Valve Stem Sealing Ring

Abstract

A sealing system for pressurized container valves particularly designed for the dispensing of solid products in powdered form including means for preventing the disabling buildup of the product residue on the sealing surfaces.

Description

BACKGROUND OF THE INVENTION

Aerosol dispensers commonly contain a supply of the product to be dispensed together with a quantity of propellant in liquid form, all held within a pressurized container. The valves in such devices are actuated by a movement of the valve body with respect to the pressurized container which movement uncovers an orifice completing a path from the container to a discharge nozzle. The product to be dispensed and the propellant are forced along the path by the pressure of the propellant within the container.

Because of their mutual solubility, liquid products tend to remain well mixed with the propellant during movement along the path. However, insoluble portions of some products and portions of particulate or powdered products tend to fall from the flowing stream of product and propellant and may accumulate at places along the path. This accumulation of undispensed product can cause disabling of the dispenser by clogging the orifice so that further discharge is diminished or by lodging on the sealing surfaces, preventing complete and proper sealing of the valve so that the propellant gas seeps out uncontrollably, prematurely exhausting the propellant supply. One proposed solution to the latter problem, applicable to aerosol valves of the type wherein sealing is accomplished by the abutting of a portion of the valve body against the underside of the sealing gasket, is proposed in British Patent No. 1,216,655. An apparently similar valve appears in Aerosol Age, Jan. 1, 1969, at page 24. It involves the use of three annular ribs concentric with each other and with the central axis of the valve and arranged to press upward against the bottom of the sealing gasket when the valve is in its closed position to establish a seal. During closure, accumulated particles of solid product are deflected laterally to occupy the grooves between the ribs, and since sealing is accomplished between the points of the ribs and the gasket, it is not at first affected by the presence of such particles. However, as more and more particles accumulate in the grooves, their net bulk may begin to adversely affect the effectiveness of the seal. The present invention provides a way of preventing seepage from pressurized aerosol containers which is less subject to loss of effectivness by product accumulation.

SUMMARY OF THE INVENTION

The present invention is particularly applicable to aerosol valves of the type wherein valve sealing is accomplished primarily by radial force exerted on the valve body by its encircling gasket. In previous constructions of this valve type, the valve body typically includes a narrow cylindrical section including the valve orifice and encircled by the gasket. A conical tapered section above the cylindrical section is topped by an upstanding valve stem. The orifice in the narrow cylindrical section communicates with a hollow interior passage in the valve body leading to the discharge orifice. The narrow cylindrical section and at least a portion of the conical tapered section are encircled by the aperture of an annular resilient gasket when the valve is closed, but when the valve body is depressed, the conical tapered section causes the inner aperture or sealing surface of the gasket to peel away from the valve body, thereby opening the dispensing path through the orifice.

According to the present invention a protruding annular ridge is provided about the narrow cylindrical section of the previously described valve body, and the valve orifice is located in a position above this ridge, in the upper region of the cylindrical section or in the conical tapered section of the valve body. The protruding ridge presses into the resilient gasket, providing a labyrinthine sealing contour less likely to leak than previous constructions. In addition, depression of the valve body for valve actuation results in some relative motion of the valve body with respect to the sealing surface of the gasket which moves the ridge with respect to the sealing gasket. This tends to dislodge accumulations of undispensed solid product. Further, during closure, flow is terminated before the gasket is restored to its radially compressed engagement with the valve body thereby providing an opportunity for disentrained particulate matter in the sealing region to fall away from that region.

DRAWINGS

FIG. 1 is an elevational view in partial section showing the valve of the present invention in the closed position, and

FIG. 2 is an elevational view in partial section showing the same valve during actuation, with the valve orifice shown rotated laterally 90.degree. from its position in FIG. 1.

DETAILED DESCRIPTION

Those Figures show a valve assembly 10 fitted and crimped into a pedestal portion 11 of a mounting cup closure for a pressurized dispenser, not shown. Valve assembly 10 includes dip tube 12, dip tube receiving nipple 13, valve housing 14, coil spring 15, and valve body 16. A resilient annular gasket 17 encircles a section of valve body 16. Valve body 16 includes an upstanding hollow valve stem 19, below that a conical tapered section 20 containing an orifice 21, then a narrowed cylindrical section 22 having an encircling protruding annular ridge 23, and finally a lower portion 24 adapted to receive a coil spring 15. Shoulder 25 is formed by the intersection of the narrow portion 22 and the lower portion 24 of valve body 16. When the valve is in its closed position, shown in FIG. 1, shoulder 25 abuts against the underside of gasket 17 under the urging of spring 15 to provide a sealing surface and the inner edge of gasket 17 presses tightly against the surfaces of valve body 16, including those of its encircling ridge 23, to provide the primary seal.

The valve is actuated by applying sufficient downward force on valve stem 19 to overcome the upward bias of spring 15. As valve body 16 moves down, tapered section 20 deflects downward the inner edge of gasket 17, causing it to peel away from orifice 21 and eventually expose the orifice 21 to the pressurized product within the container. During the initial phase of the opening operation, shoulder 25 will leave contact with the underside of gasket 17 and the inner edge of gasket 17 will be partially peeled away from valve body 16.

It will be apparent that the bottom of the inner edge peels away from the valve body first. Because, in the present invention, orifice 21 is located at a higher position on the valve body than in most valves of this type, the stroke required to depress the inner edge of gasket 17 enough to expose orifice 21 to the pressurized interior of the container is somewhat longer than is otherwise required. The significance of this longer stroke will become apparent from the following discussion.

During the opening operation valve body 16 simply moves downward, while points on the inner sealing surface of gasket 17 move both downward and radially away from the valve body and also undergo some compression. This deflection of the gasket results in motion of the inner sealing surface of the gasket with respect to the valve body 16 and its integral ridge 23. In other words, a given point on the gasket sealing surface moves downward a smaller distance during the opening operation than the adjacent point on valve body 16. Therefore, as ridge 23 moves downward, there will be relative vertical movement between the ridge and the surrounding inner sealing surface of gasket 17. This relative motion tends to dislodge product residues present on the valve body or the gasket sealing surfaces. If the product residue is in the form of agglomerations or clots, the ridge 23 will tend to pulverize the clots upon closure motion and tend to dislodge the clots from the sealing surface.

Furthermore, because the orifice 21 is not significantly unsealed until the valve body 16 has nearly completed its downward movement, particulate matter which has been dislodged by the interaction of the ridge and the inner gasket edge is free to fall back into the container. Thus the longer stroke required prior to opening and subsequent to terminating product flow on closing ensures that the dislodged material will have an opportunity to fall away and will not be swept up to other sealing surfaces or to the valve orifice.

While many ridge cross-sections are feasible for the practicing of the present invention, it has been found particularly efficacious to use a triangular ridge having a base thickness of 0.0034 inches and a height of 0.003 inches, mounted on a narrowed cylindrical portion (corresponding to portion 22) approximately 0.125 inches in diameter.

Claims

I claim:

1. A dispensing valve for a pressurized aerosol container comprising:

a valve housing,

a valve body movable axially with respect to the housing between closed and open positions, the valve body having a discharge passage communicating with the exterior of the container, and a valve orifice extending radially into communication with said discharge passage,

an annular resilient sealing gasket having a central aperture defined by a sealing surface encompassing and sealing said valve orifice when the valve body is in the closed position,

means to bias the valve body toward the closed position, and

an annular ridge means encircling said valve body located interiorly of the container from the valve orifice on a portion of the valve body encompassed and sealed by the resilient sealing means when the valve body is in the closed position with said ridge means engaging the sealing surface of said annular gasket.

2. The valve as described in claim 1, wherein the valve body includes an upstanding hollow stem portion including said discharge passage, a cylindrical portion of smaller diameter than the stem portion, and an interposed conical portion tapering from the stem portion to the cylindrical portion, the radial valve orifice being located in said conical portion and the ridge means being located on said cylindrical portion.

3. The valve as described in claim 2, wherein the ridge means comprises at least one circumferential projection on the valve body in a plane substantially prependicular to the axis of the valve body.

4. The valve as described in claim 3, wherein the cross section of the projection is a shape having a sharp apex.