US2966312A - Aerosol generator and lubricator and method of generating micronic size aerosol - Google Patents

Description

Dec. 27, 1960 J. A. WILSON, JR. ETAL 2,966,312 AEROSOL GENERATOR AND LUBRICATOR AND METHOD OF GENERATING MICRONIC SIZE AEROSOL Filed March 6, 1958 2 Sheets-Sheet 1 INVENTOR. JESSE A. WILSON, JR. MORLEY V. FR/EDELL ATTORNEY Dec. 27, 1960 J A WILSON, JR ETAL 2,966,312

AEROSOL. GENERATOR AND LU'ERICATOR AND METHOD OF GENERATING MICRONIC SIZE AEROSOL Filed March 6, 1958 2 Sheets-Sheet 2 I E I i! run: I WW HM In N h N A NN "W N HIEHH I INVENTOR.

JESSE A. WILSON JR. MORLEY v FR/EDELL ATTORNEY United States PatentQ AEROSOL GENERATOR AND LUBRICATOR AND F GENERATING MICRONIC SIZE Jesse A. Wilson, J12, Littleton, and Morley V. Friedell, Wheat Ridge, Colo., assignors to C. A. Norgren Co., Englewood, Colo., a corporation of Colorado Filed Mar. 6, 1958, Ser. No. 719,608

8 Claims. (Cl. 239-338) Our invention is directed to an apparatus for and a method of directly creating and generating a micronic size aerosol of lubricant in air without the use of settling chambers or the like and in particular to an aerosol generator for discharging into a compressed air line an aerosol of finely divided micronic sized particles of liquid lubricant in air wherein for all practical purposes all the liquid as it is discharged into the air stream is broken up into micronic sized particles.

As is well known, air line lubricators are for the purpose of discharging a fog of oil into an air stream for lubricating bearings, compressed air tools and various pneumatically operated devices and the generator of this invention, as will be explained, is to be incorporated as an element of the lubricator for creating such an aerosol. However, in actuality, to utilize the aerosol generator of this invention it is only necessary to supply compressed air or gas under pressure to the jet inlet of the generator, to supply liquid lubricant to the generator tubes formed integrally as a part thereof and to provide some sort of means for conveying the resulting aerosol to the point of usage. Bearing this in mind, it has been found desirable for the purpose of illustration and not limitation to discuss and show the teachings of this invention by in corporating the generator in the compressed air passage of a typical lubricator that includes the usual bowl for the liquid lubricant. Also hereinafter reference will be made to compressed air, air line, air under pressure, but it is to be understood that various gaseous mediums could well be substituted for the air under pressure and thus the invention is not to be limited by use of the quoted phraseology.

For the purpose of high lighting the advantages of this invention, perhaps at the outset a brief rsum of the conventional types or classes of air line lubricators should be provided. The first conventional type of lubricator known as the Mist or Fog lubricator, and hereinafter referred to as type A, really involves injecting a spray of lubricant into an air line through which compressed air flows and this will produce an aerosol of air and oil fog with the latter being composed of fine and coarse particles of lubricant. Contrary to the other type of lubricator which will be described hereinafter, type A does not contaminate or cause undesirable eifects in the main lubricant supply but it does create a relatively coarse fog in which at least 95 percent of the mist would be in particle sizes larger than two microns, with the major portion thereof being at least fifty microns in size. This heavy mist has a definite tendency to settle out in the flow lines, thus in effect delivering a large portion of the liquid in droplet or solid form and, of course, such is totally unsatisfactory in applications where a finely divided aerosol of micronic sized particles is required, such as for lubricating certain bearings, some air-driven devices, etc. On the other hand, type A of lubricator, as well as the other type to be discussed, has many advantages and commercial applications as evidenced by Cata- 2,966,312 Patented Dec. 27, 1960 log 800 of the C. A. Norgren Co. of Englewood, Colorado.

The other type of conventional lubricator, hereinafter referred to as type B, does provide an aerosol of micronic sized particles, but as illustrated in several United States patents, a few of which are hereinafter identified, a good part of the oil that is initially fed to and intermingled with the air stream following atomization is directed against a baflle or the like and then discharged into a settling space or chamber whereby the large oil particles are returned to the lubricant reservoir and the fine, light or micronic sized particles are carried by the air stream to the point of usage. In other words, the micronic sized particles, never more than about 5 percent of the total liquid initially sprayed or atomized, pass through the outlet of the lubricator to the point of usage while the remainder of the liquid comprising the heavier particles rejoin the main liquid supply and are recirculated over and over again through the same cycle. Thus, when using compressed air for instance, the liquid lubricant would be aerated an average of twenty or more times before it was all consumed. Actually, initially with the lubricant bowl full the liquid would not have been aerated at all, but as the reservoir was being emptied the liquid would have circulated many times.

This latter aeration in type B causes undesirable effects in many lubricating liquids. For example, with ordinary lubricating oils, aeration increases the rate at which the oil atomizes so that aerosol output may well increase percent or more as the liquid supply lessens which obviously is quite a factor, such as when a constant delivery is most desirable or necessary for good lubrication. Aeration also causes oxidation which, in the case of compounded lubricants, may cause them to completely or at least partially lose their important characteristics and thus operating specifications will not be met. Specifically, oxidation will usually destroy the functions of rustproofing liquids, de-oxidizers, deodorants and other like compounds and these defects usually occur afterthe liquid has circulated only a few times and has become well saturated with air. It should be mentioned that type B of lubricator does result in the fine micronic sized particles being truly air borne, which is a definite advantage in that they will not drop out of the air stream as coarse particles do and they may be transported properly to the point of usage. At the point of application or usage of such an aerosol for lubricating certain tools and other devices, if necessary, the aerosol may be passed through a reclassifier or condensed to form larger particles to increase wetting characteristics, all in a manner well known in the art.

It now has been determined that there are many usages, such as in connection with high speed bearings, where the aerosol fed thereto for lubricating must be solely of the type including micronic or small, finely divided oil particles as unless the particles are maintained in such condition when applied certain difiiculties will result, such as a chatter of the bearings. Obviously type A falls short in this respect, but in many instances type B is satisfactory for this purpose, although there are definite limitations, one being that the lubricator must be utilized in such a manner that it is undisturbed. By the latter expression it is meant that the lubricator is not intended to be jostled about or exposed to substantial amounts of movement caused by rapid deceleration or acceleration or momentarily inverted from its normal upright position whereby it would not have the continual assistance of gravitational forces to effect the separation of the coarse particles from the usable aerosol. Many of these last named actions would obviously occur to lubricators incorporated in aircraft, missiles, rockets and 3 in many well known mechanical devices, such as jack hammers, where it is impossible during operations to be concerned with attitudes and inertial forces. For example, if type B lubricator were suddenly turned over or even exposed to partial rotational movements, there would be slopping of the liquid lubricant and it would be hour, uniformly and constantly supplied by aerosol, is

necessary for successful operation or in other words lubricant must be delivered uniformly and without fluctuation, even at extremely low flow rates. The second type of conventional lubricator cannot meet such conditions as the supply of lubricant needed is too great,

due to the number of times aeration of the liquid takes place, as explained, and furthermore the amount of mist delivered is not uniform, due to repeated aeration of the lubricant. Also there are instances where the amount of liquid atomized must be constant, irrespective of 'air pressure, and the prior types of devices are incapable of so functioning. There are conventional types of aerosol generators which deliver a flow of even 2 minims per hour in a series of widely spaced spurts (several minutes apart),'but such would result in the high speed bearing of the type mentioned burning out during the periods of no lubrication delivery. On the other hand, if the lubricant flow is increased to the point where relatively constant delivery is obtained, the bearing overheats and burns out because of churning and friction of the excess lubricant.

Bearing the above in mind, the aerosol generator of the present invention overcomes the limitations of the prior art and conventional type lubricators discussed and results in creating directly an aerosol of finely divided micronic sized particles of liquid in air without causing undesirable effects to the lubricant as the liquid upon being discharged into the air stream is completely broken up into micronic sized particles and at the same time the generators, illustrated hereinafter, result in a limited and uniform oil feed and are completely independent of any normal movements or attitudes. Specifically, the aerosol generator of this invention is unaffected in operation, regardless of any normal attitude to which it is exposed, it guarantees a constant, uniform, nonfiuctuating and predictable supply of lubricant aerosol irrespective of the air pressure or velocity, it does not contaminate or aerate the liquid supply prior to the atomization thereof, and most important it creates directly and as the lubricant is discharged into the air streama uniform aerosol of micronic sized particles of lubricant which are substantially 100 percent airborne and thus may be carried to the point of usage without settling out.

Thus it is an important object of this invention to provide an aerosol generator which creates directly and for all practical purposes nothing but an aerosol of finely divided micronic sized particles of liquid lubricant in air.

Another object is to provide such an aerosol generator which may be operated in any normal attitude and under any normal inertial force and wherein all of the liquid as it is discharged into the air stream is broken up into a predictable supply of micronic size particles, such as those measuring two microns or less.

A further object is to provide an aerosol generator which may be incorporated as an element in a lubricator and which overcomes the outlined problems and difficulties of prior type lubricators.

Yet another object of this invention is to provide an aerosol generator wherein the amount. of liquid atomized 4 is constant, irrespective of the pressure and velocity of the compressed air supplied to the generator.

The method of creating an aerosol as defined is another important object of this invention.

Other objects and advantages of the invention will become apparent by referring to the following detailed description in conjunction with the drawings wherein several embodiments of the invention are illustrated, wherein like numerals and primes thereof represent similar elements throughout the figures and wherein:

Figure l is an enlarged cross sectional side elevational view illustrating an aerosol generator of the invention in corporated in position in an air conduit of an aerosol lubricator;

Figure 2 is an enlarged sectional view of the generator illustrated in Figure 1;

Figure 3 is a sectional view taken along the lines 3-3 of Figure 2; v

Figure 4 is an enlarged view taken along the lines 4-4 of Figure 2;

Figure 5 is an enlarged view partly in section similar .to that ofFigure 3 but incorporating four generator tubes instead of two;

Figure 6 is an enlarged cross section of aportionof a typical bypass type aerosol lubricator incorporating the principles of this invention;

Figure 7 is a sectional view taken along the lines 7--7 of Figure 6;.and

Figure 8 is a sectional view taken along the lines 8-8 of Figure 6.

Referring to the drawings in detail, it should be pointed out at the outset for the sake of uniformity of language and a clear understanding of the invention that the expression aerosol or airline lubricator refers to the assembly including a body having air inlet and outlet means, a lubricant bowl sealed to the body and the.generator of this invention, while the expression aerosol generator refers to structure of the type illustrated in Figure 2. Furthermore, the parts of the lubricator, other than the essential components of the generator element, may assume various forms and shapes. Thus it is to be understood that the partial lubricator structures illustrated in Figures 1 and 6 are merely typical of various types that may be employed and modified to include the aerosol generator of this invention. In this same con nection, reference is made to C. A. Norgren et al. U.S. Patents 2,718,934 and 2,661,814, Faust U.S. Patent 2,751,045 as well as many other U.S. patents owned by the assignee of this invention as illustrating air line lubricator bodies in general which, as will be aparent, could easily be modified to include the teachings of this invention. For example, the generally vertical rotatable lubricant metering assemblies or venturi plugs of the said patents would be replaced by the instant aerosol generator. It will also be recalled that mention was made that settling chambers were frequently needed prior to the present development, and in this connection reference is made to the settling chambers or spaces provided by the diffusion plugs 22 and 42 of Patents 2,718,934 and 2,751,045.

Considering now the embodiment of Figures 1 to 4 inclusive, the true invention is depicted by the aerosol generator generally represented at 1 as well as the method of generating a micronic size aerosol by the use thereof in combination with an air passage and lubricant supply and the combined aerosol lubricator formed by incorporating the generator with the lubricating bowl and air passage. Basically the generator utilizes several natural liquid phenomena including capillary attraction, wetting v cylindrical air conduit 4 having a threaded inlet 5 and a threaded outlet 6 for respectively receiving in threaded engagement compressed air supply line 7 and aerosol discharge line 8. By means more completely shown in some of said prior patents, such as, the clamp ring 11 in Patent No. 2,718,934, the under surface of body 3 is provided with an annular or peripheral gasket 9 for effecting a fluid seal between body 3 and lubricator bowl 10, the latter containing a suitable supply of lubricant L.

As shown, bore or conduit 4 is actually stepped to provide annular shoulder means 11 and at substantially the longitudinal center of bore 4 there is provided in body 3 a ring-like or annular groove 12. At approximately the bottom surface of body 3, as viewed in Figure 1, there is provided a circular slot 13 communicating with groove 12 and within which is supported, by any suitable means such as a friction fit, the top end of a liquid oil supply tube 14 which thus communicates with groove 12 and the lubricant within bowl 10. A fixed or adjustable restriction of types well known in this art may be provided in tube 14 to aid in control of the flow of liquid from bowl and as shown an adjustable restriction may take the form of a piece of ordinary felt 15 constituting capil lary or wick means at the top end of tube 14. Capillary means 15 can be adjusted by compressing and modifying the tip end of tube 14 to provide a capillary bore would be an example of a fixed restriction. Further, for a purpose that will be more fully described hereinafter, there is provided liquid pressurizing means in the form of orifice 16 communicating between bore 4 and the interior of bowl 10.

The aerosol generator 1 is illustrated, due to the configuration of bore 4, as comprising a round or cylindrical body 20, of brass for example, having front wall 21 and rear wall 22 and being of a diameter to be detachably received in bore 4 with wall 22 abutting shoulder 11. Of course, body may assume various shapes and it is desirable that generator 1 be removable from bore 4, such as for cleaning purposes, and thus any suitable means such as a snap ring 23 engages the front wall 21 to detachably hold the generator in the location illustrated in Figure 1. Substantially at the longitudinal center, body 20 is provided between walls 21 and 22 with an air jet inlet 24 of a size to pass the desired amount of incoming compressed air, which in turn communicates with an expansion chamber 25. At diametrically opposed points body 20 is provided with acute angled bores 26 which extend from the exterior peripheral surface 27 of body '20 to chamber 25. Positioned by any suitable means (such as a friction fit) within each bore 26 and extending therefrom into chamber is a generator tube 28 also constructed of any suitable material such as brass. One end of each tube 28 is flush with surface 27 and each of the diametrically opposed tubes is provided therethrough with a capillary bore 29 generally not more than .015 inch in diameter.

The generator tubes 28 constitute an important part of this invention and although such may assume various forms in body 20, Figures 1 to 4 inclusive do illustrate a preferred arrangement of these tubes as a result of experience and various tests. Measured from the axis of bore 24, the preferred angle of each bore 26 and in turn tube 28 is approximately 45 degrees, but such may easily vary from 30 to 60 degrees. As is apparent, tubes 28 have portions 30 which extend within chamber 25 and the tips of these portions are spaced from one another a rather critical amount and this will be discussed hereinafter. Assuming that the walls of tubes 28 intersect at a point adjacent inlet 24, then it is preferable that this intersecting angle of the tubes be located a distance from inlet 24 equal to one and one-half to two times the diameter of jet inlet 24. At the inner end or tip of each portion 30 a narrow groove 32 parallel to the longitudinal axis of body 20 is milled so that each groove 32 has its longitudinal axis in axial alignment with air from inlet 24. As illustrated particularly in Figures 2 to 4, each groove 32 has sharp, square corners at the bottom there'- of, is preferably about .010 inch wide (slightly less than the diameter of bore 29) and a depth of about .008 inch. The last named depth is primarily used if the jet inlet 24 is roughly of a size illustrated and for larger size jet inlet diameters the depth of each groove 32 would be proportionately increased, say to a maximum of .016 inch. At each side of groove 32, the exterior surface of portion 30 is backed or milled off at preferably at 45 degree angle as illustrated at 33 to provide close to knife-like edges 34. Such a structural arrangement results in a needle-like point being formed at 35 at the tip of each generator tube.

It is to be understood that the scope of the invention is intended to cover an aerosol generator having one tube and more important one groove or capillary surface 32 but, of course, Figures 2 and 3 illustrate a pair of generator tubes 28 and such has been found very satisfactory. Also, additional tubes may be employed, such as the two pairs of equally spaced and diametrically opposed tubes 28' illustrated in Figure 5. In other words, one or various numbers of generator tubes may be used and for extremely low flows it is preferable to utilize the structure of Figure 3 but to block off one tube 28 whereby such will only be used as a dummy to balance air flow.

Hereinafter throughout the specification and claims there will be utilized the expression capillary surface and such has reference to groove 32. As is well known, a capillary bore or wick or even some dry powders would constitute particular types of capillary surfaces, the bore being open at both ends and generally formed from a cylindrical surface of small radius of curvature. Groove 32 is likewise opened at both ends and formed from a surface in channel form whose width is comparable in size to the diameter of a capillary sized bore. Thus, the expression capillary surface is meant to include structure that functions to provide capillary attraction manifest in the phenomena of surface tension. Previous reference has been made to any attitude and by this is meant any normal attitude or position generally anticipated in, for example, an airplane. Of course the present invention will be installed in an upright position as illustrated in Figure 1, but it may be subjected to normal disturbances without affecting the operation thereof.

The essence of this invention resides in having the compressed air stream travel over a capillary surface which in the drawings is in the form of groove 3-2 as such results in the aerosol of air and, for all practical purposes, percent finely divided micronic particles of lubricant. However, other designed capillary surfaces may be utilized and are intended to come within the scope of this invention, although groove 32 is preferred. As will be explained, it has been found that needle-like point 35 and knife-like edges 33 greatly aid in providing such an aerosol. To accomplish the feature of having a constant, uniform and predictable amount of atomization of liquid lubricant it is necessary to have capillary means directly communicating with groove 32 for feeding liquid lubricant to the latter. Although, for example, wick means could be utilized, the capillary means preferably takes the form of a capillary sized bore 29' of a diameter slightly larger than the width of groove 32-. In this same connection felt 15 is merely a convenient means for causing lubricant to enter bore 29 and as a matter of fact a capillary sized bore could readily be substituted therefor. Further, it might be desirable to have wick means throughout tube 14 as such would be advantageous in active attitudes to prevent any air pockets or the like forming in tube 14.

The embodiment of Figures 1 to 4 inclusive might well operate as follows, assuming air under suitable initial supply tube 14 by virtue of the lower pressure existing in reduced section 25. It will be noted. that each bore 26 is substantially coextensive with groove 12 and as soon as the oil reaches groove '12, the liquid will then enter each of the capillary bores 29 and travel towards the tips of portions 3%. Once the liquid has started to enter each bore 29, such will continue to do so until the bore 29 has not only been filled but also each groove 32 is filled to a meniscus. Thus, once primed, the filling of grooves 32' will occur whether there is any pressure on the liquid L or not, this being due to the capillary action that takes place. Of course, other types of liquid feeds may be employed but to have the flow at a truly steady .and constant rate independent of air velocity, capillary or wick type feed means are necessary, as explained.

As the air pressure is increased, the velocity through jet tube 24 increases and it starts to blow the oil off generator tubes 28 and when a pressure of about 3 p.s.i. is reached, the velocity is high enough that the liquid in grooves 32 will have been blown into a thin a few millionths of an inch thick. This film is then blown offthe trailing edges (the edges most adjacent wall 22) of grooves 32 and thereby all of the film is broken up into micronic sized and finely divided particles of lubricant. Any larger particles or droplets that might ,collectby running over the edges of grooves 32 run down thefaces 3 3 to the needle-like points 35 where they are broken up into similar micronic sized particles. Thus all liquid discharged into the air stream is broken up into micronic sized particles. As the liquid film is blown offthe trailing edges of each groove, surface tension and wetting attraction keep feeding the liquid onto the capillary surfaces of the grooves 32 and capillary attraction keeps the capillary tubes 29 filled up and supplying liquid to the capillary surfaces or grooves 32. Each capillary tube or bore 29 feeds the liquid very-uniformly, without any tendency for the contacting meniscus to cavitate where it is entering a groove 32 and thus cause a fluctuatingflow. Even under increased or varying pressure and quite high fiow rates of compressed air the same uniform delivery of micronic sized particles exists due to the capillary means 29 directly feeding each capillary surface 3-2. The molecular attraction and surface tension of the liquid film prevents it from being blown oil the surface of the grooves 32 or being blown too thin or broken. Tubes 28 are disposed in the jet air stream approximately as shown in the various views, as close to the center of the jet as practical without touching, allowing a minimum of about .008 inch separation. This configuration does not create any siphoning or venturi effect, maintaining, in effect, a neutral or balanced pressure at the exit of the capillary bores 29. This further allows prefect feeds of liquid, unaffected by the velocity of air flow, resulting in more precise control of liquid output. Each groove 32 channels the air flow and reduces the agitation thereof, eliminating any tendency for the liquid meniscus at the end of bores 29 to cavitate. Of course the expansion chamber 25 slows the travel of the air stream and aids in uniformity of travel of the aerosol. Repeating, the operation has been described with reference to two generator tubes 28, but the operation of an aerosol generator with one generator tube or four, as illustrated in Figure 5, should be apparent. In. actual operation, the principles of this invention have been utilized for uniformly and without interruption delivering lubricant flows as low as two-thirds minim per hour.

Considering Figures 6, 7 and 8, such has been illustrated merely to point out one of the many modified uses of the principles of this invention and in this instance 'a pair of generator tubes are positioned in parallel spaced relationship. Patent 2,442,777 wherein there is illustrated an aerosol .lubricator of the bypass" type. Referring to this patent, the incoming air flows through opening 32 and during :normal conditions the flap valve 29 would be closed, but

Reference is made to the C. A. Norgren when the pressure of the incoming .air is increased sufficiently the flap valve will be opened to provide a bypass line and such an arrangement is often desirable to ac .commodate changes in required air volume and at the same time minimize any change in air flow through 32. .In Figure 6 there is merely disclosed a very small portion of the lubricator unit with numeral 40 representing a section of the body casting and there being provided a suitable casting 41 forming with body 40 the air flow line .42 which is comparable to the normal flow passage 32 of said last named patent. Between casting 41 and the bottom of housing 4am viewed in Figure 6, there is provided the flap valve 43- which would normally be closed and which would open upon suflicient air pressure being applied to bypass line 44. The top of casting 40 is provided with a'slot 45 and supported therein by any suitable means, such as the O-ring arrangement 46, is the generator unit 4-7 which is quite similar to generator 1 previously described. This unit47 includes a'circular body having a pair of generator tubes 48 similar to tubes 27 arranged in parallel spaced relationship instead of being diametrically opposed and each, of course, is provided .with portions 49 similar to portions 30 extending in expansion chamber 50, the latter in turn communicating with outlet 51. Body 48 is likewise provided with a pair of passages 52 and 53 comparable to previously described jet inlet 24 for directing the incoming air to tip portions 49 and of courseeach tube 48 has .a capillary sized bore 54 terminating in a capillary surface or groove 55 similar to groove 32. The operation of the apparatus of Figures 6, 7 and 8 including generator 47 should be apparent in .view of the detailed description in connection with Figure 2. The same type of aerosol including air and percent finely divided micronic oil particles is formed, this embodiment only being illustrated to show that the aerosol generator principle of this invention as well as the method of forming a micronic size aerosol by the use thereof may be incorporated in various lubricators and furthermore the generator tubes may be arranged in various patterns and, as mentioned, only one may be necessary in some instances.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated embodiments, may be made .within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. An aerosol generator comprising a body portion including'a passage for the flow of compressed air therethrough with an inlet and outlet communicating with the passage, a tubular member communicating at its one end with a source of liquid and the opposite end thereof being disposed in the path offlow of the compressed air through the passage, the opposite end including a capillary sized groove, the groove being aligned .with its longitudinal axis corresponding to the substantial direction of air-flow through the passage whereupon the compressed air flowing across the grooved end is operative to break up the liquid into rnicronic-sized particles for removal through the outlet.

2. An aerosol generator comprising a body portion including a passage with inlet and outlet means for theflow a source of liquid, a passage definingan expansion chamher communicating with a restricted inlet and a relatively large outlet, a generally tubular member of capillary dimensions communicating at its one end with the source of liquid and its opposite end projecting into the path of flow of compressed air through the expansion chamber, the opposite end including a capillary sized grooved portion aligned with the direction of flow of compressed air through the passage, whereupon liquid delivered through said tubular member into the groove portion is divided into minute particles by the flow of compressed air thereacross for delivery through the outlet.

4. An aerosol lubricator according to claim 3 wherein there is provided a pair of tubular members with the grooved portions on each positioned in diametrically opposed, spaced relationship in the expansion chamber.

5. In an aerosol generator having a source of liquid together with a passage for the flow of compressed air therethrough, a generator tube of capillary dimensions communicating at one end with the source of liquid and with the opposite end of said generator tube projecting into the path of flow of compressed air through the passage, the opposite end including a grooved portion of capillary dimensions with the longitudinal axis of the groove being directed in the substantial direction of flow of compressed air through the passage.

6. In an aerosol generator adapted to receive a liquid lubricant and having a passage extending through the generator for the flow of compressed air therethrough, a generator tube defined by a bore of capillary dimensions including an inlet end communicating with the source of liquid lubricant and an outlet end projecting into the path of flow of compressed air through the passage, the outlet end including a grooved portion of capillary dimensions and with the longitudinal axis of the groove disposed in the substantial direction of flow of compressed air through the passage, the side edges of the grooved portion terminating in knife-like edges and the trailing ends of the grooved portion forming an acute angle with the longitudinal axis of the groove.

7. In an aerosol generator adapted to receive a liquid lubricant and having a passage for the flow of compressed air therethrough, a generator tube defined by a capillary bore disposed with its inlet end communicating with the source of liquid lubricant and with the outlet end projecting into the path of flow of compressed air through the passage, the outlet end terminating in an elongate groove aligned with its longitudinal axis in the substantial direction of flow through the passage, the width of the groove being of a size less than that of the diameter of the capillary bore and with the sides of the groove terminating in trailing ends of substantially needle-like size whereupon the flow of compressed air through the passage is at a velocity such that liquid lubricant delivered into the groove is blown into a fine film and broken up into finely divided micronic-sized particles for delivery with the air through the passage.

8. In an aerosol generator comprising a source of liquid lubricant and having a passage including inlet and outlet means for the flow of compressed air therethrough, a plurality of generator tubes positioned in even, spaced relation into the passage, each generator tube being defined by a capillary bore projecting angularly into the passage in the direction of flow of the compressed fluid, each bore including an inlet end communicating with the source of liquid lubricant in the generator and an outlet end which is tapered for alignment in parallel relation with the longitudinal axis of the passage, the outlet end of each bore including a grooved portion extending thereacross in communication with the bore with its longitudinal axis disposed to correspond with the direction of flow of compressed air through the passage, each grooved portion having a width less than the diameter of the respective capillary bore and with the sides of the groove terminating in knife-like edges and the trailing, downstream ends of each groove terminating in needle-like points whereupon the flow of compressed air across the capillary groove surfaces will cause liquid lubricant delivered onto the groove surfaces to be blown into a fine film and divided into micronic-sized particles at the trailing ends thereof for delivery in the form of a fine mist with the compressed air through the outlet end of the passage.

References Cited in the file of this patent UNITED STATES PATENTS 883,374 Akeson Mar. 31, 1908 963,985 Best July 12, 1910 1,112,025 Nelson Sept. 29, 1914 1,204,309 Peterson Nov. 7, 1916 2,353,865 Armstrong July 18, 1944 2,439,910 Snyder Apr. 20, 1958 2,826,400 Sterner et a1. Mar. 11, 1958 2,889,009 Endebak et al. June 2, 1959 2,906,463 Curry Sept. 29, 1959 FOREIGN PATENTS 890,830 France Feb. 18, 1944

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