are bigger and capable of going up 9b in the air flow 7a in the middle of the vessel 1, when they get to the flow space 2 upon the vessel 1, the cross-sectional area gets bigger when going to the direction of the air flow, that is upwards, and the speed of the air flow 7b degreases and it is no more capable of keeping the heaviest salt particles flying, they start falling downwards. A part of the middle size salt particles that are not yet suitable for the salt therapy continue their way upwards and they collide with the plate 11 in the upper part of the flow space 2 because their weight is too much for being able to change the direction of flow according to the air flow 7c and thus pass the plate 11 through the openings 12 in its peripheral area. The total area of these openings 12 is favourably smaller than the area A3 corresponding the diameter D3 in the horizontal part 15 of the tube 13 that will be presented later in more detail. The salt particles 9c that are small enough in this phase of the process change direction with the air flow 7c and escape the flow space 2 through the openings 12. They go further to the tube 13 and the cross-sectional area of the horizontal part 15 is greater than the total area of the openings 12 and the cross-sectional area of the vertical part of the tube 13. Due to the difference of the before mentioned areas, the speed of the air flow 7d decreases when coming to the horizontal part 15 of the tube 13 and its power is not sufficient to carry further in the tube those salt particles 9c that are in size unfavourable for the therapy, over 5 micrometres. These salt particles 9d fall to the bottom 14 of horizontal part 15 of the tube 13. When the circulation of the salt particles in the vessel 1 down part peripheral area 10a has lasted sufficiently long time and the amount of collisions of the salt particles is sufficient, all the salt particles have become so light that they can move to the flow space 2 with the air flow 7a. When the salt particles 9e that have come to the flow space 2 but are not yet capable of changing direction with the air flow 7c, have collided a sufficiently long time with the plate 11 in the flow free space 10b they become capable of this change of direction and they escape from the flow space 2 through the openings 12. The salt dust 9f that flies in the air flow 7d is directed to the therapy device W, like salt mask, salt tent or salt room. The grain size of this salt dust 9f is almost completely less than 5 micrometres. 

[0013] The vessel 1, the flow space 2 and the shape of the tube 13 of the salt dust generator according to the invention can also be something else than what is described in the above mentioned example. These features can be selected in respective cases according to the prevailing situation. The vertical part of the tube 13 can be made of a flexible material in which case the mutual position of the therapy device W, like a salt mask, and the salt dust generator can vary in certain limits. It is essential to arrange the velocities of the air flows in the different parts of the apparatus and the mutual speed differences favourable so that salt particles colliding with each other get fine and the capacity of the air to carry particles causes separation of particles with the end result that only the particles that are almost all less than 5 micrometers come to the therapy. 

[0014] Likewise the amount of salt that is used can vary and be dependent on the before mentioned capabilities of the salt dust generator. The size of the salt grains that are used does not limit the usage range of the method or the salt dust generator according to the invention, but on the contrary, the method and the apparatus can be set to operate always according to the salt grain size in use. 

[0015] The salt particles 9d that land on the bottom 14 of the horizontal part 15 of the tube 13 are removed from the tube sufficiently often during maintenance shutdown periods. The bottom 14 of the tube 13 can be formed so that these salt particles 9d gather in certain places, like for instance into a hollow that has been made to the bottom 14 of the tube 13 for these particles. The removal of the salt particles 9d can be made for instance by disconnecting the salt dust generator from the therapy device W. 

[0016] The relation of the solid periphery area 5 with the bottom netlike area 4 of the vessel 1 of the salt dust generator according to the invention can be any suitable relation. 

[0017] The salt dust generator according to the invention can also be made without the inside net 8 of the vessel 1 and in that case the salt dust 9f is obtained by the collision of the salt particles with each other and by the collision of the salt particles with the plate 11 of the vessel 1. 

[0018] The parts of the salt dust generator according to the invention can also be positioned differently than in the above example. Any position of the vessel 1, flow space 2 and pipe 13 can be considered if they are favourable for the production of the salt dust 9f within the frames of the idea of the invention as stated in the claims. 

[0019] The salt dust generator according to the invention can be made of any material that is suitable for its purpose. One favourable material for the vessel 1, flow space 2 and the horizontal part 15 of the pipe 13 is glass and then it would be easy to see the formation of the salt dust 9f. 

[0020] It must be noted that although this explication pertains to a certain type of favourable application of the invention, it is not the intention to limit in any way the use of the invention only to this type of example but many variations are possible within the inventive idea of the invention as stated in the claims. 

