BACKGROUND OF THE INVENTION
The present invention relates in general to tamper-evident structures
for container closures and caps. More specifically, the present invention relates
to a container closure assembly that includes a snap-on overcap. The overcap includes
a tamper-evident feature. The specific style of container closure for use with the
disclosed snap-on overcap, as described for the present invention, includes a bung
style plug that threads into an internally-threaded container opening. In one embodiment
of the present invention, the bung style plug includes a central portion arranged
with internal, modified buttress threads and the overcap includes a centrally-positioned
post that is constructed and arranged with a series of cooperating external, modified
buttress threads. These external threads are designed to engage and interlock with
the internal threads of the bung style plug for an axially-directed snap fit of
the overcap into and over the bung style plug. The requisite flexing of the external
threads for this snap-on assembly with the plug is enabled by the modified buttress
thread form and the plastic construction.
One of the improvements provided by the present invention is the ability
to provide a tamper-evident structure in combination with a bung style plug. Another
improvement provided by the present invention is found in the simplicity of the
overcap and the ease of assembly into and over the bung style plug.
SUMMARY OF THE INVENTION
An overcap for assembly to a container closure plug according to one
embodiment of the present invention comprises a top portion defining a pair of weakened
score lines partitioning the top portion into a center section and first and second
outer sections, a surrounding sidewall, a pair of oppositely-positioned flange sections
in unitary connection with the surrounding sidewall, one flange section being connected
by a portion of the sidewall to the first outer section and the other flange section
being connected by another portion of the sidewall to the second outer section,
a center post axially extending from the center section and being constructed and
arranged for assembly to the closure plug and tamper-evident means for providing
a visual indication of an attempt to remove the overcap from the closure plug.
One object of the present invention is to provide an improved container
closure assembly that includes a snap-on overcap.
Related objects and advantages of the present invention will be apparent
from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
DESCRIPTION OF THE PREFERRED EMBODIMENTS
- FIG. 1 is a top plan view of an overcap according to a typical embodiment of
the present invention.
- FIG. 2 is a front elevational view of the FIG. 1 overcap.
- FIG. 3 is a bottom plan view of the FIG. 1 overcap.
- FIG. 4 is an exploded view of the FIG. 1 overcap in combination with a closure
plug, sealing gasket, and container opening.
- FIG. 5 is a front elevational view, in full section, of the FIG. 1 overcap.
- FIG. 6 is a front elevation view, in full section, of the closure plug illustrated
in FIG. 4.
- FIG. 7 is a front elevational view, in full section, of the sealing gasket illustrated
in FIG. 4.
- FIG. 8 is a front elevational view, in full section, of the container opening
illustrated in FIG. 4.
For the purposes of promoting an understanding of the principles of
the invention, reference will now be made to the embodiments illustrated in the
drawings and specific language will be used to describe the same. It will nevertheless
be understood that no limitation of the scope of the invention is thereby intended,
such alterations and further modifications in the illustrated device, and such further
applications of the principles of the invention as illustrated therein being contemplated
as would normally occur to one skilled in the art to which the invention relates.
Referring to FIGS. 1-5, there is illustrated a snap-on overcap 20
that is molded out of plastic as a unitary member according to the present invention.
Overcap 20 includes a top panel 21, opposite radial flange sections 22 and 23, annular
sidewall 24, pins 25 and 26, and center post 27. Top panel 21 is partitioned into
three sections 30, 31, and 32 by a pair of V-shaped notches 33 and 34, or what could
also be described as weakened score lines. These weakened score lines 33 and 34
act like living hinges at the time of proper removal of overcap 20 from its cooperating
bung plug 37.
Partitioned section 31 is considered the center section of the three
with partitioned sections 30 and 32 being described as first and second outer sections.
As should be clear from the drawing illustrations, one flange section 22 is connected
by a portion of annular sidewall 24 to the first outer section 30. In a similar
or virtually identical manner, the other radial flange section 23 is connected by
another portion of annular sidewall 24 to the second outer section 32.
As will be described in the context of FIGS. 4, 6, 7 and 8, overcap
20 is constructed and arranged to snap into bung plug 37 and to extend over and
around the top portion 38 of bung plug 37. Top portion 38 includes an upper surface
39, wrench recess 40, radial lip 41, outer surface 42, and annular gasket-receiving
channel 43. Annular sidewall 24 in cooperation with top panel 21 defines a recessed
space 46 that is constructed and arranged to receive top portion 38 of bung plug
37. Since the bung plug 37 is received within the container (neck) opening 71, it
should be noted that recessed space 46 has a diameter size sufficient to also receive
raised wall 79. In order to achieve or create this overcap-bung plug assembly, it
is necessary for center post 27 to fit into the coaxially centered tubular opening
47. It is also necessary for the two pins 25 and 26 to fit into wrench recess 40.
The wrench recess 40 includes an inner cylindrical portion 48 opening into four
equally spaced, radial pockets 49. By positioning the two pins 25 and 26 approximately
180 degrees apart, one pin fits into one pocket 49 and the other pin fits into an
oppositely-disposed pocket 49.
Center post 27 is slightly tapered from top panel 21 to lower edge
51, though otherwise center post 27 is generally cylindrical in shape. The outer
annular wall 52 includes a series of external, modified buttress threads 53. Each
thread 53 has an angled surface as the leading edge 54 and a substantially flat
portion 55 as a trailing edge. In an upright orientation, this flat portion 55 of
each thread, or what can be called the pressure flange, is generally horizontal.
The horizontal direction is defined in terms of the axial centerline 56 being substantially
vertical. The leading and trailing edges are defined in terms of the direction of
pushing the overcap 20 downwardly onto the installed bung plug 37.
The tubular opening 47 is a blind opening due to lower wall 59. The
opening 47 includes two generally concentric sections 60 and 61. Section 60 is defined
by generally cylindrical wall 62 and includes a series of internal modified buttress
threads 63. Section 61 is defined by generally cylindrical wall 64. Walls 62 and
64 are substantially concentric to each other with wall 62 having a larger outside
diameter as compared to the outside diameter of wall 64. The resulting radial offset
between these two generally concentric sections 60 and 61 is defined by radial wall
As would generally be understood with snap-on, unidirectional designs,
there is a desire to have one direction of movement of one component permitted (relative
to the other component) and the reverse direction of movement prevented. In the
case of the present invention, the leading edge 54 of each external thread 53 has
a profile and material (plastic) that enables it to flex and ramp over each internal
thread 63 as the overcap 20 is pushed axially downwardly into and onto bung plug
37. This allows the overcap 20 to have a "snap-on" assembly to bung plug 37. Abutment
of top panel 21 against top portion 38 indicates a completed assembly of the overcap
20 onto the bung plug 37. While this might represent an axial position between sequential
points of external thread-to-internal thread engagement, it is not the function
of overcap 20 to create a sealed barrier against leakage. Rather, one function of
overcap 20 is to create a barrier to debris. Another function of overcap 20 is to
provide a tamper-evident feature.
Referring to FIGS. 3 and 5, it will be seen that center post 27 includes
an equally-spaced series of eight radial ribs 66 positioned around the inside diameter
surface 67. These ribs 66 provide additional strength and rigidity to center post
27, particularly during the snap-fit installation of overcap 20 onto bung plug 37.
The desired external thread (overcap 20) and internal thread (bung
plug 37) engagement functions to retain the overcap 20 on bung plug 37. When it
is intended to remove overcap 20 in order to have access to the container contents
by the removal of bung plug 37, there is a specific procedure to be followed. This
procedure creates an altered appearance to the overcap 20 and is described in greater
detail hereinafter. Since tampering attempts might be made to try and remove overcap
20 without visually revealing that this has been done, it is important to include
a tamper-evident feature as part of the present invention. The described external
thread 53 engagement with the internal threads 63 on the bung plug is an important
structural element of the tamper-evident capability of the present invention.
Any attempt to pull upwardly on the snap-on overcap 20, so as to try
and remove it from the bung plug 37, is prevented by the blocking, abutting engagement
of the flat (horizontal) portion 55 of each external thread 53 against the internal
threads 63. This is typical of any proper threaded engagement where one component
cannot be pulled free of the other due to the mating of the threads. Each portion
55 is shaped with a horizontal surface such that the external threads 53 are not
able to bend or deflect a sufficient amount to enable these threads to clear their
immediately adjacent (axially upward) internal thread 63. This external thread-to-internal
thread interlock (mating) keeps the overcap 20 in position on bung plug 37 until
it is desired to be removed, presumably by an authorized end user.
One aspect of the tamper-evident construction of overcap 20 is directed
to the unitary fabrication of overcap 20, including the unitary combination of pins
25 and 26. Importantly, each pin 25 and 26 is joined to top panel 21 by a circular
interface 68 (see FIGS. 1 and 3) that includes four, spaced-apart web sections 69,
that are weakened due to their web structure, i.e., thinner material. As will be
described in greater detail hereinafter, a tampering attempt, i.e., trying to remove
the overcap 20 in some way other than the intended manner, causes the pins 25 and/or
26 to flex in such a way that they try to pull away from top panel 21. The stress
that occurs due to the bending results in breaking open one or more of the web sections
69. The broken web section or opening that is left is an immediate visual indication
that a tampering attempt has been made. This allows the authorized end user to inspect
the container and the container contents to determine whether that tampering attempt
Referring to FIGS. 6, 7, and 8, the cooperating components with overcap
20 that complete the disclosed closure assembly according to the present invention
are illustrated. Much of bung plug 37 has already been described. Additionally though
it will be seen that the sidewall 70 is externally-threaded. Bung plug 37 is a unitary,
molded plastic component. The outlet portion 71 of the cooperating container 72
is illustrated in FIG. 8. This outlet portion 71 (i.e., neck opening) is internally-threaded
and is constructed and arranged for the tight and secure threaded receipt of bung
plug 37. The square cut annular gasket 73 (see FIG. 7) is constructed and arranged
to sealingly fit within channel 43, with a portion axially extending for compression
against the inset radial shelf 78 of neck opening 71. Shelf 78 is concentrically
surrounded by cylindrical, raised wall 79 of neck opening 71. As the bung plug 37
is threadedly advanced into the neck opening 71, the gasket that fits within channel
43 of bung plug 37 is advanced into engagement against radial shelf 78. Continued
advancement causes the elastomeric gasket 73 to be compressed, thereby establishing
a liquid-tight seal between bung plug 37 and container 72. The full threaded advancement
of bung plug 37 into neck opening 71 positions the radial lip 41 of the bung plug
37 radially inside of raised wall 79. The outer surface 42 is in close proximity
to the inner surface 80 of the raised wall 79. The upper surface 39 is substantially
flush with the upper surface 81 of raised wall 79. An exploded view of the assembly
of the container neck opening 71, gasket 73, and bung plug 37 including overcap
20 is illustrated in FIG. 4. Overcap 20 fits over and around raised wall 79 when
fully snapped on to and into bung plug 37.
The top panel 21 of overcap 20 includes a raised portion 84 that is
generally centrally positioned on top panel 21 and importantly extends across or
spans both V-shaped notches, described as score lines 33 and 34. While a block letter
R has been used to represent this raised portion, it is to be understood that virtually
any letter, logo, shape or design can be used. The important design features for
this raised portion 84 include its relatively thin structure and a size sufficient
to extend across or span both of the score lines 33 and 34. The use of a letter
for raised portion 84 enables the manufacturer of the overcap, or of the overall
assembly, to be able to brand the product with a source of origin indicator.
Consistent with the disclosed invention, the overcap 20 is constructed
and arranged to snap over and onto bung plug 37, and over and around the raised
wall 79, or over and onto a similarly styled bung plug. Assembly of the overcap
20 is achieved by axially pushing center post 27 into tubular opening 47. This achieves
the intended external thread-to-internal thread engagement. In order to open the
disclosed assembly (see FIG. 4), the user begins by lifting up on both radial flange
sections 22 and 23. Since each score line 33 and 34 extends completely across the
top panel, four peripheral notches 85a-85d are created in the surrounding sidewall
24. The score lines 33 and 34, in cooperation with the peripheral notches 85a-85d,
allow the radial flange sections 22 and 23 to bend or hinge upwardly and inwardly
toward each other. As previously described, the thinner material for score lines
33 and 34 enables these two lines to serve as living hinges, helping to facilitate
the upwardly and inwardly bending or hinging of radial flange sections 22 and 23.
As a result of this upwardly and inwardly hinging, the two radial flange sections
22 and 23 create a pair of cooperating panels that the user can grasp in order to
twist off (i.e., unscrew) the overcap 20 and remove it from bung plug 37. As previously
described, there are external threads 53 on the overcap 20 of a modified buttress
form and cooperating internal modified buttress threads 63 in section 60 of the
bung plug 37. This means that a twisting action applied to overcap 20, using the
two radial flange sections 22 and 23, simply unscrews the external threads 53 from
the internal threads 63, allowing overcap 20 to be removed from bung plug 37 in
the intended manner. Removal of overcap 20 exposes the bung plug 37 so that it can
be removed (unscrewed) from the container 72 neck opening 71.
When the two radial flange sections 22 and 23 are hinged upwardly
and inwardly, using the two score lines 33 and 34 as living hinges, there is some
bending or flexing of raised portion 84 at each location where it extends across
score lines 33 and 34. Due to the material selected for overcap 20 and due to the
thicker material represented by raised portion 84 as compared to the material thickness
of score lines 33 and 34, the bending stress in raised portion 84 creates stress
discoloration or what is described as "whiting". While this is not of concern to
the authorized user who intends to remove overcap 20, this stress discoloration
and the use of raised portion 84 does provide a visual indication to the authorized
user if there has been a previous tampering attempt. If the authorized user sees
the stress discoloration in the raised portion, that would be an indication that
an attempt has been made and puts the authorized user on notice to inspect the container
and container contents to see if that tampering attempt has been successful. With
regard to this tamper-evident feature, it is important to note that the raised portion
84 is not notched or scored in any manner and thus at those lines of overlap where
it extends across the score lines 33 and 34, the bending action of the radial flange
sections 22 and 23 creates a stress line, resulting in the described stress discoloration.
Since it might be possible for an unauthorized user to remove overcap 20 by only
bending up on one of the two radial flange sections, it is appropriate to have the
raised portion extend across both score lines 33 and 34. However, if an alternative
design for overcap 20 is created where there is only one score line and only one
radial flange section, then the raised portion would only need to extend across
that one score line in order to provide the tamper-evident feature.
If there is an attempt to remove the overcap 20 in some other manner,
i.e., without using the radial flange sections 22 and 23 to twist off overcap 20,
the two pins 25 and 26 come into play as other tamper-indicating structures. An
axial direction of removal for overcap 20 does not affect pins 25 and 26. However,
if overcap 20 is not removed in the intended manner, pins 25 and 26, either one
or both, must flex relative to top panel 21 and this in turn causes one or more
holes in web sections 69, thereby providing a visual indication of a tampering attempt
or at least an indication of an improper opening attempt.
While the invention has been illustrated and described in detail in
the drawings and foregoing description, the same is to be considered as illustrative
and not restrictive in character, it being understood that only the preferred embodiment
has been shown and described and that all changes and modifications that come within
the spirit of the invention are desired to be protected.