Patent Application
20080093396
For the purpose of illustrating the invention, the drawings show a form of the invention that is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and instrumentalities shown in the drawings.
Referring to the drawings, where like numerals identify like elements, there is illustrated in
The cap body 12 includes an outer skirt 34 depending downwardly from a top surface 36. The skirt 34 is designed to secure the container closure 10 to the top opening of a container 50 through any conventional attachment mechanism, such as threads or snap-on engagement. A snap-on attachment is illustrated in
The cap body 12 further includes a hollow generally cylindrical plug seal 20 depending downwardly from the top surface 36 to engage and seal against the inner wall 54 of the container neck 52. Two raised annular beads 30, 32, formed on the outer surface of the plug seal 20, are in intimate contact with the inner wall 54 of the container neck 52 when the closure 10 is installed onto the container 50. In a preferred embodiment, the lower bead 32 is slightly larger than the upper bead 30.
The plug seal 20 varies in thickness. The varying thickness is designed to provide stiffness where the top surface 36 attaches thereto while at the same time permitting independent movement of the upper and lower beads 30, 32. The plug seal 20 preferably comprises a tapered upper portion 22 that transitions into a substantially constant thickness lower portion 24 at a midpoint 26, the midpoint simultaneously defining the distal end of the upper portion 22 and the proximal end of the lower portion 24. Specifically, the upper portion 22 tapers along its inner wall from a relatively thicker proximal end, located at the junction of the plug seal 20 with the top surface 36, to a relatively thinner distal end, located at the midpoint 26 of the plug seal 20. The lower portion 24 has a substantially constant thickness equal to the thickness of the upper portion 22 at the distal end thereof, and continues from the midpoint 26 of the plug seal 20 to the distal terminus 28 thereof. The midpoint 26, where the tapered upper portion 22 preferably smoothly transitions into the thinner lower portion 24, is preferably located at or below the position of the upper bead 30 and need not be at the halfway point between the proximal and distal ends of the plug seal 20.
The varied thickness of the plug seal 20 provides multiple advantages. This is illustrated in
An additional advantage of the varied thickness of the plug seal 20 is that the thinner lower portion 24 of the plug seal 20 between the midpoint 26 and the distal terminus 28 (which coincides with some or all of the portion of the plug seal 20 between the beads 30, 32) reduces the force required to insert the plug seal 20 into the container neck 52. Further, the wide base of the tapered portion 22 improves the consistency of manufacture of the plug seal 20, providing a thicker lead-in and a more controlled mold flow area for injection molding than if the plug seal 20 were to be of a uniform thin cross-section. The thicker lead-in decreases the possibility of short shots, and in particular ensures consistent molding of the lower bead 32 and the lower portion 24 of the plug seal 20.
By way of non-limiting example, the description of a particular embodiment of the container closure will further elucidate the features of the present invention. In one embodiment, the plug seal 20 has a length equal to approximately one-third its outside diameter, the length being divided nearly equally by the midpoint 26 defining the upper portion 22 and the lower portion 24. The tapered upper portion 22 is about two times as thick at its proximal end as at the midpoint 26 of the plug seal, and more preferably is about 2.3 times. The outer wall of the plug seal preferably is substantially vertical, and the inner wall of the plug seal at the upper portion preferably tapers outwardly at an angle of approximately 10-20 degrees and more preferably at 14 degrees. The substantially constant-thickness lower portion 24 matches the thickness of the upper portion 22 at the midpoint 26 and preferably extends vertically downward from the midpoint 26 to the distal end 28 of the plug seal. The lower portion preferably has a thickness of about 0.019 inches. It should be readily apparent that the lower portion of the plug seal need not have a constant thickness.
The upper bead 30 is formed on the outer wall of the plug seal 20 preferably slightly above the midpoint 26, enlarging the outer diameter of the plug seal 20 by about 2.8%. The lower bead 32 is formed on the outer wall of the plug seal 20 preferably at or near the distal end 28 and is about 20% larger than the upper bead 30. The lower bead increases the outer diameter of the plug seal 20 by about 3.5%. The upper bead is preferably has a radius of about 0.040 inches an protrudes by about 0.009 inches from the outer wall of the plug seal. The lower bead preferably has a radius of about 0.040 inches and protrudes by about 0.011 inches from the outer wall of the plug seal
The combination of the upper and lower circumferential beads 30, 32 formed on the outer surface of the plug seal 20 provides a double seal system that has been shown in leak testing to be superior to what can be achieved with a single bead. Additionally, the double bead seal system of the present invention is superior to existing double and multiple bead seals because of the ability of the slightly larger lower bead 32 to flex and seat itself on the neck wall 54 independently from the slightly smaller upper bead 30, which combination provides a consistent seal despite small defects or non-uniformities that may be present along the inner surface of the neck wall 54.
It should be readily apparent that the cap can be used in a variety of orientations. As such, the reference in the application and claims to specific directions such as “upper” and “lower” are for purposes of identifying relative locations of the elements and are not intended to limit the claims to a specific orientation of the cap. For example, if the cap is inverted, the beads would obviously be above the “top” surface, and the thickness of the plug seal would taper (narrow) as the plug seal extends upward.
The foregoing describes the invention in terms of embodiments foreseen by the inventor for which an enabling description was available, notwithstanding that insubstantial modifications of the invention, not presently foreseen, may nonetheless represent equivalents thereto.
