Lockable closure for containers

A lockable closure for a container having an annular lip advantageously has locking means whereby the closure can be releasably locked to the container. The closure has at least an annular portion adapted to be disposed in contact with a portion of the annular lip of the container, and preferably also an annular wall adapted to contact a portion of a wall of the container to provide a sealing engagement therewith. The locking means generally comprises shoulder means for lockingly engaging the annular lip of the container and bending means adjacent the shoulder means for deflecting the shoulder means about the annular lip of the container. The closure is useful with containers formed of various materials, for example, of both metal and molded plastic.

FIELD OF THE INVENTION 
This invention relates to a closure for a container, and, more 
particularly, to a lockable closure, for example, a lid, which is 
releasably locked to a container having an annular lip. 
BACKGROUND OF THE INVENTION 
Container and closure combinations presently known to the art generally 
consist of injected molded containers and lids wherein one or more lips or 
edges are molded into one component while mating grooves are molded into 
the other component. Locking of the closure to the container is commonly 
provided by diametral sizing so that the marginal edge of the lid must be 
stretched during engagement and the components snap into locked position. 
In the common arrangement, the one or more lips or edges and mating 
grooves require a negative draft in at least one set of molds and 
therefore necessitates longer chill times in the molding operation so that 
the material can be deformed while withdrawing the component from the 
mold. The degree of negative draft required is directly related to the 
holding power of the closure, that is, the higher the degree of negative 
draft and the difficulty in removing the component from the mold, the 
greater the security of the locking arrangement. Further, the more secure 
the locking arrangement the more difficult it will be for a user to remove 
the closure from the container. The difficulty in removing the closure is 
often objectionable for applications where ease of removal of the closure 
without the use of tools, is desirable. 
In the case of containers for paint and similar substances, cylindrical 
metal cans have been the industry standard. While closures for these cans 
have been successfully designed, and the combination of can and closure or 
lid passes various tests, particularly the shipping drop test, the use of 
metal cans are objectionable both because of relatively expensive 
materials used therein and the inability to conveniently nest empty 
containers for economical shipping and storage. Attempts have been made to 
utilize molded plastic containers for paint and similar substances, but 
closures designed for such containers generally do not provide for 
positive locking of the closure to the container, and specifically, the 
combination of closure and container does not pass the test requirements, 
particularly the shipping drop test. 
Therefore, one object of the present invention is to provide a lockable 
closure for a container in which the closure can be brought into and out 
of locking engagement with the container. 
Another object of the present invention is to provide a closure which is 
applicable to containers of various materials and construction which can 
be brought into and out of locking engagement with the container. 
A further object of the invention is to provide a closure of simplified 
design producible by conventional molding methods with little or no 
negative draft, and which provides for locking of the closure to the 
container without supplemental locking means. 
Still another object of the present invention is to provide a closure 
having means for sealing and locking the closure which are relatively 
independent of the material or construction of the container. 
A further object of the invention is to provide a lockable closure having 
self-retaining locking means which retains its unlocked or locked 
condition, and can be conveniently locked and unlocked by the user. 
These and other objects and advantages of the present invention will be 
readily apparent to those skilled in the art from the following 
description. 
SUMMARY OF THE INVENTION 
In general, the objects and purposes of the invention are met by providing 
a closure having at least an annular portion adapted to be disposed in 
contact with a portion of an annular lip of a container, with the closure 
having shoulder means for lockingly engaging the annular lip of the 
container. The shoulder means of the closure extends from the annular 
portion of the closure, and in one embodiment comprises individual 
shoulders extending from the annular portion of the closure, and in 
another embodiment preferably comprises an annular shoulder again 
extending from the annular portion of the closure. The closure further 
includes deflectable bending means adjacent the shoulder means for 
deflecting the shoulder means about the annular lip of the container. In 
one embodiment the bending means is an annular wall extending from the 
shoulder means which may be of uniform thickness, and further may 
terminate in an annular portion of increased thickness with respect to the 
thickness of the remainder of the wall. In another embodiment, the bending 
means comprises a plurality of spokes or ribs extending from the shoulder 
means, whereby upon the deflection of the ribs the shoulder means adjacent 
thereto is pivoted about the annular lip of the container into and out of 
locking engagement with the lip of the container. The plurality of ribs in 
the last-described embodiment may integrally terminate in an annular ring 
of increased thickness with respect to the ribs to facilitate deflection 
of the ribs, and hence, the pivoting of the shoulder means about the 
annular lip of the container into and out of engagement therewith. 
The closure of the present invention preferably includes an annular wall 
positioned inwardly of the annular portion previously described with the 
annular wall having at least one portion which is adapted to contact a 
portion of a wall of the container to provide a sealing engagement with 
the container wall. The closure of the present invention preferably also 
includes an annular portion of less strength than the portion adapted to 
be disposed in contact with the annular lip of the container, with the 
annular portion of less strength being positioned adjacent the shoulder 
means, whereby upon deflection of the bending means, the shoulder means 
pivots about the portion of less strength into and out of locking 
engagement with the annular lip of the container. 
The lockable closure of the present invention can be utilized with 
containers manufactured of various materials and construction, for example 
metal cans, plastic containers, and the like. The container must have an 
annular lip about the opening to be closed by the closure of the present 
invention, but otherwise the shape and construction of the container is 
not of concern to the present invention. Preferably the container includes 
a tapered annular wall adjacent the annular lip against which a wall of 
the closure may be placed in sealing contact. The closure of the present 
invention is particularly useful with plastic containers, for example, 
plastic paint pails having an annular lip. 
The lockable closure of the present invention is preferably manufactured of 
resilient material to form a pliable closure, which may also be referred 
to as a lid. More preferably the closure is prepared by injection molding 
of a pliable plastic material, such as polypropylene or polyethylene or 
similar plastic materials and mixtures of such materials. Closures of the 
present invention constructed of the described materials are relatively 
pliable and can be placed over and/or into the opening of the container 
with a portion of the closure in contact with the lip of the container. In 
such position, the bending means of the closure is generally upturned and 
at zero stress. Upon applying a downward force to the bending means, the 
bending means will be deflected downwardly and outwardly causing the 
shoulder means positioned beneath the bending means to pivot about and 
into locking engagement with the annular lip of the container. As the 
deflecting force is applied to the bending means, the bending means and 
adjacent shoulder means of the closure are placed under stress and are 
forced toward the annular lip of the container. The continuation of the 
application of the deflecting force to the bending means causes the 
bending means to assume a downwardly position where the bending means is 
no longer under stress and the locking condition of the shoulder means to 
the annular lip is retained until a external deflecting force is applied 
to the bending means in an opposite, upward direction. The operation and 
construction of the closure of the present invention will be further 
understood from the following description of the drawings and preferred 
embodiments.

DETAILED DESCRIPTION 
Referring to the drawings, the reference numeral 10 generally indicates a 
closure or lid in accordance with the present invention. Closure 10 is 
intended for use in closing and locking to a container 11 having a wall 
with a radially displaced downwardly extending annular lip 12. Container 
11 can be formed of various materials, including metal or plastic, as 
shown, and may be cylindrical or have a tapered side wall to facilitate 
nesting of a plurality of empty containers. In addition, container 11 may 
have a recessed bottom, as shown, to facilitate stacking of containers 
which have been closed and locked by closures 10 of the present invention. 
In addition, container 11 preferably includes a tapered annular upper wall 
portion 13 (as best shown in FIG. 2), with the annular lip 12 extending 
therefrom. 
Closure 10 has an annular portion 14 adapted to be disposed in contact with 
a portion 15 of the annular lip 12 of container 11. Closure 10 further 
includes shoulder means extending from annular portion 14 for lockingly 
engaging annular lip 12 of container 11. In the embodiment shown in FIGS. 
1-3, the shoulder means extending from annular portion 14 is an annular 
shoulder 16 which is adapted to pivot about the end of annular lip 12 of 
container 11 into locking engagement therewith. Shoulder 16 is illustrated 
as forming an annular edge 17, although other configurations, such as a 
flat or rounded surface in cross section can be utilized. 
Closure 10 further includes deflectable bending means adjacent the shoulder 
means for deflecting the shoulder means about annular lip 12 of container 
11. In the embodiment shown in FIGS. 1-3, the bending means comprises an 
annular wall 18 extending from shoulder 16. Annular wall 18 may be of 
uniform thickness and may be relatively rigid or pliable with respect to 
the remainder of closure 10. 
Closure 10 preferably includes an annular wall 19, positioned inwardly of 
annular portion 14 and having at least one portion 20 which is adapted to 
contact a portion of wall 13 upon annular portion 14 of closure 10 being 
placed into contact with portion 15 of lip 12. Upon contact of both 
annular portion 14 and portion 20 of wall 19 of closure 10 with lip 12 and 
tapered wall 13 of container 11, respectively, at least two areas of 
sealing between closure 10 and container 11 are established, as best shown 
in FIG. 3. Wall 19 can be tapered and can be a part of an annular well 
formed by a second wall 21 and a bottom 22. 
Furthermore, in the embodiment shown in FIGS. 1-3, closure 10 includes an 
annular portion 23 of less strength than portion 14 which is positioned 
adjacent the shoulder means, in this embodiment shoulder 16. Portion 23 
may have less strength than portion 14 by having a narrower cross-section 
than portion 14. Annular portion 23, having less strength than portion 14, 
serves as an area of pivoting of the shoulder means as the latter is 
placed into and out of locking engagement with annular lip 12 of container 
11 upon deflection of the bending means, e.g. wall 18, between its 
upwardly and downwardly positions. 
Reference is made to FIGS. 8-11 and also FIGS. 1-3, reference numerals in 
the latter being utilized in the simplified views of the former to 
describe similar elements, for the purpose of illustrating the principle 
of operation of the closure of the present invention. To close and secure 
an opening in a container 11, closure 10 is placed over and into the 
opening with annular portion 14 of closure 10 in contact with portion 15 
of lip 12 of the container, and with portion 20 of wall 19 in contact with 
tapered wall 13 of the container. Assuming that FIGS. 9 and 10 represent a 
portion of the annular wall 18 of closure 10, arrow 30 indicates the 
position (diameter if FIG. 9 was drawn in full as in FIG. 10) of the edge 
of wall 18 (the bending means) at its upper, unstressed, unlocked 
position. Arrow 31 indicates the position (similarly the diameter) of the 
edge of wall 18 at its lower, unstressed, locked position with the wall 
being shown in broken lines and designated by numeral 18a. Arrow 32 
indicates the position (again similarly the diameter) of the lower limit 
of wall 18, i.e. at its junction with the shoulder means upon wall 18 
being at its upper, unstressed, unlocked position. 
Upon application of a force to the edge of wall 18 as indicated by arrow 
33, with a reaction indicated by arrow 34, as the force applied at 33 
increases, wall 18 will deflect downwardly and outwardly approaching the 
position indicated as 18b. During the application of force at 33, the 
upper portion of wall 18 is subjected to increased internal tension due to 
the increase in the diameter of wall 18 from the position indicated by 
arrow 30 to the position indicated by arrow 35. As the material of closure 
10 is resilient, the lower or inner limit of wall 18 is forced into 
compression and tends to reduce in the diameter thereof from the position 
indicated by arrow 32 to the position indicated by arrow 36. 
Continued downward application of force as indicated by arrow 33 to the 
edge of wall 18 beyond its position indicated as 18b, results in further 
movement of wall 18 along path 37 to a final, locked position indicated at 
18a. At this position the edge of wall 18 will be at the position 
indicated by arrow 31, at which the edge of wall 18 has the same diameter 
as the original diameter indicated by arrow 30, and wall 18 is unstressed 
with its lower limit again at a position or diameter indicated by arrow 
32. At this position, there is essentially zero tension, i.e. no stress, 
on wall 18 which would tend to cause the bending means, i.e. wall 18, to 
return to its unlocked position. It will be understood that the maximum 
stress conditions are reached when wall 18 is in position 18b, which 
position provides self-energized stress relief, conveniently termed snap 
action, by movement upwardly or downwardly along path 37 from position 
18b. 
In order to unlock the closure from the container, a force is applied to 
wall 18, which is now in position 18a, in the direction indicated by arrow 
38 to again cause wall 18 to be stressed and to be moved through position 
18b and deflected so that its lower or inner limit (diameter) is deflected 
from position 32 to position 36. The deflection continues until wall 18 
reaches the position indicated by the numeral 18 in FIG. 9, and the lower 
or inner limit of wall 18 again reaches the position or diameter indicated 
by numeral 32. As shown in FIG. 9, the force applied at 33 or 38 is a 
maximum at the zero stress condition, i.e. when wall 18 is as shown in 
FIG. 9 or at position 18a; and the applied force is at a minimum when wall 
18 is at position 18b. The magnitude of the forces are thus a function of 
the angle between the position of the wall and the vertical, as indicated 
in FIG. 9 by the letter A. 
FIG. 10 further illustrates the operation of the closure of embodiments 
FIGS. 1-3 in full circular condition. Upon the application of a single 
peripheral force to wall 18 in the direction and at the point indicated by 
arrow 40, the portion of wall 18 beneath arrow 40 is moved outwardly 
towards the position indicated by numeral 18c. In the movement of wall 18 
to position 18c, the diametrically opposed portion of wall 18, indicated 
by numeral 41 for convenience, is drawn inwardly to a position, which for 
the sake of illustration is indicated by numeral 41a. Concurrently, all 
circumferential points of wall 18 will be drawn inwardly in some degree 
resulting in an ovate shape of the outer edge of wall 18. The described 
movement reduces the force required to achieve the over center or 
unstressed condition of wall 18 indicated by position 18a. Portion 41 will 
be in position 41b at this time. The transfer of the force from the 
position indicated by arrow 40 to portion 41 at 41b to move the same to 
position 41c, then draws wall 18 from position 18a to position 18d. The 
ovate condition of the edge of wall 18 is similarly increased so that 
portion 41 at position 41c can be brought over center to position 41d 
where the angular relationship of all circumferential points will be equal 
and at zero or minimal internal stress, as illustrated by positions 18a 
and 41d. Thus, it can be seen that a single movable force first applied at 
and in the direction indicated by arrow 40 for causing the closing and 
locking operation of the closure will be considerably less than a force 
applied to the entire periphery of wall 18. Similarly, a lesser single 
movable force need be applied to unlock the closure than an unlocking 
force applied to the entire periphery of wall 18. 
The same principle of operation is applicable where the upper portion of 
wall 18 is reinforced to reduce tensional deformation, as by a lip or ring 
portion of increased thickness with respect to the remainder of wall 18. 
FIG. 11 illustrates the principle where, for illustration purposes, wall 
18 integrally terminates in annular portion 61 of increased thickness. 
Wall 18 and portion 61 will deflect along path 62 upon the application of 
a force in the direction and at the point indicated by arrow 63. As wall 
18 is resilient, wall 18 is deflected to a greater degree than annular 
portion 61 due to the latter's increased thickness and resultant 
resistance to deflection, causing a bend in wall 18 as shown by position 
18e. Furthermore, due to the combination of resilient wall 18 and less 
resilient or less stretchable portion 61, wall 18 will follow path 62 upon 
the continued application of force initially applied as indicated at 63 to 
provide a spring-like, or snap action which will serve to force wall 18 
into the position indicated as 18f. Wall 18 is retained in the latter 
position by the minimizing stress characteristics of annular portion 61, 
maintaining the closure in a securely locked condition until a releasing 
force is applied to wall 18 in the direction indicated by arrow 64. 
In another embodiment of the present invention, as shown in FIGS. 4 and 5, 
wherein elements similar to elements in the embodiment illustrated in 
FIGS. 1-3 are indicated by the same numerals, closure 50 has as its 
bending means a plurality of ribs 51 extending from the shoulder means, 
which in the illustrated embodiment is a plurality of individual shoulders 
52, each extending from annular portion 15 of closure 50 and from which 
extend one of the plurality of ribs 51, but can also be a web as in FIGS. 
1-3. Upon the deflection of ribs 51, individual shoulders 52 are pivoted 
about annular lip 12 of a container 11 (FIGS. 1-3) into and out of locking 
engagement therewith. The plurality of the ribs 51 integrally terminate in 
an annular ring 53 of increased thickness with respect to ribs 51. Annular 
ring 53 will assume an ovate condition upon the application of locking or 
unlocking force to a single point or a small portion along the periphery 
of ring 53, in a manner similar to that described in connection with FIGS. 
8-11. Closure 50 can include an annular portion 23 of less strength to 
serve as a hinge or pivot point as in the first embodiment, for the 
deflection of shoulders 52 about a lip 12 of a container 11. 
FIG. 6 illustrates still another embodiment of the present invention 
wherein elements similar to elements in the embodiment shown in FIGS. 1-3 
are indicated by the same reference numerals, and need not be further 
described. Referring to FIG. 6, closure 60 has an annular wall 18 which is 
substantially of uniform thickness, or can have a thickness which 
increases progressively away from shoulder 16. Wall 18 integrally 
terminates in an annular portion 61 of increased thickness with respect to 
the thickness of the remainder of wall 18. Wall 18 and portion 61 will 
deflect axially along path 62 through the positions indicated in broken 
line upon the application of a force in the direction and at the point 
indicated by arrows 63 or 64, as heretofore described in connection with 
FIG. 11. Wall 18 is retained in the position indicated as 18f with 
shoulder 16 pivoted about and locked to lip 12 by the minimizing stress 
characteristics of annular portion 61, maintaining closure 60 in a 
securely locked condition until a releasing force is applied to wall 18 in 
the direction indicated by arrow 64. 
FIG. 7 illustrates another embodiment of the present invention wherein 
elements similar to elements illustrated in FIGS. 4 and 5 are referred to 
by the same reference numerals. In this embodiment, closure 70 includes as 
shoulder means an annular shoulder 16 extending from annular portion 14 as 
previously described in connection with FIGS. 1-3, but can also be a 
plurality of shoulders as in FIGS. 4 and 5. However, in this embodiment, 
the bending means comprise a plurality of ribs or spokes 71 which 
terminate integrally in an annular ring 72. Ribs or spokes 71 function as 
previously described in connection with the embodiment shown in FIGS. 4 
and 5. Ring 72 in combination with ribs or spokes 71 provide an over 
center snap action as previously described. 
It is seen from the foregoing that the closure of the present invention 
through its bending means, preferably in the form of an annular wall or a 
plurality of ribs or spokes, provides a mechanical leverage system which 
pivots shoulder means into and out of locking engagement with the lip of a 
container. In the locked or unlocked position, the closure is at a 
condition of zero internal stress, and hence is in a condition of maximum 
stability; whereas the closure is in a condition of maximum internal 
stress, and hence maximum instability, while the closure is being 
deflected from either its locked to its unlocked condition or from its 
unlocked to its locked condition. The closure provides an over-center snap 
action between the unlocked and locked conditions to facilitate locking 
and unlocking, and to retain the closure in either condition without the 
application of additional force or retaining means. 
Various changes coming within the spirit of the invention may suggest 
themselves to those skilled in the art; hence the invention is not limited 
to the specific embodiments shown or described and uses mentioned, but the 
same is intended to be merely exemplary, the scope of the invention being 
limited only by the appended claims.