US3269616A - Valve stem and buton structure for dispensing aerosol formulations - Google Patents

Description

Aug. 30, 1966 R. D. WEST 3,269,616

VALVE STEM AND BUTTON STRUCTURE FOR DISPENSING AEROSOL FORMULATIONS Filed Dec. 24, 1964 INVENTOR.

ROBERT u-wEsT A 7'TORNE V United States Patent 3,269,616 VALVE STEM AND BUTTON STRUCTURE FOR DISPENSING AEROSQL FORMULATIONS Robert D. West, Charlotte, N.C., assignor to Union Carbide Corporation, a corporation of New York Filed Dec. 24, 1964, Ser. No. 421,051 3 Claims. (6]. 222394) The present invention relates to aerosol containers and their associated valves and dispensing componentry and more particularly to a novel aerosol dispensing valve structure having interior passage characteristics particularly designed to obviate clogging due to the agglomeration of contents to be dispensed.

Pressurized aerosol containers are currently used to package and dispense a wide variety of fluids and fluidized solids materials. The valves included in these containers, as well as related operating parts interior of such containers, must be reliable, safe and, due to the disposable nature of such containers, should be easily manufactured and low in cost. In the most common type aerosol dispenser, the container is a hollow cylindrical can, tightly closed at one end, with the assembly comprising the dispensing valve mechanism arranged to form the other end of the container. For convenience in making this disclosure, one end will hereinafter be called the top or upper end and the other will be called the bottom or lower end of the container, although it is to be understood that these containers can be employed in any position through the well-known provision of a dip tube connecting from the valve structure down into the interior of the container. An annular shaped mounting cup, usually a metal stamping with an outer edge tightly crimped over the top end of the pressure container, forms the valve mechanism support and defines a top for the can. A vertically positioned hollow cylindrical valve chamber with an open top and a closed bottom is crimped, swaged or otherwise affixed to the axial center of said mounting cup on the underside to support and guide the moving parts of the valve. Between the upper circular rim of said valve chamber and the underside of the mounting cup forming the top of the container, an annular sealing gasket of rubber, flexible plastic material or the like having a centrally located circular opening therethrough is held in a fixed position by a subtending washer. In some valve embodiments, the inner edge of the sealing gasket is radially cantilevered over the edge of the hole in the washer to permit depression of the central part of the sealing gasket when the valve stem is depressed or pushed into the can. In other embodiments the washer hole and the central opening in the gasket are of substantially equal diameter and the valve stem, when depressed, moves slideably through the sealing surface defined by the gasket without any substantial depression thereof. The moving parts of a conventional valve comprise a vertically disposed cylindrical stem having a solid lower portion and a hollow upper interior defined by a longitudinally extending axial bore from its upper end. The stem is provided with at least one lateral orifice con necting the hollow interior with the stem exterior surface to form a valve stem inlet port. The typical arrangement is such that the cross-sectional area of the valve stem hollow interior is considerably greater than the cross-sectional area of the inlet port. Beneath the inlet port, usually on the completely solid portion of the stem, an increased diameter stem portion or shoulder is provided to engage the under side of the sealing gasket holding washer and prevent withdrawal of the stem from the container. A coil spring is arranged around the lower portion of the stem which, as noted above, is usually solid. The spring exerts expansive force between the 3,269,616 Patented August 30, 1966 "ice underside of the shoulder and the closed bottom of the hollow cylindrical valve chamber, maintaining the stem in such a postion that the valve stem inlet port is either outside of the container or sealably engaged with the sealing gasket. A dispensing button or cap is fitted atop the valve stem and contains an interior passage, usually having a right angle, connecting the valve stem hollow in terior with an outlet nozzle in the cap. The dispensing but-ton or cap is conveniently serrated on top to provide for finger tip grip contact in operation. One or more ports through the bottom of the cylindrical valve chamber provide access to the container interior or, if one is used, a dip tube extending into the interior of the container.

An aerosol dispenser of this general type is operated by exerting downward pressure .on the valve stem with a finger on the cap or button. The downward movement of the stem causes the stern inlet port to enter the pressurized interior of the container inside the valve chamber and aerosol contents flow from the container interior, up through a dip tube if there is one, through the ports at the bottom of the valve chamber and into the valve chamber, through the valve stem inlet port, the stem hollow interior, the passage in the operating cap and out through the outlet nozzle in the cap. The downward movement of the valve stem compresses the coil spring between the stem shoulder and the bottom of the valve chamber, providing a stored resilient force to urge the valve stem outward and cut oil the flow of the contents when finger pressure is released.

The contents of an aerosol container consists of the material to be dispensed, most conveniently referred to as use contents, mixed with a low boiling point liquid propellent composition which, upon expansion, carries the use contents outwardly of the can for deposit where de' sired. The ptopellent composition volatilizes into a harmless gas in the course of the dispensing action. As used herein, the term use contents is intended to mean that portion of the aerosol formulation which is ultimately desposited exterior of the container.

When valve structures which are conventionally available have been used to dispense powder, wax, or gel aerosol formulations, clogging frequently develops. Clogging is found to occur in zones of increased cross-sectional area adjacent zones or orifices of relatively lesser crosssectional area, for instance in the button or cap portion of the aerosol valve, most frequently around the exit orifice through which the dispensed material passes as a fine spray or in the hollow interior portion of the stem which usually has a considerably larger cross-sectional area than the stem inlet port. This has been found to be particularly true when slow spray rate design predicates greater than usual reductions in the valve stem and button orifices. It is known that the elfective dispensing of powder, wax and gel formulations, without clogging caused by agglomerations, is best accomplished by keeping the powder (wax or gel) to liquid propellant ratio constant throughout the valve assembly. While the benefits of the present invention apply equally to wax, gel and powder use contents, powder will be discussed for clarity of presentation. The maintenance of a constant ratio of powder to propellant enables the propellant most effectively to lubricate the powder in its passage through the valve assembly and prevent the deposition of agglomerative deposits of dry powder which can and frequently do clog the valve stem or button passages. Conventional designs of aerosol valves however involve valve stem and button assemblies which have, in effect, expansion chambers in which the ratio of powder to propellant changes drastically. Wherever, for example, a valve stem inlet port admits into a valve stem hollow interior of considerably larger cross-sectional area, the increased volume of the valve stem interior permits rapid expansion of the propellant liquid and its volatilization or flash-01f as a non powder-bearing gas up .through the button passages and out of the container. Unlubricated powder left in the stern passage then builds up in continued operation of the valve and causes stoppages in the button or cap passages, particularly at the discharge orifice.

With this then being the state of the art, the present invention was conceived towards the maintenance of a constant powder to propellant ratio throughout the entire exit path of the formulation being dispensed from an aerosol container. While the invention is uniquely suitable in overcoming the present day problems attending powder aerosol dispensing, it is similarly useful in dispensing any aerosol formulations where the useful component, i.e. the effective or use content, is vulnerable to clogging or agglomeration. Thus, materials such as waxes and gels and the like, as well as powder, can be more eifectively dispensed with the apparatus and method of the present invention.

Accordingly, it is an object of the present invention to provide a novel aerosol dispensing valve structure which is capable of continuously discharging aerosol formulation contents while maintaining constant the ratio of use material to propellant material in the formulation.

It is a further object of the present invention to provide for the effective discharge of aerosol packaged materials which are vulnerable to agglomeration and clogging without the useless loss of propellant composition.

It is a still further object of the present invention to provide for the full and complete discharge of aerosol packaged materials which are vulnerable to agglomeration and clogging and which would, with conventional valve assemblies, remain in part in the aerosol container after the complete expenditure of the aerosol propellant composition due to repeated flash-oft of the propellant composition by itself.

In general, the present invention comprehends an aerosol discharge arrangement wherein the several sequential cross-sectional areas of passages through which the formulation to be dispensed must pass decrease toward the final outlet nozzle or orifice in the stem button or cap. In other words, the dispensed materials leave the interior of the container and pass through a series of decreasing cross-sectional area zones, thereby effectively maintaining a substantially constant ratio between the use composition and the propellant composition comprised in the aerosol formulation.

The invention will now be described with greater particularity and with reference to the appended drawings wherein:

FIGURE 1 is a partially sectional view of the upper portion of an aerosol container showing a valve structure according to the present invention; 7

FIGURE 2 is a volumetric diagram showing qualitatively the relative size of sequential volumes through which aerosol packaged materials pass according to the present invention and FIGURE 3 is a diagram similar to FIGURE 2 but showing relative volumes of a typical conventional aerosol system.

In the embodiment of the drawings, pressure container 11 is closed at its top end by a mounting cup 13, of metal, plastic, or the like, having a centrally located circular opening therethrough. The cup 13 is tightly fitted to the container 11 by a rolled and crimped outer edge in a conventional manner. A hollow cylindrical valve chamber 15, having an open top and a bottom enclosure is pressfitted or swaged into a centrally disposed circular upwardly extending portion of mounting cup 13. The bottom of valve chamber 15 is provided with a multiplicity of ports 16 extending through said bottom to provide for the passage of container contents into the valve chamber either from a dip tube, if one is used, or from the con tainer interior. An annular valve seal 17 of rubber, plastic or the like, having a centrally located circular opening therethrough is arranged in the upwardly extending portion of mounting cup 13 and is supported on its underside by a valve seal retainer 19 which is in the form of a metal or the like washer also provided with a centrally located circular opening. Valve seal 17 and valve seal retainer 19 are held fixedly between the mounting cup underside and the upper rim of valve chamber 15 with the respective openings in the mounting cup, the valve seal and the valve seal retainer in registering alignment.

The valve movable components comprise a vertically disposed cylindrical valve stem 21, reciprocally movable through the openings in the mounting cup, valve seal and valve seal retainer. Valve stem 21 is provided with a longitudinal passage 25 extending from the valve stem upper end to a point of intersection with a valve stem transverse passage 23. Transverse passage 23 and longitudinal passage 25, as well as the point or zone of intersection between these passages, are, in accordance'with the present invention, of either exactly equal cross-sectional area or at least in a relationship such that the crosssectional area of the longitudinal passage 25 is no greater than the cross-sectional area of the transverse passage 23. A raised diameter portion or shoulder 22 is provided on a portion of the valve stem 21 below the valve seal retainer. A valve stem spring 27, lightly loaded in compression, is disposed around the lower portion of the valve stem and extends between the bottom of valve chamber 15 and the underside of stem shoulder 22 to maintain the upper surface of shoulder 22 in contact with the underside of the valve seal retainer 19. For convenience in assembly the valve stem shoulder 22 may be provided with an underside recess to securely seat the upper end of the spring 27. A valve dispensing head 29 is fitted atop the valve stem 21 and contains a longitudinally extending passage 31 and a transverse passage 33 ending in an exit flare. Passage 33 is actually equivalent to a conventional discharge orifice and beyond said passage the propellant composition is naturally free to completely volatilize. It is not critical to this invention therefore whether passage 33 is larger than contiguous passage 31 as long as it does not end in a reduced cross-sectional area orifice. In other words, when a discharge orifice is involved, it is necessary that passage 33 adjacent such orifice have a cross-sectional area equal to or smaller than but in no case larger than the cross-sectional area of passage 31. Preferably, however, the dispensing head passages 31 and 33 as well as their junction point or zone are of the same cross-sectional area to insure good lubrication of the use contents by the propellant composition for as long as possible in the discharge route. Further in accordance with the present invention, the cross-sectional area of dispensing head passage 31 must be equal to or less than the cross-sectional area of the longitudinal valve stem passage 25. The cross sectional area at the dispensing opening beyond dispensing head passage 33 may be of any desired cross-sectional area since, at this point, the contents being discharged from the container are considered fully emitted. A hollow dip tube 35 may be fitted over the lower portion of valve chamber 15 to extend downwardly into the container 11 and assure full feeding of the container contents to the dispensing valve assembly.

Referring now to FIGURES 2 and 3 of the drawings the principle upon which the present invention is predicated may be illustrated.

FIGURE 2 illustrates schematically the relative order of decreasing cross-sectional areas of the several sequential zones through which the use contents and the propellant composition pass in combination on their route out of the container. The respective portions of FIGURES 2 and 3 designated A represents the cross-sectional area of the container itself, the portion of the figure designated B represents the cross-sectional area of the dip tube. The portion of the diagram designated C represents the crosssectional area available for flow through the valve chamber 15. The portion of the section designated D represents the cross-sectional area of the valve stem transverse passage 23. The portion of the diagram in FIGURE 2 designated E represents the cross-sectional area of the longitudinally extending passage in the valve stem 21. The portion of the figure designated F represents the relative cross-sectional area of the longitudinally extending passage 31 in valve dispensing head 29 and the last portion of the figure designated G indicates the relative crosssectional area of the transverse passage 33 in dispensing head 29. A comparison between FIGURES 2 and 3 clearly shows that with conventional apparatus represented by FIGURE 3 at least one portion of the outgoing flow path involves entry of the mixture being dispensed into a zone of increased cross-sectional area, ie, the E zone, wherein a disproportionate expansion of the propellant fluid occurs, producing a phenomenon known in the art as flash-off. Such occurences tend to leave deposits of the use material in such zones. It can be seen from the illustration that in conventional aerosol valve structures where the cross-sectional area (E) of the valve stem longitudinal passage is greater than the cross-sectional area (D) of the stem transverse passage, the stem longitudinal interior passage constitutes a flashoff zone. This is so because normally the valve stem hollow interior is defined by a relatively thin stem wall and the lateral passage into the stem interior is an inlet port or orifice through the stem wall and of considerably smaller cross-sectional area than the stem hollow interior. The diagram of FIGURE 3 is merely illustrative of a typical situation encountered with known valve structures and it is to be understood that the increased cross-sectional area flash-off zone discussed hereinabove may occur at a different location in the discharge progression than in the valve stem longitudinal passage and may, in fact, occur at more than one point in the discharge flow path. Another zone in which flash off may occur is in the cap or button in cases where a relatively large cross-sectional area (G) passage lies between a discharge orifice and an (F) passage each of smaller cross-sectional area.

FIGURE 2 therefore illustrates clearly the criteria of design upon which the present invention depends. The essential feature then is the avoidance in the discharge flow path of any increased cross-sectional area followed immediately by a diminished cross-sectional area through which flow must pass, because it is only in these increased cross-sectional area zones Where the undesirable flash-off occurs, leaving deposits of the use material which build up in continual operations and ultimately cause malfunctioning and complete failure of the aerosol container dispensing system. The flow may thus progress through any number of zones having at least equal cross-sectional areas or through any number of sequential zones having respectively decreasing cross-sectional areas.

It is to be realized that the valve structures discussed in detail in this disclosure are considered only illustrative, since the principles and spirit of the present invention may be advantageously applied to other valve structures for continuous dispensing or even metered dispensing. The beneficial features of the present invention are considered applicable to virtually any aerosol dispensing valve whenever the problem solved by this improvement is encountered, the only essential requirement being strucural details such as will permit the decreasing or equal cross-sectional area progression in the outward flow path. The foregoing disclosure therefore should be considered as illustrative only and not construed in any limiting sense, it being intended to limit the invention only in accordance with the appended claims.

What is claimed is:

1. An aerosol formulation dispensing valve structure comprising, in combination, a valve chamber interior of an aerosol container, a valve stem having an interior passage selecta'bly connectable with the interior of said aerosol container, and a valve dispensing head having an interior passage connecting in flow relationship with said valve stem interior passage and a discharge nozzle in said valve dispensing head, said valve chamber, said valve stem interior passage and said valve dispensing head interior passage and discharge nozzle being comprised in a flow path for outward flow of aerosol formulation, each respective cross-sectional area available for outward flow of aerosol formulation through said valve chamber, said valve stem interior passage and said valve dispensing head interior passage being at the most equal to the cross-sectional area of that portion of the flow path immediately preceding.

2. In combination with an aerosol container charged with an aerosol formulation consisting essentially of a propellant composition and a use composition, an improved aerosol valve structure comprising, in combination, a valve chamber, a valve stem having an interior passage, and a valve dispensing head having an interior passage and a discharge nozzle, said valve chamber, said valve stem interior passage and said valve dispensing head interior passage and discharge nozzle being comprised in a flow path for outward flow of aerosol formulation from said container, each respective cross-sectional area available for outward flow of said aerosol formulation through said valve chamber, said valve stem interior passage and said valve dispensing head interior passage being at the most equal to the cross-sectional area of that portion 'of the flow path immediately contiguously preceding thereto.

3. In an aerosol dispensing valve structure wherein interior passages in a valve chamber, a valve stem and a valve dispensing head are comprised in a flow path through which an aerosol formulation passes outward from an aerosol container interior to a dispensing nozzle in said valve dispensing head, the improvement consisting of the total flow path having respective incremental cross-sectional areas along the outward fiow direction such that any single cross-sectional area available for flow of aerosol formulation therethrough is at the most equal to the immediately preceding incremental cross-sectional area.

References Cited by the Examiner UNITED STATES PATENTS 3,121,517 2/1964 Geary et al 222-394 M. HENSON WOOD, JR., Primary Examiner.

H. S. LANE, Assistant Examiner.

Claims (1)

1. 3. IN AN AEROSOL DISPENSING VALVE STRUCTURE WHEREIN INTERIOR PASSAGES IN A VALVE CHAMBER, A VALVE STEM AND A VALVE DISPENSING HEAD ARE COMPRISED IN A FLOW PATH THROUGH WHICH AN AEROSOL FORMULATION PASSES OUTWARD FROM AN AEROSOL CONTAINER INTERIOR TO A DISPENSING NOZZLE IN SAID VALVE DISPENSING HEAD, THE IMPROVEMENT CONSISTING OF THE TOTAL FLOW PATH HAVING RESPECTIVE INCREMENTAL CROSS-SECTIONAL AREAS ALONG THE OUTWARD FLOW DIRECTION SUCH THAT ANY SINGLE CROSS-SECTIONAL AREA AVAILABLE FOR FLOW OF AEROSOL FORMULATION THERETHROUGH IS AT THE MOST EQUAL TO THE IMMEDIATELY PRECEDING INCREMENTAL CROSS-SECTIONAL AREA.

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