US2926855A - Atomizing and spraying apparatus - Google Patents

Description

March 1, 1960 w. DURR ET AL AToMIzING AND SPRAY-ING APPARATUS 3 Sheets-Sheet 2 Filed April 8, 1952 @l QW l maui/Walz @www 7% ATTORNEYS March 1, 1960 w. LDURR` ET AL AToMIzING AND SPRAYING APPARATUS Filed April a, 1952 3 Sheets-Sheet 3 ATTO RNEYS INM,

United States Patent() ATOMIZING AND SPRAYING APPARATUS Walter Diirr, Uberlingen am Bodensee, Germany, Heinrich H. Geffcken, Appenzell, Switzerland, and Ludwig R. Huber, Franz A. Haag, and Bernhard B. Strittmatter, Uberlingen am Bodensee, Germany, assignors, by mesne assignments, to Swingfire (Bahamas) Limited, Nassau, Bahamas, a corporation of the Bahamas Application April 8, 1952, Serial No. 281,246 Claims priority, application Germany April 13, 1951 11 Claims. (Cl. 239-129) This invention relates to apparatus for atomizing and spraying liquids and more particularly concerns apparatus of this nature utilizing for this purpose the kinetic energy and heat of the pulsating exhaust gases of an internal combustion device. The liquids atomized and sprayed may be liquids which are beneficial to, protective of or destructive of plant life, such as insecticides, plant hormones and weed killers, although the apparatus is not limited to the use of liquids of any specific nature, which are hereinafter collectively called spraying materials.

An object of the invention is the production of atomizing and spraying apparatus` embodying an acoustic jet resonator comprising generally a chamber with a resonance tube connected to it, which chamber and tube are both excited at their natural frequency and heated by the pulsating flow of exhaust gases from the internal combustion device, while the spraying material is introduced into the resonance tube through a nozzle projecting into the tube near its mouth. `A vacuum is periodically. produced in the resonance tube as an incident of the standing wave of pressure pulsations therein, and this vacuum periodically draws the spraying material from the nozzle. In the resonance tube, the spraying material is heated and broken up into fine droplets or atomized, and the mist or spray thus produced is subsequently expelled from the tube during the pressure phases of the standing wave of pulsations which follow the vacuum phases.

Without further provision, the mechanical atomizing or breaking up of the spraying material might be impaired in that particles or droplets of this material would deposit on the interior wall of the resonance tube and form a continuous lm of liquid thereon. Such impairment is avoided in accordance with one aspect of the invention by providing sharp ridges or edges extending approximately perpendicular to the path of movement of oscillating gases in the resonance tube. Such ridges or edges may be formed by cutting V-shaped threads of small pitch in the interior wall of the tube.

it is important that many spraying materials, and in particular most plant protective agents, shall not be heated to such a temperature that chemical decomposition thereof takes place. When a jet of hot combustion gas is passed through a tube, considerable variations in gas temperature may occur at different points in the crosssection of the tube, due to cooling and retarding of the gas `adjacent the tube walls. The periodic reversal `in direction of gas flow, which is characteristic of the acoustic jet resonator used pursuant to the present invention, produces gas turbulence which materially reduces such temperature variations. In accordance with another feature o-f the invention, it is possible to obtain substantially uniform temperature across the resonance tube by subdividing the tube longitudinally by transverse partitions of heat conductive material, the surfaces of which are preferably provided with the sharp ridges or edges referred to above.

The effectiveness of many spraying materials is deterof the resonator to which its exhaust is connected.

2,926,855 Patented Mar. 1, 1960 ice mined by the median size of the droplets sprayed. Thus, larger droplets deposit more rapidly and are particularly suited, for example, to the treatment of plants in garden beds Vand fields with plant protective agents, while small droplet sprays that are readily carried by air currents are better suited to the spraying of high trees. It has been discovered, in accordance with a further aspect of the invention, that the median size of the droplets produced is largely, dependent upon the position of the spray material nozzle in the resonance tube, and can be varied by changing the position of this nozzle. A further object of the invention is the provision, in atomizing and spraying apparatus ofthe type described, of means for adjustably moving the mouth of the spray material nozzle within the resonance tube.

Some spraying materials yare available not only as liquid but at least in part in solid, readily meltable form. Such solid materials must be melted before spraying. This requires large amounts of heat for initial melting and lesser amounts of heat for thereafter maintaining the material in the molten state. A further object of the invention is the provision of atomizing and spraying apparatus of the type described, in which hot gas from the combustion chamber or tube of the acoustic jet resonator is supplied to atank containing the spraying material. By suitably adjusting the How of this hot gas, the spraying material may be initially rapidly heated to melt the solid material and thereafter supplied with lesser amounts of heat sucient to maintain the material molten.

The pulsating gases which heat the resonator and set up vibrations therein may be produced in different ways. It is possible to use for this purpose the exhaust gases from a rapidly operating internal combustion engine whose speed o-f operation is so adjusted that its exhaust frequency Vcorresponds to the natural acoustic frequency In this case, the driving power of the engine is preferably used for imparting additional acceleration to the spray that is formed, thereby increasing its range. It is, therefore, another object of the invention to pro-vide, in atomizing and spraying apparatus of the type described, 'a resonator which is energized by the pulsating exhaust gases of an internal combustion engine of the piston type, which simultaneously drives a compressor that feeds air to an annular nozzle located around the mouth of the resonance tube.

A device of considerably less Weight is produced by energizing the resonator by means of exhaust gas from the pulsating internal combustion that takes place in a so-called resonant pulse jet engine. Therefore, another object of the invention is the production of atomizing and spraying apparatus of the type described, in which the resonator is energized by the exhaust gas of a resonant pulse jet engine. Under certain circumstances, the resonator itself may be used to determine the frequency of the resonant pulse jet engine. In order to avoid overheating of certain spraying materials, care is taken that the plug of gas brought to combustion in the individual thrusts of the successive explosions is maintained considerably smaller than the volume of the chamber of the resonator. Thus, in accordance with this aspect of the invention, the spraying material nozzle opens into the resonance tube of a resonator having a chamber into which projects a combustion tube of considerably smaller volume than that of the chamber. A combustion mixture is detonated in 4the combustion tube periodically at the natural frequency of the resonator.

The modification of the invention last described above provides a readily portable and highly effective atomizing spraying device. In order to facilitate operation of this device, it is preferred that both the supply of the spraying material to its nozzle and the supply of fuel to the fue] nozzle of the combustion tube be independent of the position of the device. lin accordance with one aspect of the invention, this is readily accomplished by employing airtight tanks located beneath the respective nozzles and applying superatrnospheric pressure to the tanks to force their liquid content to the nozzles. The head spaces or these tanks are preferably connected to the resonator through pipes provided with throttle valves, which retard the ow from the tank to the resonator. When the resonator is energized,` the pressure peaks ot its pulses are transferred` to the head spaces of the two tanks, producing therein a superatmospheric pressure, which forces the liquids from the tanks to the respective nozzles. With this arrangement, liquid is fed to the nozzles only when the resonator is in operation. When operation of the resonator is stopped, the superatrnospheric pressure leaks off through the throttle valves, so that the liquids in the pipes leading to the nozzles flow back to the tanks.

ln describing the invention in detail, reference will be made to the accompanying drawings in which certain embodiments thereof have been illustrated.

In the drawings:

Fig. l is a diagrammatic and simplified representation of a resonator which is energized by means of a piston pump;

Fig. 2 is a graphic diagram of the movement of a particle of gas in the resonance tube of the device of Fig. 1;

Fig. 3 is an elevation, partly in section, of atomizing and spraying apparatus having a resonator that is energized by the exhaust gas of a small piston type internal combustion engine;

Fig.v 4 is a sectional elevation of a part of the resonance tube of the apparatus of Fig. 3 showing the details of an adjustable spraying material nozzle;

Fig. 5 is a sectional elevation, similar to Fig. 4, showing a modified embodiment et the resonance tube;

Fig. 6 is a sectional view taken along the line 6--6 of Fig. 5;

Fig 7 is an elevation, partly in section, of atomizing and spraying apparatus embodying the invention and having a resonator that is energized by the periodic detonations of a resonance pulse jet engine;

Fig. 8 is an enlarged View, partly in section, showing in the fuel tank and fuel feed apparatus of the embodiment shown in Fig. 7;

Fig. 9 is a sectional elevation illustrating a modified resonant tube jacket construction; and

Fig. l is a sectional elevation showing a` modied form of spraying material nozzle.

The acoustic resonator diagrammatically represented in Fig. l consists of a chamber 1 and a resonance tube 2 connected thereto. The chamber 1 is also connected to the cylinder 3 of a small, rapidly operating piston pump, which draws in air through cylinder wall openings 4 and forces this air into the resonator ll, 2 by means of a piston 5. lf the resonator is so dirnensioned that its natural frequency is 50 cycles per second, for example, and it is energized or excited at this natural frequency, it produces a standing wave of pulsations of high amplitude as soon as the number of complete oscillations of the piston reaches the value of 3,80 per minute, which equals 50 per second. At the same time, the gas plug l located in the resonance tube 5 vibrates in a standing wave in the direction ofthe double arrow A. Referring to Fig. 2, the median current U produced by the piston pump 3-5 has superimposed on it a vibration of amplitude B, and the movement of the individual gas particles of the plug P is shown by the Curve C of Fig. 2. In Fig. 2, the abscissa t indicates the time and the ordinate s indicates the path of travel of a gas particle in the plug i?. When the speed amplitude B exceeds the median speed of flow of gas, there is temporfry reversal of movement of the particle. ln other words, the gas plug P is sucked back at least in part temporarily in the direction ofthe chamber 1. Now, it' a nozzle 6, towhich the spraying material is supplied, is projected into the resonance tube 2 close to its mouth, the spraying material is sucked into the resonance tube in the direction of the chamber 1, and is thereafter expelled through the mouth ofV the resonance tube. lt has been found that in this operation, the liquid is broken up into extremely iine droplets and is, therefore, very eiectively atomized.

The device shown in 3 makes use of the operating principles described above in connection with Figs. i and 2. The exhaust of the small piston type internal combustion engine, such as the two-cycle gasoline engine t9, discharges into an acoustic resonator formed by the chamber 11 and the resonance tube l2. The resonator comprising this chamber and tube is by its size tuned to a deiinite natural frequency. lf this frequency is say S) cycles per second, the resonator will be excited at its natural frequency, it the engine l@ runs at 480() rpm.

The engine 10 drives a rotary compressor or blower 13 whose exhaust pipe 14 is disposed concentrically around the resonance tube 12 and, with the mouth of the resonance tube, forms an annular nozzle 14a, from which the compressed air supplied by the compressor 13 is ejected at a high speed. In this manner, a ring-shaped jet of compressed air is formed, which carries the jet of atomized spray material supplied by the resonance tube 12 for a considerable distance, thereby making it possible to spray the material to the tops of high trees, for example.

The air exhaust pipe 14 carries below it a tank 15 for the spraying material, and this tank is connected to the nozzle 16 by a pipe 17 provided with a valve 18. A lling spout 15a is provided on the tank 1S. Another pipe 20, connected to the resonance tube 12 and equipped with a Valve 19, passes through the tan-k 15' and serves to conduct heat to the spraying material. A pipe 21 connects the exhaust pipe 14 of the compressor 13 with the, head space of the otherwise tightly closed spraying material tank 15. VA handle 22. is provided for carrying the device.

In operation, the engine 10 is started in the usual manner (the fuel supply means and ignition system ofthe engine are not shown, as the construction of these devices is well known). As soon as the engine has reached operating speed, here assumed to be 4800 r.p.m., there is formed in the resonator 11-12 a standing vibratory wave of high amplitude, which draws from the nozzle 16, the spraying material which is raised to the nozzle by that part of the pressure of the compressor 13 that is transmitted by the pipe 21. The vibratory wave breaks up or atomizes the spraying material into very line droplets and blows the thus produced spray out of the mouth of the resonator tube 12. The spray jet thus formed is kept together and carried along for a considerable` distance by the annular sleeve of compressed air ejected from the nozzle 14a.

As shown in Fig. 4, a V-shaped narrow thread 23 is preferably cut in the inner wall of the resonance tube 12 to form a plurality of interrupting ridges or edges for those liquid particles which may tend to deposit on this wall. Consequently, no continuous tilmof liquid is formed on this wall, and all of the spraying material is ejected from the tube 12 in atomized. form.

The spraying nozzle 16 shown in Fig. 4, and at 42 in Figs. 7 and 9, consists of a tube having an obliquely cut endjwhich may be adjustably turned about the tube axis and moved axially transversely of the axis ofthe resonance tube 12. This adjustment permits variation of the size of the droplets produced. The tube 16 moves through a sealed ring-shaped recess 24 with which it communicates through lateral tube openingsV 16a and into Whichthespraying material flows from the pipe 17.

In the modified embodiment shown in Figs. 5 and 6, the resonance tube 12a is subdivided by two crossed Vlongitudinally extending walls 25 and 26. These walls are preferably made of copper or other heat conductive material and produce an approximately uniform distribution of heat throughout the cross-section of the resonance tube 12a. The walls 25 and 26 are interrupted adjacent the spraying nozzle 16. With this arrangement, the spraying material is uniformly distributed into the four parallel paths defined by the walls 25 and 26. In order to prevent the formation of continuous liquid films on the surfaces of the Walls and 26, these surfaces are corrugated to provide a plurality of interrupting ridges or edges 25a, as shown in Fig. 5. `These corrugations may take the form of the endless circular grooves and ridges shown in Fig. 5 or may comprise the ordinary spiral threads illustrated in Figs. 7, 9 and l0, the effect being the same in each case.

Instead of subdividing the resonance tube 12a by the partitions 25' and 26, this resonance tube may be coinposed of a bundle of parallel tubes. When this is done, an internal thread, similar to the thread 23, is preferably cut in each of these tubes.

In the atomizing and spraying apparatus disclosed in Fig. 7, the resonator, comprisin-g the chamber 31 andthe resonance tube 32, is excited to resonate in a particularly simple manner, that is, Without any mechanically moving parts, by a resonance jet tube 33, with an enlarged front end chamber 37 in which a combustion mixture is periodically detonated. The frequency with which these detonations occur is in the disclosed embodiment determined automatically by the resonator 31, 32, which together form a Helmholtz resonator having a resonant frequency fixed by their dimensions because the latter has a considerably lower damping than does the tube 33. The combustion apparatus is similar to that disclosed in the copending application of Walter Drr et al., Serial No. 166,611, filed June 7, 1950, now Patent No. 2,644,512, and entitled, Burner Device Having Heat- Exchanging and GasFlow Control Means for Maintaining Pyrophoric Ignition Therein.

The tube 33 is provided with an air inlet check valve 34 of a construction which will be apparent from the drawing. As a source of ignition, the tube 33 is provided with an ignition plug 35 having a glow coil 36 located in the enlarged end chamber 37 of the tube 33. The supply of fuel (gasoline, benzene, or the like), is carried in the tank 38 and is introduced into the tube 33 through a nozzle 39 in a manner hereinafter described. The tank 3S has a filler spout 3S provided with a tight cap.

The spraying material is contained in a tank 40 and is fed to the spraying material nozzle 42 through a pipe 41. The spraying material nozzle 42 is installed in the resonance tube 32 in the same manner as the spraying nozzle 16 is installed in the resonance tube 12, as shown in Figs. 3, 4 and 5 and described above. The tank 40 is air tight when the cap is applied to its filler spout 40. The head space of the tank 40 communicates with the tube 32 of the resonator through a pipe 43. In this pipe 43, there is provided a check throttle 44, which may, for example, consist of a check valve with a bypass 44 around it, or mayV comprise any known how controlling device, which has a lower iiow resistance in the direction from the tube 32 to the tank 40 than in the opposite direction. A similar pipe 45 containing a similar check throttle 46 leads from the tube 32 to the head space of the fuel tank 38. A pipe 47 leads from the chamber 31 to a heating coil 49 located Within and which heats the tank 40 containing the spraying material. An adjustable throttling valve 48 is provided in the pipe 47. The temperature of the spraying liquid contained in the tank 40 is indicated by a thermometer 50.

The resonator 31, 32 is enclosed Within a jacket tube 51, which extends beyond the mouth of the resonance tube 32 for a distance of at least about 4", and forms with the tube mouth an injector 53. This injector draws air through the ring-shaped air jacket between the tube 51 and the tube 32 and chamber 31, and this air cools 6 both the chamber 31 and the resonance tube 32. The air drawn'through this jacket is thereby heated to a relatively high temperature which may be of the order of CL The jacket tube 51 also protects the carrying handle 54 from annoying heat radiation.

The handle 54 forms the cylinder of 4a small hand pump, the piston of which is operated by a handle 55. This pump serves as a means for starting combustion in the tube 33.

In order to start the device, the ignition plug 35 is first connected with a suitable source of electric current for an interval sufficient to heat the air in the chamber 37, usually about 1 to 2 minutes. Thereupon, by means of the hand pump 54, 55, air is forced into the tube 33 through the pipe 56.` This produces superatmospheric air pressure in the chamber 31, which, through the pipe 45 and the check throtle 46 applies pressure to the fuel tank 38 and lifts fuel to thernozzle 39 through the pipe 61. When the fuel reaches the nozzle 39, the next pump thrust forceably carries the fuel into the tube 33 by means of the flow of air through the nozzle, and the fuel, thus introduced forms with the air a combustible mixture which is ignited by the glow coil 36. The` detonation thus produced energizes the resonator 31, 32 to acoustic vibrations which periodically produce a vacuum in the chamber 31. This periodic vacuum is transferred to the check valve `34 and the fuel nozzle39 through the tube 33. Under the inuence of this vacuum, the tube 33 is again charged with a combustible mixture of fuel and air which then ignites `at the glow coil 36. These intake and detonation cycles are repeated periodically, thereby producing in the tube 33 rythmic detonations in step with the natural frequency of the resonator 31, 32, and the amplitude of the pressure vibrations rises to high values (about 0.5 to 0.8 atmosphere). The glow coil 36 is kept glowing by heat from the periodic detonations, so that it is not necessary to continue electric heating of this coil .after the device has been started. The detonations follow each other with acoustic frequency until the contents of the fuel tank 3S are exhausted or until the check valve 34 is closed by hand. t In order to heat up the tank 40 containingthespraying material, the valve 48 is first opened. This causes part of the hot gases periodically expelled from the tube 33 to flow through the heating coil 49. As soon as the thermometer 50 indicates the desired temperature, thel valve 48 is throttled, and then the valve 41a is opened, so that the liquid spraying material may ow to the spraying material nozzle 42. The4 spraying material is then under the superatmosphericV pressure built up in the head space of the tank 40 by gas flowing through the check throttle 44. The spraying material entering the resonance tube 32 from the nozzle 42 is atomized within the tube 32 in the manner described above in connection with the modification shown in Fig. 3. The atomized spray is ejected from the mouth of the resonance tube 32 and is held together and carried along by a surrounding jet of air from the space between the jacket tube 51 and the resonance tube 32.

The use of the jacket tube 51, which extends beyond the mouth -of the resonance tube 32, provides the advantage that a plug of preheated air is -always located in front of the mouth of the resonance tube 32, whereby there is drawn into the resonance tube 32 during the vacuum phase of each cycle, hot air instead of cold air. This action also renders more uniform the temperature conditions to which the spraying material is subjected during its introduction and atomization in the resonance tube 32. It is, of course, preferred to provide interrupting ridges or edges on the inner wall of the resonance tube 32 by cutting V-shaped threads 32 therein in order to prevent deposit of a film of liquid spraying material on the tube-wall. It may also be desirable to provide heat conducting partitions within the tube 32, similar tey escasas 7 'the partitions described above in connection with the tube 12 of the modification of Fig. 3.

The fuel nozzle 39 shown in detail in Fig. 8 consists of a venturi tube with an annular recess 60 around its throat, from which radial' holes Iopen into the throat of the venturi. A fuel pipe 61, connected to the bottom of the fuel tank 38 through a ow regulating device, is conected to the annular recess 60. 'ihe venturi tube 39 connects the tube 33 with a condensation chamber 63, which is formed in the upper part of the fuel tank 38 and is connected to the fuel' carrying part of that tank through a tube 64. When the described resonant combustion takes place in the tube 33, the air or gas in the tube 33 passes through the venturi alternately in o-pposite directions, thereby entraining fuel from the annular recess 66. When thereis superatmospheric pressure in the tube 33, due to a ldetonation phase of the operating cycle,V fuel isv carried into the condensation space 63 where it is condensedl and returns to the lower part of the tank 38 through the tube 64. When a vacuum exists in the tube 33 during an intake phase of the cycle, the fuel is drawn into the tube 33 where it forms afresh fuel mixture with air drawn in through the check valve 34. The advantage of this fuel feed arrangement is that the fuel column is never forced back into the fuel supply pipe 61, and accordingly fuel is always present in this pipe and in. the annular recess 60 so that fuel is drawn into the tube 33 immediately and withoutl delay during the intake phase of the cycle.

in some cases, it is necessary or desirable to provide a second jacket tube surrounding the first jacket tube of the above-described embodiments, so that operators will not be injured and combustible materials will not be ignited by accidental contact with the apparatus. Fig. 9 illustrates the modifications to the form shown in Figs. 7 and 8 which will provide such jacket construction. In Fig. 9, the resonator comprising the chamber 75 and resonance tube 76 are surrounded asv before by a jackettube 77, which in turn is surrounded by a second or outer jacket tube 66 spaced from and held adjacent the tube 77 and chamber 75 by spacer 67 formed of heat insulatingv material. The mouth of the outer jacket tube 66 is extended beyond the mouth of the inner jacket tube 77 and the extension is provided with a reduced throat 68 to form with the inner jacket tube mouth an injector, which draws cooling air through the concentric space between the inner jacket tube 77 and the outer jacket tube 66. This arrangement not only protects operators against burns, but prevents the ignition of combustible materials, such as straw or dust, which may contact the outer surface of the apparatus during use.

A modified form of nozzle which may be substituted for the nozzle 16 in each of the abovedescribed modifications, for introducing the spraying material liquid into the resonance tube of the apparatus is illustrated in Fig. l0. As there shown, an annular recess 7G located directly in the wall of the resonance tube 7i adjacent its mouth opens into the interior of the rsonance tubethrough through slots 72 extending around the interior of the resonance tube, as shown. The spraying material liquid supply pipe 73 is connected to the recess 70, and spray liquid is drawn from the recess through the slots 72 during the vacuum phase of the operating cycle in the manner explained above in connection with the nozzle construction illustrated in Figs. 4 and 5.

Although the invention has been described above by reference to only a limited number of specific embodiments, it is to be understood that other means may be selected to energize the resonator and thereby obtain the above-described and hereafter claimed improvement in atomizing and spraying apparatus.

We claim:

l. Apparatus for atomizing and spraying liquids in which the liquid to-be" atomized is introduced into the pulsatingfjet. of` exhaust gassfrom t an internal i combustion $5 device comprising a resonator including a chamber and a resonance tube connected thereto and having a mouth at the end thereof remote from the chamber, an internal combustion device connected to deliver to such resonator chamber combustion gases pulsating at the natural frequency of said resonator, a nozzle opening into the interior of said resonance tube adjacent its mouth, and means for delivering the iiquid to be atomized to said nozzle, said resonance tube having ridges on the interior to deter continuous liquid film formation on said interior.

2. Apparatus for atomizing and spraying liquids as set forth in claim l in which said ridges extend substantially at right angles to the direction of movement of gas in such tube.

Apparatus for atomizing and spraying liquids as set forth in claim l in which said ridges are in the form of a thread cut in the interior of the resonance tube.

Apparatus for atomizing and spraying liquids in which the liquid to be atomized is introduced into the pulsating jet of exhaust gas from an internal combustion device comprising a resonator including a chamber and a resonance tube connected thereto and having a mouth at ti e end thereof remote from the chamber, an internal combustion device connected to deliver to such resonator chamber combustion gases pulsating at the natural fre'- quency of said resonator, a nozzie opening into the interior of said resonance tubc adjacent its mouth, and ns for delivering the iiquid to be atomized to said nozzle, said resonance tube having iongitudinally extending partitions subdividing the tube into a plurality of passages.

5. Apparatus for atomizing and spraying liquids as set forth in claim 4 provided with ridges on the interior of the resonance tube and on the partitions which extend substantially at right angles to the direction of movement of gas in the resonance tube.

6. In a pulse jet arrangement to be used with an apparatus for atomizing and spraying liquids or the like, in combination, a resonator including a resonator chamber and an elongated resonance tube communicating with and extending from said resonator chamber; an elongated resonance jet tube connected with and extending fluid-tightly into said resonator chamber, said resonance jet tube having in said resonator chamber at an end of said resonance jet tube a combustion chamber communicating with the interior of said resonator chamber and in which a combustion mixture is periodically detonated, said combustion chamber being formed by a tubular end portion of said jet tube which is a continuation of the remainder of the jet tube, which has an inlet end through which iiuid ows from said remainder of said jet tube into said combustion chamber, and which has a discharge end distant from said inlet end providing communication between said jet tube and said Vresonator chamber so that a fresh combustible mixture entering said combustion chamber through said inlet end thereof will displace the gases of the previous combustion out of said combustion chamber through said discharge end thereof; and means connected to and communicating with said resonance jet tube at the exterior of said resonator chamber for supplying a fuel-air mixture to the interior of said resonance jet tube to be detonated in said combustion chamber thereof, whereby fresh fuel-air mixture which moves into said combustion chamber displaces combustion gases of a previous detonation out of said combustion chamber into said resonator chamber so that the mixture detonated in said combustion chamber is substantially free of com* bustion gases from a previous detonation.

7. in a pulse jet arrangement as recited in claim 6, said resonance jet tube having in said resonator chamber a tubular end portion of a larger size than the remainder of said resonance jet tube and forming said combustion chamber.

8. Apparatus" for atomizing and spraying liquids or the like, comprising, in combination, a tank for the `liquid which is to be atomized and sprayed; pulse jet `from said tank to the interior of said resonance tube to be atomized in the latter and sprayed therefrom; and an elongated heating tube connected to and communicating with said resonator chamber and having a portion which extends through and terminates in an open end located beyond said tank so that some of the hot gases in said resonator chamber will be conveyed through said heating tube to heat liquid in said tank before the liquid is conveyed by said conduit means to said resonance tube.

9. Apparatus for atomizing and spraying liquids or the like comprising, in combination, a tank for the liquid which is to be atomized and sprayed; pulse jet means including a resonatorchamber, an elongated resonance tube communicating with and extending from said resonance chamber, a resonance `jet tube connected with and extending fluid-tightly into said resonator chamber and having in the latter an end portion communicating with said resonator chamber and forming a combustion chamber in which a combustion mixture is periodically detonated, said combustion chamber being formed by a tubular end portion of said jet tube which is a continuation of the remainder of the jet tube, which has an inlet end through which uid flows from said remainder of said jet tube into said combustion chamber, and which has a discharge end distant from said inlet end providing communication between said jet tube and said resonator chamber so that a fresh combustible mixture entering saidcombustion chamber through said inlet end thereof will displace the gases of the previons combustion out of said combustion chamber through said discharge end thereof, and means connected to and communicating with said resonance jet tube for supplying a fuel-air mixture thereto; and conduit means extending from said tank to said resonance tube for conveying liquid from said tank to the interior of said resonance tube to be atomized therein and sprayed therefrom.

10. Apparatus as recited in claim 8 and wherein said pulse jet means includes in addition to said resonator chamber and elongated resonance tube an elongated resonance jet tube connected with and extending fluidtightly into said resonator chamber, said jet tube having in said resonator chamber at an end of said jet tube a combustion chamber communicating with the interior of said resonator chamber and in which a combustion mixture is periodically detonated, said combustion chamber being formed by a tubular end portion of said jet 10 tube which is a continuation of the remainder of the jet tube, which has an inlet end through which fluid ows from said remainder of said jet tube into said combustion chamber, and which has a discharge end distant from said inlet end providing communication between said jet tube and said resonator chamber so that a fresh combustible mixture entering said combustion chamber through said inlet end thereof will displace the gases of the previous combustion out of said combustion chamber through said dscharge'end thereof, and means connected to and communicating with said jet tube at the exterior of said resonator chamber for supplying a fuelair mixture to the interior of said jet tube to be detonated in said combustion chamber thereof, whereby fresh fuel-air mixture which moves into said combustion chamber displaces combustion gases of a previous detonation out of said combustion chamber into said resonator chamber so that the mixture detonated in said combustion chamber is substantially free of combustion gases from a previous detonation.

11. In a pulse jet arrangement as recited in claim 6, said inlet and discharge ends of said combustion chamber being coaxial.

References Cited in the tile of this patent UNITED STATES PATENTS 1,300,823 Dickey Apr. 15, 1919 1,928,639 Berg Oct. 3, 1933 2,013,734 Prentiss Sept. 10, 1935 Y 2,029,337 Parker Feb. 4, 1936 2,122,504 Wilson July 5, 1938 2,212,004 Berthiaume et al. Aug. 20, 1940 2,375,834 Walker May 15, 1945 2,408,111 Truax et al. Sept. 24, 1946 2,530,269 Smith Nov. 14, 1950 2,546,965 Bodine Apr. 3, 1951 2,581,902 Bodine Ian. 8, 1952 2,611,992 Loy et al. Sept. 30, 1952 2,612,748 Tenney et al. Oct. 7, 1952 2,671,692 Matirko Mar. 9, 1954 2,738,334 Tenney et a1. Mar. 13, 1956 FOREIGN PATENTS 293,367 Great Britain June 28, 1928 996,216 France Aug. 29, 1951 OTHER REFERENCES Karcher (German publication), llune 11, 1948. (Copy in Library of Congress, Frames 8907-8911. Reel 83291.)

Technical Development Division, Summary of Activities Number 15, Federal Security Agency, Public Health Service, Communicable Disease Center, pages 71, 72 and 73, November 1, 1948.

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