Ultrasonic spraying device.

This invention relates to an ultrasonic spraying device comprised of a body wherein a core which generates piezo-electric vibrations, is arranged, said vibrations being conveyed to a spray nozzle which receives the liquid to be atomized.

The object of the invention is to provide a device which markedly improves the atomizing features of the sprayed liquid.

The invention has indeed for object to generate a compact bundle of microscopic moisture droplets in the form of a spray which can be moved over a longer distance and wherewith for a given vibration frequency, the moisture particle size is smaller than usual.

The concept "compact" implies that the water droplets being spread by the spraying device and conveyed by the air, which form as it were a bundle, do not fall too fast downwards by gravity when leaving the spray nozzle, but should move as long as possible in a cone shape.

A device fitted with such a spray nozzle has already been described in Belgian Patent 902,301. In a device as disclosed in said Patent, problems are encountered due to the sprayed liquid moving downwards soon after leaving the spray nozzle, in such a way that that surface area which is reached by the sprayed liquid, is relatively limited.

The invention has thereby also for object to obviate said drawbacks and to provide a spraying device which makes it possible to cause the sprayed liquid to reach with a much higher homogeneity, at a relatively long distance, a large surface area.

To obtain such a result according to the invention, against the free end of said spray nozzle, a diaphragm is mounted which is so designed as to improve the atomizing characteristics of the liquid.

Other details and features of the invention will stand out from the following description, given by way of non limitative example and with reference to the accompanying drawings, in which: <ul id="ul0001" list-style="none"><li>Figure 1 is a part lengthwise section through the spraying device according to the invention.</li><li>Figure 2 shows diagrammatically a sprayed fluid bundle in an ultrasonic spraying device which is not fitted with a diaphragm.</li><li>Figure 3 shows the same bundle in a spraying device which is provided with a diaphragm according to the invention.</li></ul>

The device as shown in figure 1 comprises a body 1 wherein the core 2 is - mounted, which comprises the required piezo-electric components to generate the desired ultrasonic vibrations. Reference 3 shows conductors which lead to connectors 4. The core 2 is joined to a so-called spray nozzle the free end 6 of which has for example, but not necessarily, an enlarged cross-section. To body 1 is linked an extension 7 which surrounds completely said spray nozzle 5.

The supply of that liquid to be atomized occurs from a supply 8 to a centre channel provided in said spraying nozzle 5, although the liquid may also flow outwardly along the spray nozzle 5.

To improve the atomizing characteristics of the sprayed liquid in a substantial way according to the invention, a diaphragm 9 is provided in contact with the enlarged part 6 from spray nozzle 5.

The presence of said diaphragm 9 which contacts the enlarged part 6 of spray nozzle 5, comprises essentially the essence of the invention.

Although the spray nozzle shown by way of example has an enlarged part 6, the invention may naturally also be applied to spray nozzles which have a completely different shape.

It has indeed been ascertained that atomizing of the liquid in a device fitted with the above-defined means for generating ultrasonic vibrations, occurs under particularly favourable conditions. Indeed by atomizing through a diaphragm engaging a spray nozzle of the above-defined type, there is generated a bundle microscopic liquid droplets, which still has a compact structure at a suitable distance from said spraying device. Such a compact structure the general appearance of which approximates a cone, is shown diagrammatically in figure 3.

When no use is made of a diaphragm according to the invention, the bundle generated by the spraying device occurs substantially according to the profile figure 2 relates to.

In figure 2 it may indeed be noticed that the sprayed liquid droplets fall downwards directly after leaving the spray nozzle. This means also that that area which is being reached by the sprayed liquid droplets is limited and lies at too small a distance from the spray nozzle.

Such drawbacks are obviated with the spraying device according to the invention, whereby a cone-shaped bundle 10 is generated, which allows to reach longer distances, to cover a larger surface area, under improved homogeinity conditions.

Use may be made for diaphragm 9, of the most varied materials. The diaphragm may indeed be comprised of fabric, but it may also be formed by a perforated material or a moisture-pervious non-woven material.

Remarkable results have been obtained with fibers which are manufactured by the Dupont de Nemours company under the trade name "KEVLAR".

A requirement lies in the diaphragm 9 engaging said spray nozzle 5. It is assumed that the vibrations being imparted to the diaphragm result in accelerating the liquid particles which flow through the diaphragm. It has also been determined that the air dynamics is changed by the use of such a diaphragm, and that a strong air displacement occurs, which contributes to the displacement over the required distance, of the liquid particles.

This explains why the bundle fluid or water droplets which appear thereby, acts as shown in figure 3, together with the accelerating of the surrounding air.

When the sprayed liquid, particularly those droplets which compose the spray, are not being accelerated enough, there occurs a profile such as shown in 11 in figure 2, with all the drawbacks connected thereto.

Those areas wherein the spraying device according to the invention may be used, are quite varied. In any domain where atomizing or spraying of a liquid is to be applied, the device according to the invention offers very large advantages, due to the possibilities of displacing the liquid droplets in spray form over a longer distance and thereby of generating a spray which is very homogeneous and is comprised of extremely finely divided liquid particles. All such properties are noticed without having to resort to an increase in the vibration frequency.

It must be understood that this invention is in no way limited to the above embodiments and that many changes may be brought thereto without departing from the scope of the invention as defined by the appended claims.