Fluid sprinkling – spraying – and diffusing – With means to vibrate or jiggle discharge – By electric transducer
Patent
1994-05-26
1996-05-21
Kashnikow, Andres
Fluid sprinkling, spraying, and diffusing
With means to vibrate or jiggle discharge
By electric transducer
B05B 108
Patent
active
055181791
DESCRIPTION:
BRIEF SUMMARY
This invention relates to apparatus and methods for the production of droplets of fluid, liquids or liquid suspensions (hereinafter called `fluids` or `liquids`), by means of an electromechanical actuator (preferably an electroacoustical actuator).
It is known to produce fine droplet sprays, mists or aerosols (hereinafter called `sprays`) by the action of high frequency mechanical oscillations upon a liquid at its surface with ambient air or other gases. Prior art of possible relevance includes the following patent specifications: GB-A-2041249, US-A-3812854, US-A-4036919, DE-A-3434111, DE-A-3734905, US-A-4533082, EP-A-0432992 & EP-A-0480615, and Physical Principles of Ultrasonic Technology by Rozenberg, published in Plenum.
In some instances (e.g. DE-A-3734905 & US-A-3812854) the liquid-gas surface is several millimeters away from a source of mechanical oscillations placed within the liquid and the aerosol is created by the action of these oscillations propagated as sound waves that pass through the liquid to the liquid surface. In some such cases (e.g. US-A-3812854) the liquid-gas surface is constrained by a porous medium.
In other cases (e.g. GB-A-2041249) the liquid is in the form of a thin film on a non-porous membrane which itself is driven by a similarly remote source of mechanical oscillations.
These methods generally have low efficiency of energy utilisation in the production of the droplet spray or are of relatively high manufacturing cost.
In yet other cases (e.g. US-A-4533082) the source of mechanical oscillations is closely adjacent to a porous membrane and the excitation passes directly from the source to the porous membrane. This method improves efficiency to some degree, but the apparatus remains a relatively complex assembly and has a relatively limited range of operating conditions. For example, it requires a fluid chamber.
In still other cases (e.g. EP-A-0431992) improvements in efficiency are sought by coupling the vibrating means to a perforate member by mean of an annular member having a relatively thinner annular portion connected to the perforate membrane and a relatively thicker outer annular portion connected to the vibrating means. This member is claimed to act as an impedance transformer whereby relatively small amplitudes of acoustic vibration of the vibrating means are amplified prior to their transmission into the perforate member. This specification discloses the use of additional components (for example, a fluid chamber) and also has a relatively limited range of operation conditions.
It is known from US-A-4533082 and from EP-A-0432992 to provide dispensing apparatus comprising a housing defining a chamber receiving in use a quantity of liquid to be dispensed, the housing comprising a perforate membrane which defines a front wall of the chamber and which has a rear face contacted by liquid in use, the apparatus further comprising vibrating means connected to the housing and operable to vibrate the perforate membrane to dispense 26 droplets of liquid through the perforate membrane.
US-A-4533082, discloses a fluid droplet production apparatus with a membrane and a piezo-electric actuator that contracts and expands in order to drive the membrane.
An object of the present invention is to overcome the various problems associated with the prior art apparatus land methods and, specifically, to improve the simplicity of the device.
According to a first aspect of the present invention there is provided fluid droplet production apparatus comprising:
a membrane;
an actuator, for vibrating the membrane, the actuator comprising a composite thin-walled structure arranged to operate in a bending mode and to vibrate the membrane substantially in the direction of actuator bending; and means for supplying fluid directly to a surface of the membrane, as fluid is sprayed therefrom on vibration of the membrane.
Thus, the membrane is structured so as to influence the menisci of fluid introduced to the membrane.
Preferably, the actuator is substantially planar, but it is envisaged that thin-walled
REFERENCES:
patent: 3812854 (1974-05-01), Michaels et al.
patent: 4036919 (1977-07-01), Komendowski et al.
patent: 4533082 (1985-08-01), Maehara et al.
patent: 5152456 (1992-10-01), Ross et al.
Humberstone Victor C.
Newcombe Guy C. F.
Palmer Mathew R.
Sant Andrew J.
Kashnikow Andres
Morris Lesley D.
The Technology Partnership Limited
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