U.S. patent number 3,831,822 [Application Number 05/344,057] was granted by the patent office on 1974-08-27 for safety aerosol can.
This patent grant is currently assigned to National Can Corporation. Invention is credited to Arthur P. Zundel.
United States Patent |
3,831,822 |
Zundel |
* August 27, 1974 |
SAFETY AEROSOL CAN
Abstract
The invention disclosed here relates to a safety vent for
pressurized containers consisting of a relief pressure area in a
wall of the container with crowning means within the relief
pressure area that produces a crown when the pressure in the
container exceeds a predetermined safe limit. The relief pressure
area is defined by a pair of spaced, weakened portions that are
separated from each other by unweakened portions. In one embodiment
the crowning means is a bead that extends generally parallel to the
weakened portions and in another embodiment a plurality of weakened
lines extending generally normal to the weakened portions define
the crowning means.
Inventors: |
Zundel; Arthur P. (Mt.
Prospect, IL) |
Assignee: |
National Can Corporation
(Chicago, IL)
|
[*] Notice: |
The portion of the term of this patent
subsequent to April 3, 1990 has been disclaimed. |
Family
ID: |
26948986 |
Appl.
No.: |
05/344,057 |
Filed: |
March 22, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
262050 |
Jun 12, 1973 |
3724727 |
Apr 3, 1973 |
|
|
Current U.S.
Class: |
222/397;
220/89.2 |
Current CPC
Class: |
B65D
83/70 (20130101); B05B 15/14 (20180201) |
Current International
Class: |
B65D
83/14 (20060101); B65d 083/14 () |
Field of
Search: |
;222/396,397
;220/44C,44D,44R,89A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tollberg; Stanley H .
Attorney, Agent or Firm: Dressler, Goldsmith, Clement &
Gordon, Ltd.
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of application Ser. No.
262,050 filed June 12, 1972, which matures into U.S. Pat. No.
3,724,727 on Apr. 3, 1973.
Claims
I claim:
1. A safety vent for pressurized containers such as aerosol
containers and the like comprising a pair of spaced opposed arcuate
weakened lines defined in said wall with said weakened lines having
opposite ends, the adjacent ends of adjacent weakened lines being
separated from each other by unweakened portions and cooperating
therewith to define a pressure relief section, rigidifying means in
said wall, said rigidifying means being located adjacent each
unweakened portion outside planes extending through said adjacent
ends of adjacent weakened lines, and crowning means between said
pair of weakened lines, said crowning means producing a bulge
between said weakened lines when the pressure within the container
exceeds a certain level to sever said weakened lines, said
rigidifying means maintaining said wall adjacent each weakened
portion in substantially the original condition.
2. A safety vent as defined in claim 1, in which said wall is an
end of the container.
3. A safety vent as defined in claim 2, in which said end wall is
arcuate in cross-section to define a concave outer surface.
4. A safety vent as defined in claim 1, in which said crowning
means is an elongated bead deformed outwardly of said wall, said
bead extending generally parallel between said weakened lines.
5. A safety vent as defined in claim 4, in which said rigidifying
means each includes a plurality of inwardly directed beads.
6. A safety vent as defined in claim 5, in which each rigidifying
means includes three equally spaced beads.
7. A safety vent as defined in claim 1, in which said pair of
weakened lines have a common radius located at a common center
between said weakened portions to define a circular relief pressure
section and in which said crowning means extends through said
common center.
8. A safety vent as defined in claim 7, in which said crowning
means includes an outwardly directed elongated bead having opposite
ends terminating inwardly and in close proximity to the periphery
of the circular relief pressure section.
9. A safety vent as defined in claim 8, further including a
plurality of radially extending inwardly directed beads located
adjacent each of said unweakened portions outside of said circular
relief pressure section.
10. A safety vent as defined in claim 9, in which said relief
pressure section is defined in a circular end wall of the container
and the diameter of the relief pressure section is approximately
one-half the diameter of the circular end wall.
11. A safety vent as defined in claim 9, in which there are three
radially extending beads adjacent each unweakened portion and the
radially extending beads adjacent each unweakened portion are
equally spaced from each other.
12. In an aerosol container having a cylindrical side wall and
upper and lower end walls, a plurality of circumferentially spaced
arcuate weakened lines having opposite ends with adjacent ends
spaced from each other to define a plurality of unweakened portions
between adjacent ends of the adjacent weakened lines, said weakened
lines defining a circular pressure relief section; and elongated
crowning means having opposite ends terminating inside said
circular pressure relief section, said weakened lines being severed
when the pressure in said container exceeds a predetermined level
and said crowning means causing an outward bulge between the
weakened lines with the center of the bulge located generally along
said crowning means.
13. An aerosol container as defined in claim 12, in which said
elongated crowning means is an outwardly directed bead having
opposite ends located adjacent opposed unweakened portions.
14. An aerosol container as defined in claim 12, in which said
relief section has a diameter of approximately one-half the
diameter of said lower end wall.
15. An aerosol container as defined in claim 12, in which said
lower end wall has a concave outer surface in cross-section, the
periphery of which is joined to said side wall, and in which said
relief section is dimensioned to be maintained above the periphery
of said lower end wall after said weakened lines have been
severed.
16. An aerosol container as defined in claim 13, further including
a plurality of equally spaced, radially extending, inwardly
directed beads located adjacent each unweakened portion outside
said circular pressure relief section to ridigify the end wall
adjacent each unweakened portion.
17. An aerosol container as defined in claim 12, in which said
lower end wall is arcuate in cross-section to define a concave
outer surface having a common radius and in which the center of
circular pressure relief section is located at the center of said
lower end wall.
18. An aerosol container as defined in claim 12, in which said
lower end wall is arcuate and defines an outer concave surface that
has a first radius adjacent the periphery of the lower end wall and
a second radius greater than the first radius at the center of said
lower end wall.
19. An aerosol container defined in claim 12, in which said lower
end wall has an arcuate concave annular portion adjacent the
periphery thereof and a flat portion inside said annular portion
and in which said relief pressure area is defined in said flat
portion.
20. An aerosol container as defined in claim 12, in which said
crowning means includes a plurality of weakened lines extending
generally normal to said weakened portions and terminating in
spaced relation at opposite ends thereof.
21. An aerosol container as defined in claim 12, in which each of
said circular weakened portions has a circumferential dimension
substantially greater than 90.degree. and less than 180.degree..
Description
BACKGROUND OF THE INVENTION
Pressurized dispensing containers and the like are now well known
and are widely used for packaging and dispensing such products as
hair spray, shaving lather, and food products. Most often such
products are mixed with a FDA approved propellant which is gaseous
at room temperature and pressure. Most often such dispensing
containers are referred to as aerosol containers. It is necessary
that such aerosol containers be safely suited for utilization
including their transportation from point to point and their
ultimate disposal as through home or commercial incineration and/or
compaction.
Several mechanisms for accomplishing the above objectives have been
proposed by the container industry including a mechanism called
"rim vent release" wherein slight notches or cuts are formed in the
can stock which ultimately makes up that portion of the can known
as the double seam so that upon inversion of the notched end of the
container upon a pressure increase above a predetermined safe
level, the movement of this end uncovers and splits such weakened
areas to produce venting. Such a container is described in U.S.
Pat. No. 2,795,350 to Lapin. To date such construction has not been
fully commercialized.
Other mechanisms and constructions representing further approaches
to provide a safety pressurized container of the type described
have been suggested and proposed. One such approach includes the
use of a weakened line or lines defining an area within the
container wall which is subject to tearing or opening upon
increased pressure beyond a certain predetermined safe pressure
limit. It has been found, however, that in many cases these
weakened areas are subject to complete and sudden removal from the
container wall and thus although in part providing a vent means
also present a related safety hazard of their own in the form of a
projectile.
It has also been suggested to utilize heat fusible plugs tightly
fitted into openings provided in the container walls. Such have
proven satisfactory in those instances wherein the increased
pressure above a predetermined safe level within the container is
caused by an even application of heat. Obviously such ideal
conditions are not always present nor has such proposed solution
any application when increased pressures are caused by crushing
forces such as would be brought about through the use of compaction
devices such as those now finding increase use in household
kitchens.
SUMMARY OF THE INVENTION
The present invention provides a safety vent for pressurized
containers which obviates the above difficulties of prior art
devices and which is extremely simple in design and structure,
inconspicuous in application and inexpensive to incorporate into
the normal pressurized aerosol container constructions.
The safety vent means consists of a relief pressure area that is
located in one wall of a container, preferably the lower end wall.
The relief pressure area is defined by a pair of opposed arcuate
weakened portions that are separated from each other by spaced
unweakened portions with crowing means located between the pair of
weakened portions. The crowing means will produce a bulge or
outward crown in the relief pressure area when the pressure in the
container exceeds a predetermined level which will cause a
stretching of the metal and ultimate severing or rupture of the
weakened portions to allow a pressure equalization between the
inside and outside of the container.
In one embodiment, the crowning means consists of a plurality of
parallel weakened lines defined in the metal of the container and
extending generally normal to the arcuate weakened portions
defining the pressure relief area. These weakened lines are located
within the confines of the pressure relief area and the residual
metal in the parallel weakened lines is greater than the residual
metal in the weakened portions.
In another embodiment, the crowning means consists of an outwardly
directed bead that extends generally parallel between the two
opposed weakened portions and the opposite ends of the bead
terminate adjacent but inside the area defining the pressure relief
area in the wall of the container. In this embodiment, the
container wall also has rigidifying means in the form of spaced
inwardly directed beads that are located adjacent the unweakened
portions and outside of the area that defines the pressure relief
area in the wall of the container.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a pressurized dispensing container
incorporating the safety vent means of my present invention;
FIG. 2 is a bottom plan view of the container shown in FIG. 1
showing one version of safety vent means provided in the container
lower end wall, the vent means being depicted in a closed unvented
state prior to subjection to forces above a predetermined safety
level;
FIG. 3 is a perspective view of a base portion of the container
shown in FIG. 1 on a slightly enlarged scale and showing the safety
vent means provided therein in an open vented position;
FIG. 4 is a cross-sectional view taken on the line 4--4 of FIG. 3
showing one manner in which the vent means of the present invention
operates;
FIG. 5 is a cross-sectional view similar to FIG. 4 showing another
manner in which the vent means of the present invention
operates;
FIG. 6 is a partial cross-sectional view taken on the line 6--6 of
FIG. 2;
FIG. 7 is a bottom plan view of the container similar to the view
shown in FIG. 2 and showing a modified type of safety vent means
provided in the lower end wall;
FIG. 8 is a transverse-sectional view as viewed along line 8--8 of
FIG. 7;
FIG. 9 is a bottom plan view similar to FIG. 7 showing the modified
safety vent means in the container lower end wall that is concave
in cross-section:
FIG. 10 is a transverse-sectional view as viewed along line 10--10
of FIG. 9;
FIG. 11 is a perspective view of the bottom portion of the
container shown in FIG. 9 showing the safety vent means in a vented
position; and
FIG. 12 is a sectional view as viewed generally along line 12--12
of FIG. 11.
DETAILED DESCRIPTION
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and will herein be described
in detail several specific embodiments, with the understanding that
the present disclosure is to be considered as an exemplification of
the principles of the invention and is not intended to limit the
invention to the embodiments illustrated.
Referring now to the drawings wherein like reference characters
designate the same or corresponding parts throughout the several
views and more particularly to FIG. 1 and FIG. 2 thereof, the
safety vent of the present invention is shown. An aerosol
dispensing container 10 is depicted as formed from a cylindrical
side wall portion 12 provided with base and top wall closures 14
and 16 at opposite ends. Such end walls 14 and 16 may be attached
to the side wall portion 12 of the container 10 by means of
conventional double seams 18. Alternately the container may be
formed of two piece construction wherein the bottom wall 14 is
integral with the side wall 12. It should also be understood that
the safety means of the present invention may be incorporated to
other areas of the container other than the lower end wall or base
14. Also, while the present container will be referred to as an
aerosol dispensing container, such terms should be recognized as a
term of art and inclusive of other pressurized containers. The
container 10 is further provided with a dispensing means 20 of
conventional construction.
The pressure relief area 22 is depicted of circular configuration
but may take on other shapes and configurations within the
following general constructional framework, wherein such pressure
relief area 22 is comprised of a first set or pair of weakened line
portions 24 generally opposed to each other and separated by spaced
unweakened wall portions 26. The relief pressure area, defined by
weakened portions 24 and unweakened portions 26, has crowning means
between the weakened portions that produce a crown, as will be
described later. In the embodiment illustrated in FIGS. 1-6, the
crowning means consists of a second weakened line portion 28 that
is positioned within the pressure relief area 22 and preferably
incudes an odd number of weakened lines 30; 3 being depicted in the
drawings. Other odd numbered, e.g. 1,5, etc. lines 30 might be
utilized for a purpose which will be hereinafter made apparent.
The weakened lines 24, as are the weakened lines 30, are formed in
a conventional manner such as scored lines formed in the end wall
14 of the can 10. Such scoring can be formed on the ends while in a
flat blank form and prior to being double seamed onto the container
body 12. The scoring to form the weakened lines 24 is deeper than
that forming the weakened lines 30, and accordingly pressure within
the container 10 above a predetermined level will initiate rupture
along either or both lines 24 while simultaneously permitting
bending or crowning of the relief pressure area along the second
weakened line portion 28 as best depicted in the cross-sectional
views showing rupture pressure relief area configurations in FIGS.
4 and 5.
An inspection of FIG. 2, reveals that the relief pressure defined
by weakened and unweakened portions 24 and 26 is circular in plan
and that the diameter of relief pressure area 22 is approximately
one-half and preferably slightly less than one-half the diameter of
the circular lower end 14. Also, the arcuate weakened portions 24
each have a circumferential dimension substantially greater than
90.degree. but less than 180.degree. and the center weakened line
30 passes through the center of the circular relief pressure
area.
FIG. 4 shows the ruptured or open vented condition of the pressure
relief area 22 wherein tearing or rupture was initiated along the
left hand weakened portion 24 and FIG. 5 depicts that condition
wherein tearing was initiated along both weakened portions 24
simultaneously. The characteristic tentlike construction shown in
both FIG. 4 and 5 is brought about by the co-action of the end
openings 32 formed by the tearing of one or more of the weakened
line portions 24 and the second weakened line portion 28 permitting
the upward travel of the pressure relief area 22 about the
unweakened wall portions 26. Bending occurs along the central
portion of the weakened line portion 28 which in turn contributes
to the formation of a stiffening tent-like structure thus reducing
the chance of continued tearing along the weakened lines 24 into
the unweakened wall portions 26 which could cause undesirable
complete or partial tear-out of the entire pressure relief area 22.
The use of an odd number of weakened lines 30 contributes in the
formation of a central bend line which in turn forms the central
ridge of the pressure resisting tent-like configurations shown in
FIG. 4 and 5 of the drawings. During the formation of the tent-like
configuration, metal flows from the periphery of the lower end wall
through the unweakened portions 26 into the relief pressure
area.
Obviously, numerous modifications and variations of the present
invention are possible in light of the above teachings. By way of
example more than two weakened line portions 24 may be provided.
For example, should three such areas be provided and each spaced
from each other the second weakened line portions 28 would be more
radially disposed within the pressure relief area 22 and directed
towards the mid-point of one or more of such weakened lines. Also,
depending on the differential pressure contemplated, several
parameters such as container material and thickness, as well as
scoring depths to form weakened line portions 24 and 28 may be
provided. Thus, the individual lines 30 making up the second
weakened line portion 28 may vary in scored depth, such variation
decreasing outwardly so as to emphasize the tent effect described
above.
A slightly modified form of relief pressure are defining a safety
vent means is shown in FIGS. 7-12. In FIG. 7, the modified relief
pressure area is illustrated in a container similar to that shown
in FIGS. 1-2 which is commonly referred to as a "stacker" container
while FIGS. 9-12 show the modified relief pressure area in a
container that has a concave lower end wall. Since the two pressure
relief areas shown in the respective types of containers are
substantially identical in the construction, like reference
numerals will be utilized for both versions of the container.
In FIGS. 7 and 8, the lower end wall 50 is configured to allow
containers to be stacked end-on-end before the dispensing means 20
is located in the top wall closure of the container. For this
purpose, the container lower end wall or closure has an arcuate
annular portion 52 that is connected to the lower end of
cylindrical side wall 12 of the container through the conventional
double seam 18. Lower end wall 50 also has a planar flat portion 54
located inside the annular portion 52 and separated therefrom by an
inwardly directed circular bead 56.
The container end wall 60 shown in FIGS. 9-12 is generally referred
to as a "concave" or "regular" container end in which the lower end
wall is arcuate in cross-section to define a concave outer surface
62 and the periphery of the concave end wall 62 is connected to
container side wall 12 through double seam 64. The outer concave
surface 62 has a constant radius. In another version (not shown)
the lower end wall is also concave in cross-section, but the
concave surface has a first radius of curvature adjacent the
periphery and a second radius of curvature adjacent the center of
the end wall which is greater than the first radius of the area
adjacent the periphery of the circular end wall.
As indicated above, pressure relief areas 70 for the two container
end walls shown, respectively in FIGS. 7 and 9, are identical in
construction so that only one will be described in detail.
Referring to FIG. 9, pressure relief area 70 that defines the
safety vent means for the pressurized container consists of a pair
of spaced weakened portions 72 that are separated from each other
by spaced unweakened portions 74. As most clearly shown in FIG. 9,
the weakened portions are arcuate and have a common radius that is
located at a common center 76 between the two weakened portions so
that the pressure relief area that defines the safety vent is
circular in plan view. The pressure relief means also includes
crowning means 78 between the two weakened portions 72 and the
crowning means will produce a crown or tent-like construction
substantially between the weakened portions 72 when the pressure
within the container exceeds a certain level, as will be explained
in more detail later. In the embodiment illustrated in FIGS. 7-12,
the crowning means consists of an elongated bead 80 that is
deformed outwardly in the body of the circular end wall 50 or 60.
The elongated bead has opposite ends terminating inside the
circular relief area as is most clearly shown in FIGS. 7 and 9.
The lower end wall of th container also has rigidifying means 84
adjacent each of the unweakened portions 74 to maintain the area of
the container adjacent the weakened portions 74 in substantially
the original condition. In the illustrated embodiment, the
rigidifying means consists of a plurality of equally spaced beads
86 that are deformed inwardly in the container end wall and are
equally spaced from each other. The respective beads 86 extend
radially from the center 76 of the pressure relief area and are
located adjacent each of the unweakened portions 74 outside of the
circular pressure relief area 70. It has been found that the number
and specific location of the inwardly directed beads 86 is
important, as will be explained later.
When an excess pressure above a predetermined level is developed
within the container, the pressure relief area 70 will act in a
manner similar to that described in connection with the relief area
shown in FIGS. 1-6. A predetermined pressure will cause an initial
outward bulging or tenting of the circular pressure relief area 70
generally longitudinally between the two spaced weakened portions
72.
The longitudinal bead 80, more particularly the location, direction
and configuration will insure that the pressure relief area will
tent or bulge outwardly and that the center of the bulging portion
is located substantially equally between the two weakened portions
72. This necessarily results since the outwardly deformed bead will
weaken the container end along the center of the bead which will
therefore be the first area that will be distorted when the
pressure reaches the predetermined level.
During the bulging or crowning of the area of the end between the
weakened portions or lines 72, the additional metal that is
required to produce the crowning or tenting will produce a
stretching of the metal inside the weakened portions 72 to result
in the severance of the weakened portions 72. During this outward
bulging or tenting, there will be some metal flow from the
periphery of the wall between the rigidifying beads which will
allow sufficient bulging or crowning to cause severance of the
weakened portions. However, the rigidifying means 84 will constrain
the crowning substantially within the confines of the pressure
relief area and will maintain the area outside of the pressure
relief area in its original condition.
As was indicated above, the specific number and location of the
inwardly directly equally spaced, radially extending beads has been
found to be critical. It has been found that if there are too many
beads that are located in close proximity to each other, there will
not be sufficient metal flow from the periphery of the container
end wall into the circular relief pressure area to allow the
crowning effect to sever the weakened portions 72 and if there are
an insufficient number of beads there will be too much metal flow
and insufficient rigidity so that the entire end will bulge. It has
been found that three equally spaced radially extending beads
adjacent each of the unweakened portions will produce a sufficient
rigidity to prevent a crowning of the area outside of the beads 86
while still allowing sufficient metal flow between the adjacent
beads through the unweakened portions 74 into the circular pressure
relief area to allow adequate crowning of the area between the
weakened lines and sever the weakened portions 72.
The final configuration of the end wall of the container after the
pressure relief area 70 has been ruptured is depicted in FIGS. 11
and 12. It will be noted that the bending of the pressure relief
area will be along a line that extends generally through the base
of the longitudinally extending bead 80. It has also been found
that the depth of the deformation and the length of bead 80 will
determine the pressure at which the pressure relief area will begin
to crown or "tent." Thus, the depth of the bead can be utilized to
vary the pressure at which the safety vent means will become
operative.
It has also been found that the rigidifying means or beads 86 will
prevent severing of the end wall of the container beyond opposite
ends of the weakened portions 72. This is important since a
severing beyond the desired location may result in a complete
removal of the weakened section which could then act as shrapnel
that could seriously injure a person in close proximity to the
container.
It has also been found desirable to maintain the pressure relief
area within the confines of the lower rim or end of the container
even after the pressure relief area has been ruptured. This has
been accomplished by the particular relative dimensions of the
circular pressure area in relation to the diameter of the circular
end wall 60 or 70. For example, it has been found that if the
circular pressure relief area 70 is made with a diameter that is
approximately one-half and preferably less than one-half of the
diameter of the lower end wall 60 or 70, the bulging of the wall
within the confines of the weakened portions 72 will be limited so
that the pressure relief area is maintained above the peripheral
edge of the concave wall at all times.
While the rigidifying means has been shown only in the embodiment
of the invention shown in FIGS. 7-12, it will be appreciated that
such a feature could be incorporated into the embodiment shown in
FIGS. 1-6. Also, in some applications of the container end wall
shown in FIG. 7, it may be necessary or desirable to have the
weakened portions located outside bead 56.
* * * * *