US3722759A

US3722759A - Explosion proof aerosol can

Info

Publication number: US3722759A
Authority: US
Inventors: J Rodden
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-11-17
Filing date: 1971-11-17
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27
Also published as: DE2314912A1

Abstract

Explosionproof aerosol can. Depressing spray head against coil spring surrounding delivery tube in normal operation moves discharge port in said tube below surrounding valve body, permitting discharge of container product. Excess pressure acts on large area annular face of surrounding valve body and on coil spring to compress yieldingly resilient composition in valve housing, thus moving valve body so as to expose discharge port.

Description

[ 1 Mar.27, 1973 3,005,577 10/1961 Webster...............................222/397 [54] EXPLOSION PROOF AEROSOL CAN [76] Inventor: Joseph P. Rodden, 60 Jarrett Lane,

Hatbom, p 9040 Primary Examiner-Robert B. Reeves Assistant Examiner-L. Martin Nov. 17, 1971 Appl. No.: 199,501

Att0rneySynnestvedt & Lechner [22] Filed:

ABSTRACT Explosionproof aerosol can. Depressing spray head against coil spring surrounding delivery tube in normal operation moves discharge port in said tube below surrounding valve body, permitting discharge of container product. Excess pressure acts on large area an nular face of surrounding valve body and on coil 5 53 3ZH39M 2354 wmumuw 2652 92 7O 2 34 5 1 5 ..I

7 u ABM-Mm w3 9 N5 5 nfi fl6 mu 5 m mm "ML. m gm 1 T M C lo U IF spring to compress yieldingly resilient composition in [56] References Cited valve housing, thus moving valve body so as to expose discharge port.

UNITED STATES PATENTS 2,686,652 8/1954 Carlson et al.....................251/353 X 15 Claims, 9 Drawing Figures V ZW/V M/ w i l4 ilent 8 2 #1, e L 2 i E mm 0 9 R vkM PATENTEE MAR; 7 ms INVENTOR PAUL RODDEN JOSEPH EXPLOSION PROOF AEROSOL CAN The present invention relates to a safety closure member for cans containing fluid under pressure, commonly referred to as aerosol cans. The product contained within the can is easily discharged by mild (finger) pressure applied externally against the spray head, which surmounts the can. This pressure depresses a delivery tube, which is so configured as to established a channel, on being depressed, through which the contents of the can may be released in the desired amount through a nozzle in the spray head.

' Although light thumb pressure on the spray head, from outside the can, is sufficient to open the discharge line, pressure stored within the can must be prevented from opening a discharge channel, under normal conditions, lest the product escape. Aerosol cans are conventionally made quite strong enough to retain the pressure imposed in loading them. But a number of accidents have followed the explosion of aerosol cans, usually when they have been exposed to elevated temperatures which increase the pressure within the can.

Various proposals have been made to provide means for relieving pressure within an aerosol can whenever it exceeds a safe value. Most of these proposals entail such costly problems as to have hindered their adoption. Opposed springs, for instance, make final assembly intricate and expensive, in addition to material cost. Weakness zones are difficult to create to precise tolerances, and once they rupture, the entire contents of the can will be blown out, far and wide. Furthermore, proposals which involve any break in the internal finish of the can will render it unacceptable for many products because the exposure of even a scratch through the protective film (i.e., the internal coating) may permit corrosion, or metallic contamination of the contents.

Since aerosol cans are completely expendable, and are not intended ever to be reused, it is obviously necessary that any valve mechanism associated with them shall be an insignificant factor in the overall cost of the product. The present invention contemplates the provision of a valve mechanism for use in a conventional aerosol can which mechanism not only performs all normal operations of the spray head and discharge tube, but also will open under abnormal pressure con ditions within the can to relieve that pressure, and, in addition, will restore the valve to its normal closed condition when the excess pressure has been relieved.

The mechanism for this purpose, in its preferred embodiment, includes a stem which is preferably made of plastic by injection molding a process which is very inexpensive, rapid, and completely accurate in result. The mechanism includes an outer valve body, which surrounds the stem and is in turn encased in a thin shell. These parts can be extruded or otherwise produced, as by molding or shaping techniques. The shell is housed in the valve cup of a conventional form of aerosol, can top.

The mechanism provided here is simple and effective in its operation, inexpensive to manufacture, easy to assemble and install, and proof against accidental discharge. Furthermore, its self-reclosing feature ensures that the entire contents of the aerosol can will not be needlessly dissipated. Still further, the valve assembly is installed without risk of breaking the inner protective film which coats the metal of the can and shields the product from metallic contamination.

One of the significant features of the present device is the provision of an inner chamber, above the valve body but within the valve cup in the can top, which contains a yieldingly resilient composition. If abnormally high pressure conditions arise within the can, such pressure will act on the exposed annular surface of the valve body and drive it upwardly against the resistance of the coil spring and the resilience of the composition in the chamber, until the port in the wall of the delivery tube is exposed. Thereupon excessive pressure within the can is able to escape through the tube to atmosphere.

It will be noted that the valve stem can easily be moved manually, but only in a downward direction, under normal operating conditions. Such movement requires only light finger pressure against the spray head. The valve cup which houses the valve assembly, fixes the stem and associated parts against upward movement except under severe pressure conditions, which then drive the valve body to pressure relief position, as previously described.

How these and other objects which are incident to my invention are attained will become more evident from a consideration of the accompanying drawings, and the remarks which follow. These relate to an embodiment of the invention which is presently preferred where very tight sealing is important. They also disclose an alternative embodiment, which may be preferred where very tight sealing is not essential.

Turning now to drawings:

FIG. 1 is an elevational view, partly in section, of an aerosol container equipped with a product dispensing valve constructed in accordance with a preferred form of the invention;

FIG. 2 is a vertical sectional view of the dispensing valve and the associated cap of the container;

FIG. 3 is a plan section, on an enlarged scale, taken on the line 3-3 of FIG. 2;

FIG. 4 is a further enlarged view, partly in section, of the lower portion of the valve stem of FIG. 1;

FIG. 5 is a plan section taken on the line 55 of Fig.

FIG. 6 is an elevational view of the valve stem of FIG.

FIG. 7 is an elevational view of a modified form of valve stem;

FIG. 8 is a plan section taken on the line 8-8 of Fig. 7; and

FIG. 9 is a vertical sectional view of an alternative embodiment of the invention.

A conventional aerosol can is indicated by the reference numeral 10 in FIG. I. This can has, however, been equipped with the valve mechanism identified as a whole by the reference number 1 l, which embodies the present invention. The valve mechanism 11 is mounted in the valve cup 12 of relatively conventional form. This is united by the skirt 13 to the corresponding curl structure 14 on the can 10.

It is customary in this industry for the can manufacturer to provide the valve cup 12, which is configured to mate with the can 10 which that manufacturer produces. The cups are usually sent to the valve manufacturer, who installs the valve mechanism, and returns them to the can packer for attachment to the cans after filling.

The valve mechanism of the present invention is installed in the valve cup 12 by mounting it in a centrally positioned housing 15, known in this art. as the pedestal. This is shaped like an inverted cup and is formed in the valve cup 12 in any convenient way. The outer shell 16 of the valve is firmly fitted into the pedestal 15 in the valve cup structure 12, and is crimped in place, forming an inwardly extending ridge or rib 17.

Before the pedestal 15 is crimped into engagement with the valve, the parts of that valve must be assembled. This is one of the areas in which the prior art has encountered the greatest difficulty. It is easy to describe balanced spring arrangements and other pressure resisting mechanisms, but it is extremely difficult to bring reacting elements together into a single compact assembly, which can be easily and accurately posi tioned within the valve shell 16 and mounted in the pedestal or housing 15 of the valve cup.

How this is to be accomplished is illustrated generally in FIG. 2. Within the outer shell 16 which surrounds the valve body 18 the central stem 19 is provided. This stem has a solid central core 20 (see FIG. 3) which has, evenly spaced about its periphery, a'plurality of vertical channels 21 here illustrated as being three in number. The outer surface of this tubular stem element is cut away to provide a cylindrical extension 22 of smaller diameter than the stem 19. A low pressure coil spring 23 surrounds the cylindrical extension 22 and lies within the outer diameter of the stem 19. The valve body 18 has an arbor 24 in which the lower portion 22 of the stem 19 is slidably housed. The stem 19 slides in the bore 18a in the valve body, and the valve body slides in the bore 18b in the valve shell. A groove 25 is formed inside the valve body 18. This extends radially outwardly from the arbor 24, and is configured to receive a resilient sealing washer 26 which snugly fits therein and also snugly surrounds the lower portion 22 of the stem 19.

The stem extension 22 passes through the opening in the washer 26 with some distortion of the material of that washer. The extreme end of the stem 19, or more properly of the extension 22, is shaped to provide an outwardly flaring lip or flange 27 which reduces to a feather edge which snugly engages the lower face 28 of the valve body 18. This flange 27 is sufficiently flexible to be pushed through the opening in washer 26.

One of the advantages of the present invention is the ease with which the valve mechanism is assembled. The sealing washer 26 holds the coil spring 23 in position around the narrowed extension 22 of the valve stem 19. The valve body 18 not only is positioned, to some extent, by the sealing washer 26 in the groove 25; it is also held in place by reason of the flange 27, which, during assembly, is simply pressed through the opening in the washer 26 and the arbor in the valve body 18, compressing the spring 23 in the process, until the feathered edge has passed below the bottom of the valve body 18. Thereupon the flange springs back into place, engaging the pressure face 28 of the valve body 18.

The annulus 29 of resilient material is so configured that its outer diameter snugly fits the inner diameter of the shell and the inner diameter of the annulus fits the outer diameter of the valve stem 19. The sealing washer 30 is then slid over the enlarged head 31 of the valve stem 19,just below the beveled shoulder 32, so that the valve shell, valve body, spring, and lower sealing washer are all frictionally held between the upper sealing washer 30 and the lower sealing flange 27. This convenient unit can readily be inserted in the pedestal 15, and firmly locked in place by crimping the pedestal to form the inwardly extending rib or ridge 17.

A significant aspect of the preferred embodiment of the present invention is the provision of a solid central stem for the valve which can be mounted between two spaced apart sealing washers, to afford increased security against leakage. This form of the device, which is illustrated particularly in FIGS. 3, 4, S and 6, is quite inexpensively produced by injection molding, both accurately and in quantity. Considering this in more detail:

FIG. 3 is a sectional view in plan, taken near the top of the valve stem. At this point, which is at about the same plane as the lower rim of the spray head 33, the stem consists essentially of a tubular body 34 having circumferentially spaced vertical ribs 35 extending radially inward from its inner wall. These ribs are so spaced as to provide channels 21 between them, which extend vertically throughout the upper portion of the stem, to a level 36 which marks a transition in the delivery path. The number of ribs and flow channels may be varied if desired. Only three are here shown, in the interest of clarity and simplicity.

At the level 36 the ribs 35 merge with a solid central core 20, the top which is seen as a full circle in FIG. 3. The flow channels 21 open out, slightly below the transition plane 36, as best seen in FIG. 5, while the ribs 35 interconnect the upper portion of the

valve stem

19,22 with the lower portion 19'.

This is more clearly seen in FIG. 4, where a portion of one of the flow channels 21 is seen in full lines above its transition point 36. The lower portion 19' of the valve stem is a solid right cylinder, except for the provision of flat surfaces, oi lands, 37, equally spaced apart about the periphery of the stem end 19, each preferably being directly below the lower end of one of the flow channels 21. It will be noted that the lower edge of the flat lands 37 is above the bottom of the stem end 19', so that no product escapes until the stem is depressed.

The pathway for escaping product is indicated by the dotted arrows 38 and the solid arrows 39. Briefly, gas passes below the lower rim of the arbor 24 in the valve body 18, when the stem 19 is depressed sufficiently. It passes through the segment-shaped openings provided between the cylindrical inner surface of the bore 24 in the valve body and the flats 37, here'illustrated as being three in number. As the arrows 38 show, the flow path is through the channels 21 via the flatted portions 37. Through this means product reaches the spray head 33 and is discharged through the spray nozzle 40.

It will be seen from FIG. 5 that the solid central core 20 of the valve stem, together with the lobes or ribs 35, which are integral with the core in this zone, provides quite a substantial structure at the plane of that figure, notwithstanding the fact that some flow channel area still remains between the ribs 35. Thus a configuration of ample structural strength is assured.

An elevational view of the completed valve stem just described is seen in FIG. 6. The spray head 33 has not been illustrated in this figure, nor any of the other environmental structure.

FIG. 7 illustrates a somewhat modified form of valve stem, in which the stern itself may be made of metal instead of plastic. In this modification, an axial passage 41 extends throughout the upper stem, thus dispensing with the ribs 35 and the flow channels 21. The tri-lobal central core illustrated in FIG. 5 is replaced by radial webs 42 (see Fig. 8). These webs, being of metal, afford sufficient strength and rigidity to serve as the only connection between the

upper portion

19,22 of the stem and the lower portion 19. How the flat lands 37 afford communicating passages within the inner diameter 24 of the valve body is clearly seen in FIG. 8, which is a sectional plan view on the line 8-8 of Fig. 7. When this construction is employed, the resilient flange washer 27 is applied separately to the lower face of the stem end 19', using any appropriate means to secure it in place.

Substantially the same configuration could be injection molded of plastic. If this were done, the webs 42 might extend radially outwardly from the arc of the central arbor 41 or could have their side walls substantially tangential to it, as here shown.

Still another embodiment of the invention is illustrated in FIG. 9. In this embodiment, as in that shown in FIGS. 7 and 8, the inwardly extending vertical ribs 35 are omitted. The flow channel through the valve stem is an axially extending passage 43.

The stem 19 is stepped at its lower portion to provide an extension of reduced diameter 22 to hold the spring, as in the embodiments previously described. However, in the greatly simplified device shown in FIG. 9 various items are omitted. The lower beveled shoulder 32', the lower stern and 19', the groove 25 and the sealing washer 26, present in the other embodiments of the invention, are not incorporated in the structure of FIG. 9. This can be quite safety done where the can isto be used with a low-pressure charge or with a low-volatile product. Alternatively, it can be done with a high pressure charge and a high viscosity product.

Near its lower end, the wall of the extension 22 is provided with a plurality of ports 44 (here shown as four in number) so positioned as to ensure that when the stem 19a is depressed these ports will communicate with the interior of the can at a level below the lower surface 28 ofthe valve body 18.

Except for the omission of the lower sealing washer, the embodiment of the invention just discussed is quite similar to the previous disclosure, but it does include an additional feature, now to be described.

Where the contents of an aerosol can subsist primarily in the form of vapor, the embodiment shown in FIG. 2 is ample for the need. But there are occasions when it is desirable to discharge product taken from the bottom of the can. In the embodiment shown in FIG. 9, the shell 16 is carried downward as at 16a, to engage a cylindrical closure member 45, which has a channel 46 extending axially through it. The closure member has a downwardly extending neck 47 adapted to receive a hose or tube 48, here indicated in dot-and-dash lines, which will extend to the product at the bottom of the can. It is, of course, apparent that a similar construction could be readily incorporated in other embodiments, such as that illustrated in FIG. 2, if desired, and conversely, that the valve mechanism of FIG. 9 could be used without adding the means for connecting to a tube.

One of the advantages of the embodiment shown in FIG. 2, as compared to that illustrated in FIG. 7, is the ease with which the lower end of the stem can be formed to incorporate the resilient flanged tip 27, which will pass readily through the inner bore of the valve body, but will flare out after doing so to form a very tight seal against the mating surface 28 of the valve body 18. The provision ofa similar mechanism at the end of a metal tube, as shown in FIG. 7, however, requires that the flanged tip be separately handled and secured to the end of the tube. This involves an additional manufacturing operation, and consequent increase in cost.

It should be noted that assembly of the various components of this valve is facilitated by the provision of suitable shoulder bevels 32,32 at the pedestal top and at the lower end of the narrowed section 22, respectively. In both cases, these shoulder bevels facilitate movement of the stem through the sealing

washers

30 and 26, respectively. When the valve is being assembled, the stem 31 is depressed sufficiently to pass through the washer 30, and this causes the stem end 19' to pass below the lower rim of the valve body 18, whereupon the resilient flange 27 expands, thus holding the parts together until they are installed within the valve cup 15, as previously described.

It should, perhaps, be noted that the rib 17 is not formed until the valve is in its intended position. The valve body 18 is slightly enlarged, near its upper end, but it and its outer shell 16 are narrowed, slightly, a little farther down, to accommodate the rib or ridge 17 when it is crimped into the pedestal. Shaping the valve body in this way permits it to ride up against the resistance of the resilient material, as previously described, but prevents it from dropping out in the opposite direction.

The embodiment of this invention which is illustrated in FIG. 9 (with or without the addition of the bottom closure and neck to accommodate a tube or hose) is the easiest to make and the simplest to use, provided the intended use is one which does not require the extra safety of the double sealing washer arrangements of the other forms. The simplified form therefore deserves consideration under such conditions, since cost factors measured in mills become significant when the product itself may be manufactured in millions.

The plastic valve stems have been very carefully devised in order to permit them to be injection molded. The

upper structure

19,31 is calculated to afford max imum strength against lateral impact, so that the stem will not be broken if the can is dropped. The vertical, inwardly extending ribs 35 provide strength for the stem, and the solid central core with which they merge affords a good strong connection between upper and lower valve stem portions. The flat lands 37 leave ample cylindrical surface between them to perform the guiding function needed. In other words, although the injection-molded valve stem is much more intricate in form than the metal tube of FIG. 7, it is notably easier and less costly to produce in quantity.

In all forms of this invention, it is contemplated that the space which lies between the washer at the top of the valve housing 16 and the top of the valve body 18 will be filled with a resilient composition, having sufficient resistance to avoid upward movement of the valve body and opening of the ports 44 until the pressure within the aerosol can has increased significantly above its normal value. Although cellular material, such as cork, seems to be sufficiently effective, elastomeric material generally commends itself for use in this environment. Foamed latex, or sponge rubber, or foamed styrene or other plastic material, should be good substitutes for cork.

1 claim:

1. A valve for use in a can containing an aerosol under pressure, said valve being mounted in a pedestal in the valve cup of said can, said valve comprising a body having a bore extending axially therethrough, a spring-biased valve stem slidably mounted in said bore and ported to provide a fluid path, on downward movement for a predetermined distance, for the discharge of aerosol from the can; an annulus of resilient material within the pedestal above the upper face of the valve body, a resilient outwardly flaring closure element at the lower end of the valve stem adapted, when the stem is in its closed position, to engage the lower face of said valve body which is exposed to the interior of the can, said valve body being movable upwardly against the resilience of said spring and annulus, in response to abnormally high pressure, to expose said porting and allow aerosol to escape.

2. A valve as set forth in claim 1, in which the valve stem has a discharge passage therein in the lower portion of which a solid central core is provided, and axially extending ribs provide flow channels between said core and the inner wall of a portion of said bore.

3. A valve as set forth in claim 1, wherein the annulus of resilient material is organic in nature and cellular in form.

4. A valve as set forth in claim 3 wherein the annulus of resilient material is an expanded elastomer.

5. A valve as set forth in claim 3 wherein the annulus of resilient material is of cork.

6. A valve as defined in claim 1, wherein the lower face of the valve body and the mating upper face of the outwardly flaring closure element are inclined outwardly and upwardly from the foot of the valve stem.

7. The valve as defined in claim 1, wherein the valve stem is a rigid tube, ported near its lower end and having an outwardly flaring resilient closure element united to its lower end.

8. Valve mechanism for use in an aerosol can having a conventional valve cup and pedestal, said mechanism comprising a valve shell lining said pedestal, the inner surface of which shell defines a cylindrical bore, a valve body mounted within said bore, and having an axial passage therethrough which defines the surface of an intermediate bore; said valve body also having an inner channel therethrough defining an inner bore; a valve stem mounted axially of said valve body and having a portion of a diameter to fit slidably within said intermediate bore, said valve stem also having a lower extremity of a diameter to fit said inner bore, and spring means reacting between the larger diameter of said valve stem and the surface of said valve body where it is narrowed to rovide the inner bore.

9. Appara us as defined in claim 8, wherein relative movement can occur between the valve body and the valve shell.

10. A valve assembly for an aerosol container, comprising a valve stem and a valve body surrounding the stem, the stem projecting exteriorly of the container and having a discharge passage therein, the stem and body having valve parts at one end thereof providing for opening and closing of communication between the interior of the container and said discharge passage upon inward axial movement of the stem and also upon outward axial movement of the body, the communication being opened when the stem moves inwardly with respect to the body and closed when the stem moves outwardly with respect to the body, stop means limiting outward movement of the stem, the body being movable outwardly in the container with respect to the stop limited position of the stem and having its inner end exposed to the pressure in the container, yielding means urging the stem outwardly and the body inwardly of the container, and stop means limiting the inward movement of the body.

11. A valve assembly as set forth in claim 10, wherein a portion of the stern which extends beyond the upper surface of said body is surrounded by a mass of cellular material and a peripheral shell surrounds the said body and the said mass of material.

12. The valve assembly as set forth in claim 10, wherein the discharge passage is configured to communicate with the interior of the container by way of a plurality of peripheral passages in the lower portion of the stern.

13. For use in the valve assembly of an aerosol can, a valve stem having a discharge passage therethrough, said stem having a large diameter for a substantial portion of its length, a head end of lesser diameter extending axially from one face of said large diameter portion, an intermediate portion of reduced diameter extending axially from the opposite face of said large diameter portion, and a foot portion which terminates in a resilient flange that extends radially outward, the head end having a shoulder which is beveled inwardly towards the large diameter portion and an intermediate portion terminating in a shoulder which is beveled inwardly towards the foot portion; a coiled spring surrounding the intermediate portion, the foot end being adapted to pass the opening in a resilient washer and the head end being adapted to pass the opening in a resilient washer, whereby application of the washer elements positions and retains the stem and spring in assembled relationship.

14. A valve assembly as set forth in claim 13, wherein a valve body surrounds the valve stem and the spring, and is held in assembled relationship by the resilient washer first named and by the resilient flange at the termination of the foot.

15. A valve assembly as set forth in claim 14, wherein the valve body is slidably positioned within an outer shell which is configured to prevent movement of the body in the direction of the foot.

Claims

8. Valve mechanism for use in an aerosol can having a conventional valve cup and pedestal, said mechanism comprising a valve shell lining said pedestal, the inner surface of which shell defines a cylindrical bore, a valve body mounted within said bore, and having an axial passage therethrough which defines the surface of an intermediate bore; said valve boDy also having an inner channel therethrough defining an inner bore; a valve stem mounted axially of said valve body and having a portion of a diameter to fit slidably within said intermediate bore, said valve stem also having a lower extremity of a diameter to fit said inner bore, and spring means reacting between the larger diameter of said valve stem and the surface of said valve body where it is narrowed to provide the inner bore.

9. Apparatus as defined in claim 8, wherein relative movement can occur between the valve body and the valve shell.

11. A valve assembly as set forth in claim 10, wherein a portion of the stem which extends beyond the upper surface of said body is surrounded by a mass of cellular material and a peripheral shell surrounds the said body and the said mass of material.

12. The valve assembly as set forth in claim 10, wherein the discharge passage is configured to communicate with the interior of the container by way of a plurality of peripheral passages in the lower portion of the stem.