Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION. This invention pertains
to electric storage battery vent caps comprising first and second
members. More particularly, it pertains to battery vents which
greatly reduce the potential for explosions within the battery.
This is accomplished by designing ~he vent cap in such a manner
to vent battery gases through at least one very narrow passage
formed between said first and second members.
DESCRIPTION OF THE PRIOR ART. A common problem
in the battery indastry today is the occurrence of battery
explosions, generally occurring while the battery is receiving
a fast charge of being jumped. When too high a current is applied
for too long a time, large amounts of ~ydrogen and oxygen may be
evolved by the electrolysis of water in the sulfuric acid
solution. These gases must be vented, but should they be ignited
by a flame or spark generated at the battery terminals, the
resulting flame can propagate back into the battery cells causing
the battery to explode. The exp~loding battery will spray sulfuric
acid which can cause severe burns and blindness if contacted with
the skin or eyes.
The prior art has recognized this problem and has
responded by placing a rectangular porous ceramic insert into the
battery vent, through which the battery gases are vented. This
means performs well, but is unsatisfactory from the standpoint
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of cost. The insert itself is costly and requires that
additional steps be taken ~o fabricate the battery vent, which -:
makes the process more expensive as well. .-.
I have invented a battery vent which is efficient
in reducing the likelihood of battery explosions and yet is : .
simple and inexpensive to fabricate. By properly designing a
vent path between the first and second members of the battery
vent, the p00ous insert can be eliminated.
SUMMARY OF THE INVENTION
Broadly, the invention resides in a battery vent
comprising first and second members, a vent means, for example,
at least one vent hole on at least one of said members, and a
means on said second member for attachment to a battery through
which gas can pass, wherein said first and second members fit
closely together in such a manner that substantially all gas
generated within a battery passes through at least.one narrow
passage formed between~s~id~fir.~t and~.second mem~ers-.to sai
vent means. The narrow passage between the first and second ?,'.
members may be created by at least one shallow groove in either
mem~er or bot~l or a~ternativelx b~ flexure of one member.
In one.aspect, the battery vent may have a
plurality of bosses on the second member which depend into the :~
battery lid and wherein there are a plurality of shallow grooves . -
in the second member, each separately located between adjacent
bosses such that each shallow groove is in communication with -
the void spaces within each boss, allowing each shallow groove to -
function as a narrow passage for both adjacent bosses simultan-
eously. At least one vent hole is placed in communication with ~. .
each shallow groove.
In a further aspect, each narrow passage may be ~
formed by the intersection of two shallow grooves resulting in :
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a cross-shaped narrow passage. Each cross-shaped narrow passage
is ~eparately located between adjacent bosses of the second
member and one of said intersecting shallow grooves is in
communication with the void spaces within each boss. The other
intersecting shallow groove provides a place for at least one
vent hole in communication with the narrow passage.
In a further aspect, the invention resides in a
battery vent wherein the first member is attached to the second
member in such a manner to leave substantially no clearance
between corresponding portions of said first and second members,
wherein the first member is flexible, and wherein substantially
all gas generated within a battery vents through a narrow passage ~`-
formed between said first and second members when internal
pressure forces the first member to flex. A battery vent having
this venting means may be either a gang vent (multiple cell) or
a single-cell vent.
In a still further aspect, the invention resides
in a battery lid wherein the aforesaid second member is actually
an integral part of the lid and the first member has at least
one vent hole. In the same manner as the previous aspects, the ,
first member fits closely together with the second member so that
substantially all gas generated within a battery passes through
at least one narrow passage formed between said first and second
members. `
In a still further aspect of this invention there ;
is provided a battery ~ent comprising~
(a) a first member;
(b) a second member positioned closely adjacent `~ -~
to said first member; ~-
(c) a vent means;
(d) a narrow passage formed between said first and
second members in gaseous communication with said vent means,
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said narrow passage having a depth between 0.001 and 0.015
inch and a length such that venting gases must travel at least .
0.18 inch through said narrow passage; and
(e) means on said second member for attachment to
a battery through which gas can pass from the battery to said
narrow passage, wherein said battery vent acts to inhibit
battery explosions.
In a still further aspect of this invention there
is provided a battery lid comprising: ;
(a) a first member;
(b) a second member which is an integral part
of the battery and positioned closely adjacent to said first
member; "
(c) at least one vent hole in said first member; ~
(d) a narrow passage formed between said first and ~-
second members in gaseous communict~mon with said vent hole(s),
said narrow passage having a length such that venting gases
must travei at least 0.18 inch through said narrow passage and `~
a depth between 0.001 and 0.015 inch; and
(e) means on said second member for attachment
to a battery through which gas can pass from the battery to said
narrow passage, wherein said battery lid acts to inhibit
battery explosions.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a perspective view of a battery
with two gang-type battery vents in place on the lid. :
Figure 2 shows a partially cross-sectional ~ide : .
view of a gang vent having a flexible first member. `
Figure 3 shows a plan view of the second member
shown in Figure 2.
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Figure 4 shows a plan view of the second member
having a single shallow groove between adjacent bosses.
Figure 5 shows a plan view of a second member
having a cross-shaped narrow passage between adjacent bosses.
Figure 6 shows a side view of a first member with
at least two vent holes, illustrating the baffles.
Figure 7 shows a plan view of a first member
having six optional vent hole locations.
Figure 8 shows a side view of an assembled
single cell vent. ~;;
Figure 9 shows a bottom view of the first member
of the vent of Figure 8.
Figure l0 shows a bottom view of the second member
of Figure 8. - -
Figure ll shows a side view of the second member
of Figure l0.
Figure 12 shows a cross-sectional view of the
assembled single cell battery vent of Figure 8. ~ ~
DESCRIPTION OF THE P~EFE~RED EMBODIMENTS ~ -
Directing attention to the drawing, my invention
will be described in more detail. `
Figure l shows a battery l with two terminals 2 -
and a pair of gang battery vents 3 in place atop the battery ;
lid 4. Although the gang type battery vents herein illustrated -;
are each designed to vent three battery cells, it is clearly
within the scope of this invention to design the battery vents
to cover any number of battery cells simultaneously. `
Figure 2 shows a partially cross-sectional side
view of a gang vent having a flexible first member 6 with at
least two vent holes 7 ~only one hole visible). Shown is a ~;
skirt 8 around the bottom member; the downwardly protruding ~ -
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bosses 9 which plug the openings in the battery cell cover; an
orifice 11 which allows electrolyte to drain back into the
battery cell; three downwardly protruding cylinders 12 (only two
shown) which prevent splashing electrolyte from entering and
accumulating in the void space 13; and a means for attachment
to a battery comprising an "s-shaped" annular fold 14 which is
flexible enough to adjust for center-to-center errors in the
cell cover ppenings, providing a tight seal between the vent
and the cell cover ~lid). In operation, the battery gases are
generated within each cell and enter the vent through orifice
11, which has a diameter of O.S0 inch. The gases then pass
between the sidewall of the boss 9 and the downwardly protruding
cylinder (baffle) 12 of the first member. It has been found
that the distance between the inner wall of the boss and the
downwardly protruding cylinder may range between 0.002 and 0.015
inch. The gases subsequently pass through void space 13 and
then between the first member 6 and a portion 16 of the second
member before exiting through the vent hole 7. The clearance
between the first member 6 and the second member 16 is sub-
stantially zero until internal pressure created by the evolvingbattery gases causes the first member to flex or bow outward.
The first member is attached to the second member by a sonic
weld around the periphery of the first member, allowing the
first member to bow only in the middle. Thi flexing action
creates a narrow passage between the first and second members
which allows the gases to pass out the vent hole 7. It has been
found that the first member may separate from the second member
a distance between 0.002 and 0.012 inch. This provides room
for adequate gas flow while still preventing propagation of any ;
flame from autside the vent back into the battery.
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Figure 3 shows the second member of Figure 2 viewed
from the top. It illustrates the flat area 16 of the second
member over which venting gases pass prior to reaching the vent
hole. This embodiment can be contrasted with the embodiments
illustrated in Figures 4 and 5, which have a groove in the
second member which channels venting gases directly to the vent
hole. Also shown is the inner periphery 17 of the second member -
to which the first member may be sonic welded.
Figure 4 illustrates another preferred embodiment
of the second member wherein the battery gases pass between the
first and second members via a narrow passage comprising a `
shallow groove 18 in the second member which provides communic- -~
ation between a vent hole in the first member and the void ~-
space 13 of the second member. In this embodiment it is
preferred that the first member be fastened tightly against the
second member to avoid any flexing action. This is easily
accomplished by sonic welding the two members together at `'
various locations 19, as well as around the periphery of the
first member. The purpose of the shallow groove 18 is to pro-
vide dimensionally controlled flow of the gases which would be
defeated by flexure of the first member.
Figure 5 illustrates the most preferred embodiment
of the second member for a gang-type vent. It differs from `-
that shown in Figure 4 only in the configuration of the narrow
passage. This embodiment employs a cross-shaped narrow passage
21 comprising the intersection of two g~nerally straight shallow
grooves in the second member, wherein each cross-shaped narrow
passage is separately located between two adjacent bosses. One of i-
the two intersecting shallow grooves provides communication
between the void space within the two adjacent bosses. The
other shallow groove provides communication with at least one
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vent hole in the first member, preferably a plurality of vent
holes. It is also preferred that all vent holes be located
such that every molecule of venting gases must travel throu~h
the narrow passage a distance of at least 0.18 inch. This
applies to all embodiments of this invention. Shorter paths
would lessen the ability of the battery vent to prevent flame
propagation back into the battery. Also, the depth of each
shallow groove should be at least 0.001 inch to allow free flow
of gases but not more than 0.015 inch to prevent flame propagation.
No restrictions on the width of the narrow passage are known.
Also, as indicated in Figure 4, the first member should remain
close as poss~ble to the second member during operation, thus
soqUir$ng additional ~eld loc-~ion8 19.
Figure 6 shows a side vie~ of the mo~t proforred
embodiment of the first member for a gang-type battery vent.
This design is the same as that shown in Figure 2. Shown is
the generally flat portion 6 of the first member with a thickness
of 0.03 inch, the vent hole locations 7, and the downwardly -
protruding cylinders (baffles) 12. The material of the first
member is polypropylene, as is the second member, but the
invention should not be construed as being llmited to any specific
material.
Figure 7 shows a plan view of the first member as
viewed from above. It illustrates two sets of three possible
locations for vent holes. Any combination of vent holes may be ~ -
used, providing there is at least one vent hole for each narrow ;
passage located between adjacent bosses. As indicated in this
figure and those previously described, it is preferred that the
vent holes be located in the first member and the shallow grooves
be located in the second member. This, however, may be reversed
without exceeding the scope of this invention. The primary
purpose for venting gases through the first member is that there
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are no pockets within the exterior of the first member in which
vented gases could collect. Underneath the second member, how-
ever, there are places where the hydrogen might be trapped,
causing an explosion hazard. The size of the vent holes may
vary between 0.01 inch to 0.13 inch in diameter. In the prefer-
red embodiment the vent hole diameter is 0.03 inch, there being
four symmetrically-spaced vent holes.
Figure 8 shows a side view of a single-cell battery
vent of the screw-on variety. The means by which flame
propagation is retarded in this embodiment is the same as that
for the gang-type battery vent of Figure 2, i.e. the venting
battery gases pass between a narrow passage formed between first
and second members. Shown in this figure are two optional
protrusions 5 which contain the vent holes located on the first ;
member, finger grips 22 located around the periphery of the
first member, and the threaded cylinder 23 of the second member
which s~rews into the battery cell cover ~lid).
Figure 9 is a plan view of the first member viewed
from inside the battery. Shown is the generally flat surface ~ -
24 of the first member, the vent holes 7, and a linear rib or
protrusion 26 which protrudes inwardly about .063 inch to engage
a corresponding slot of the second member. The linear rib is
normal to an imaginary line connecting the two vent holes to
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assure that all points along the rib are no closer to either
vent hole than the center of the rib, which is about .041 inch
away. This assures that every molecule of venting gases must
travel through the narrow passage at least that distance before
being vented through the vent hole. As with the previously
described embodiments, the shortest pathway a venting molecule
can take must be at least 0.18 inch. The manner in which this
embodiment functions is similar to the embodiment of Figure 2 -
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and will be more clearly described in Figure 12.
Figure 10 is a plan view of the second member viewed
from inside the battery. Shown in a generally flat surface 27
of the second member, the threaded cylinder 23, and the afore-
mentioned slot 28 which is adapted to accept the protrusion 26
of the first member.
Figure 11 is a side view of the second member, show- ~
ing the generally flat surface 27, the slot 28, and the threaded ~ -
cylinder 23. ~
Figure 12 shows a cross-sectional view of the assembl- -
ed battery vent of Figure 8 and most clearly illustrates the
operation of the vent. Battery gases evolved from within the
cell pass into the threaded cylinder 23 and subsequently through
the slot 28. Since the slot is partially obstructed by the
protrusion 26 of the first member, the gases ~ust squeeze ;
between the slot and the protrusion in order t~ leave the threaded
cylinder cavity. The gases then pass b~tween generally flat
surfaces 24 and 27 which are forced apart by internal pressure
creating a narrow passage. The gases then exit through the -
vent holes 7, which can be raised slightly above surface 24 in
order to reduce the dhances of being plugged by grease and grime
which is likely to be deposited on top of the vent surface 24.
A gasket 29 is used to tightly seal the battery vent to the cell
opening.
It will be obvious to those skilled in the art that
many variations may be made in the embodiments chosen for
purposes of illustration without departing from the scope of the
invention.
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