US2855244A - Sonic liquid-spraying and atomizing apparatus - Google Patents

Description

Oct. 7, 1958 L. w. CAMP 2,855,244

SONIC LIQUID-SPRAYING AND ATOMIZING APPARATUS Filed June 3, 1955 INVENTOR.

Leon W Camp BY ATTORNEY United States Patent SONIC LIQUID-SPRAYING AND ATOMIZING APPARATUS 1 Claim. (Cl. 299-1) This invention relates to apparatus for atomizingand spraying liquids and has, as a general object, prov1sion of such an apparatus that is simple and rugged and produces a very fine atomization. It may be employed for atomizing alone, as for atomizing fuels for carburetion,

or forprojecting finely atomized liquids, as in spray painting and the like.

Briefly, the invention consists of a sonic vibrator having a liquid-conducting passage therein extending to one or more apertures in a working face. When liquid is supplied through the passage and the face is vibrated at high frequency in the sonic or ultrasonic range, the liquid is projected from the face as a fine fog or mist. For spray coating of objects, as in painting, the mist is directed onto the object. For carburetion, the mist is entrained in a current of air into which it is projected.

Various specific objects and features of the invention will become apparent from the following detailed description with reference to the drawing, in which:

Fig. 1 is a plan view of one embodiment of the invention.

Fig. 2 is a vertical, longitudinal section taken in the plane IIII of Fig. 1.

Fig. 3 is a cross section taken in the plane III--III of Fig. 2.

Fig. 4 is an end view taken in the plane IV--IV of Fig. 2.

As shown in the drawing, the invention comprises a body of electromechanically responsive material adapted to be vibrated longitudinally by extension and contraction and having a face 11 at the left end, this being the working face of the device. As used herein the expression electromechanically responsive material means any material that responds to electrical excitation to change its shape or dimensions. Magnetostrictive materials such as nickel change their shape when subjected to the magnetic field ofv an electric current. Other electromechanically responsive materials such as quartz crystals and barium titanate change shape when subjected to an electric potential.

In the form shown, the body 10 consists of a magnetostriction vibrator 12 of known type having a face 13 at its left end which is firmly bonded to the right end face 14 of .an amplifying horn 15. The horn 15 is solid, except for a water-conducting passage 16 which extends from a connecting nipple 17 in the top of the horn to the left end thereof. The nipple 17 is shown connected by a flexible hose 18 to a source of liquid, which in this instance is indicated as a pump 19 and a reservoir 20.

The left end face or working face 11, previously referred to, is defined by a separate face plate 21 which is securely bonded to the left end of the horn 15. This left end 22 of the horn has an annular groove 23 therein which is connected to the passage 16 by four radial grooves 24. Except where the grooves 23 and 24 occur, the entire face 22 is flat, and fits against and is tightly bonded to the face plate 21. The latter has an annular row of discharge apertures 25 juxtaposed to and com- "ice municating with the groove 23. It will be observed, therefore, that a path for liquid flow is provided from the nipple 17 to the apertures 25 in the end face 11 As previously indicated, the magnetostriction vibrator 12 is of conventional form, having an energizing winding 27 and a polarizing permanent magnet 28 so that when the Winding 27 is energized with alternating current of a frequency to which the body 10 is mechanically tuned, powerful vibrations are induced therein. The horn 15 functions to magnify the amplitude of the vibrations existing at the end 13 of the magnetostriction vibrator, so that the working face 11 vibrates with greater amplitude than does the end 13 of the magnetostriction vibrator proper.

When the body 10 is vibrated at a frequency sufiiciently high and with sufficient energy input to produce the necessary amplitude of vibration at the face 11, liquid passing through the apertures 25 in the face is finely atomized and discharged a substantial distance away from the face, As fluid is atomized and discharged from the face 11, the supply thereto is renewed from the reservoir 20 through the pump 19 and the hose 18. It is to be understood that very little pressure is required to maintain the fluid supply, and that in some instances it is merely necessary to position the reservoir 20 slightly above the level of the body 10 to give gravity feed of liquid to the tool as it is discharged. A valve 30 may be provided to control the rate of flow.

In Figs. 1 and 2, the liquid is shown discharged from the face 11 in the form of a mist or fog 28 which is impinged on the surface of an object 29 positioned closely adjacent thereto. In this instance, the fog is precipitated onto the surface of the object 29 in a very finely divided uniform film, making the apparatus particularly suitable for spraying paint or other coatings. The apparatus is preferable in some particular applications to the conventional spray gun employing an air blast, because there is no rush of air, the minute particles of liquid constituting the fog 28 being projected forcibly from the surface 11 and carried by their own momentum to the surface 29, rather than being carried thereto in a current of air which must be deflected laterally when it impinges on the surface 29.

When the invention is to be used for the purpose of atomizing a. liquid and mixing it with a gas, such as in the carburetion of a liquid fuel with air, the projected fog or mist 28 is projected into a moving current of air which picks it up and carries it along therewith, the two being thoroughly mixed because of the fineness of the particles of the fog or mist.

Although it is usually desirable to provide a large number of apertures 25, as shown in the example illustrated in the drawing, no particular number of apertures and no particular arrangement thereof is required. However, the cross-sectional pattern of the fog projected from the face corresponds roughly to the pattern of the apertures and can be controlled to a certain extent by arranging the apertures in the desired pattern.

The over-all length of the body 10 should be one-half wave length, or a multiple of one-half wave length, at the frequency of operation. When the over-all length is one-half wave, the body vibrates with maximum motion at its opposite ends and with minimum motion in a plane intermediate the ends. If the length of the body 10 is one wave length, maximum motion occurs at the opposite ends and also at the middle, and there are two planes of minimum motion (nodal planes), each spaced one-quarter wave length from one end. The second mode of operation has the advantage that the stress is reduced at the point of joinder of the vibrator 12 to the horn 15, and it also facilitates the location of the liquid connection 2,855,244,. e p p n nipple 17 at or near a nodal point. However, these conditions are not absolutely necessary.

In order to discharge the liquid from the face 11, the maximum velocity of the face must be relatively high and is determined by the amplitude of vibration and by the frequency. In a device having a working face 11 approximately square, dimensioned to operate at 22,000 cycles per second, satisfactory results have been obtained with an electrical power input of 25 watts. Under these conditions, the face 11 imparts to the liquid a maximum forward velocity of about fifteen feet per second and has a maximum negative acceleration of about 60,000 G. This great acceleration causes the liquid film on the face 11 to shatter into extremely small droplets.

Although for the purpose of explaining the invention a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and I do not desire to be limited to the exact details shown and described.

I claim:

Apparatus for spraying a liquid comprising: a body having a face containing a liquid-discharging aperture and a liquid-conducting passage extending from said aperture through said body to a liquid supply connection thereon; means for generating in said body and transmitting to said face compressional wave energy in direction perpendicular to said face and of power and frequency high enough to vibrate said face at a velocity sufficient to eject therefrom liquid particles reaching said face through said aperture; said body comprising a rear portion remote from said face of electromechanicallyresponsive material and a front portion extending from said rear portion to said face, said liquid-conducting passage being contained within said front portion; said front portion having a vibrational node displaced from said face and said liquid supply connection being located at said node.

References Cited in the file of this patent UNITED STATES PATENTS 2,453,595 Rosenthal Nov. 9, 1948 2,512,743 Hansell June 27, 1950 2,738,173 Massa Mar. 13, 1956 FOREIGN PATENTS 826,088 Germany Jan. 7, 1952

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