US2275691A - Apparatus for atomizing liquids - Google Patents

Description

March 10, 1942. 4 w, A SIMANwN 2,275,691

APPARATUS -FOR ATOMIZING LIQUIDS Filed Jan. 24, 1941 Patented Mn. 10, 1942 4 OFFICE APPARATUS FOR ATOMIZING LIQUIDS William A. Simanton,

burgh, Pa,

akmont, la., minor to Gulf Research a Development Company, Pittsa corporation of Delaware Application January, 1941, Serial No. 375,852 Claims. (or. 299-140) This invention relates to apparatus for atomizing liquids; and it comprises an apparatus for spraying liquids including a conical nozzle tip having near'its base a sharp-edged flange cooperating with the tipto define an annular reentrant zone downstream with respect to the- .fiange, a central passage for feeding liquid to be sprayed and lateral passages leading therefrom, the lateral passages opening on the upstream side of the sharp-edged flange, and means for supplying liquid to the central passage and for supplying a blast of air over said flange; all as more fully hereinafter set forth and as claimed.

Heretofore, considerable dimculty has been experienced in obtaining, in portable apparatus, the degree of atomization which is necessary for the most 'eflicient spraying of liquids. The most widely used spraying apparatus of the prior art,

has been of two general types. The first of these types has a relatively small orifice at the end of the spraying unit through which high pressure liquid, or air and liquid pass. The second type employs a large volume of high velocity air at low pressure and eflects atomization by impact against a stream of liquid flowing from an orifice of the type having no obstructions impeding the forward flow of the liquid. The, disadvantage of the first type is that although a fine spray isobtained, it to any great distance beyond the apparatus, unless inconveniently high pressures are employed; above, say pounds. Such pressures are difilcult to obtain in portable equipment with fractional horsepower motors. With the second type atomization is relatively poor. The stream of spray blown from the nozzle is made up 01' large droplets which do not remain suspended in the air for any great length of time.

Among the objects achieved in the herein describedinvention is the provision of a spraying apparatus capable of forming a relatively flne spray and projecting it a great distance from the nozzle.

This and other objects are achieved by the provision of a nozzle having a conical tip which is skirted by a sharp-edged flange that functions to spread out the air and liquid by the force of it is impossible to project I their impact against the flange immediately after they contact each other. The continued blast of air forces the intermingled liquid over the sharpedged flange where it is subjected to a disrupting air turbulence due to the Venturi eflect caused by expansion of the air stream as it fiows over the fiange and into the region beyond the flange. The released air envelops the atomized liquid and projects it with considerable force as a fine mist. The invention, while advantageous in all sorts of spraying systems, is especially suited for spraying liquids of relatively low viscosity typified by water and kerosene.

In the accompanying drawing I have shown more or less diagrammatically, an example of a specific embodiment of the invention as embodied in an insecticide spraying unit. In the showing,

Fig. 1 is a view in central longitudinal section of my nozzle tip fixed at the end of an inner liquid passage at a particular position relative to the outer air passage,-

Fig. 2 is a side elevation of a complete sprayer unit embodying the invention, comprising a nozzle and conduit connections thereto, spray tank and motor-fan, and

Fig. 3 is a view of the nozzle tip alone, in plan.

Referring to the drawing, reference character I indicates the motor-fan unit of the spraying apparatus, having a handle 2 attached thereto, the outlet of the motor-fan unit I being connected by a collar 3 to a conduit 4. Located in conduit 4 is a deflector or by-pass 5 for applying air pressure from the conduit to a tank 6 secured to the conduit. A handle I is provided. An opening 8 is provided in the tank for filling the container with liquid to be sprayed. Leading from the tankt is a pipe 9 which is located within the conduit 4 so as to define concentric outer and inner passages, for air and liquid respectively. The tank and blower construction rangements may be used.

The nozzle tip it is connected to pipe 9 by means of aninternally threaded sleeve portion II. An interior cavity or passage I2 is formed in the tip immediately downstream of the threaded area of the sleeve. Leading from the cavity I2 are a plurality of lateral passages II (shown as four in number) which open on the outer periphery of the nozzle tip.

Skirting the outer periphery of the nozzle tip at a point downstream with respect to the outlets of lateral passages I I is a sharp-edged flange ll, of steeper walls than the conical portion I of the tip, so as to define an annular reentrant zone Ii. feet as hereinafter described. Notches II are provided in the conical portion It to facilitate the removal of the tip by a wrench or similar tool.

In operation the sprayer unit functions as follows: Motor-fan unit I blowsair underlow pres-.-

This construction gives a Venturi efair passes through by-pass 5.into tank 6 andexerts pressure on the liquid therein to force it out through the inner liquid passage 9. The liquid flows from tube 9 into the nozzle cavity and then out through lateral passages l3. The liquid emerging from the lateral passages strikes the main air blast blown through the passage l caus-,

ing it to strike against flange I4, the impact of which spreads theliquid out. The blast of air forces the liquid to be blown over the sharpedged flange where it is subjected to a disrupting air turbulence. This turbulence is caused by the Venturi effect of the flanged edge I4 which causes a temporary rise of air pressure and a sudden drop beyond the flange in the region of "the reentrant zone IS. The released air envelops the atomized liquid and distributes it with considerable force past the conical section H5 in an outwardly diverging conical stream of mist.

' The change in diameter of the conical tip from the edge of flange l4 past the reentrant portion i5 to. the point I6 is of considerable importance as it forms an air flow pattern for-the zone of turbulence which breaks up the mist and prevents the liquid from wetting the tip. The length and shape of the conical section is also sent a substantially perpendicular surface, and at least one liquid passage in the body leading from said cavity to a point adjacent the upstream side of the flange,

2. In combination, a nozzle tip comprising a substantially conical body having a liquid-receiving cavity therein adjacent its base, an annular sharp-edged flange surrounding the conical body adjacent its base and at least one'liq uld passage in the body leading from said cavity to a point adjacent the upstream side of the flange, and an air conduit of interior diameter somewhat greater than the .base of the nozzle,

terminating in a plane spaced slightly upstream with respect to the flange.

3. In a conical nozzle tip, a sharp-edged flange adjacent the base of the conical tip and cooperating with the tip to define an annular reentrant zone downstream with respect to the flange, said flange presenting a continuous surface substantially perpendicular with respect to the base of the nozzle tip and terminating in a circular knife-like edge, a central passage for feeding liquid to be sprayed and lateral passages leadof importance inasmuch as an excessively long conical-tip will be wet by the spray due to coalescence of the liquid particles into large droplets which are blown off at the point. An excessively short conical tip will cause too coarse a spray; though the tip can be somewhat shorter than that shown. The dimensions shown are good. The nozzle tip is shown embodied in one particularly-good form of spraying apparatus;-

but it is useful in other relations. It can be embodied in any suitable material, metallic or nonmetallic.

' While I have described in detail the operation of the atomizer of my invention only in. its application to the spraying of liquids in a portable sprayer unit, the invention can be utilized in other kinds of apparatus, as in fuel oil burners and carburetors; especially where projection of a finely divided spray of low-velocity liquid is to be provided, with a low pressure source.

- What I claim is:

1. A nozzle tip comprising a substantially conbase, an annular knife-like flange surrounding the conical body adjacent its base and rising steeply from the base to said sharp edge to pre- -ical body having a cavity therein adjacent its ing therefrom, said lateral passages opening on the upstream side of the sharp-edged flange.

4..In a nozzle, a conical nozzle tip having a sharp-edged flange of approximately triangular cross-section skirting the outer periphery thereof and cooperating with the said tip to define an annular reentrant z'one downstream with respect to the flange, said flange presenting a continuous upstream surface rising steeply from the base of the nozzle tip, a central passage for feeding liquid to be sprayed and lateral passages leading therefrom, said lateral passages opening on the upstream side of the sharp-edged 'flange, and means for delivering a blast of air

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