Note: Descriptions are shown in the official language in which they were submitted.
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CC~XRO~\IBLE CONTAIN~R r~l~p~ A~r ~)?12~rrTC D ~ 0N OF
_~ _ ___ _ _ _ __ _ __ _ _ _ _ ___ _ _ _
CORROS ION I~Hï, ITOR To .~ COC\L~NT SYSTE~
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~ackground of the Invent:ion
Engine coolants for the cooling system of an auto-
motive vehicle usually contain e_hylene glycol and a
small percentage of diethylene glycol. This fiuid is
diluted with water to provide a 50% or lower concen~ ¦
tration of glycol depending on the desired freezinc3
point for the coolant system. Most companies that
manufacture and/or distribute ethylene glycol for
coolant systems add corrosion inhibitors to the solution
-to prevent corrosion of the copper-brass traditionally
used in the manufacture of vehicle radiators.
These inhibitors usually are a mixture of one or
more inorganic salts, such as phosphates, borates,
nitrates, nitrites, silicates or arsenates, and an
organic compound, such as benzotriazole, tolyltriazole
or mercaptobenzothiazole, to prevent copper corrosion.
The solution is generally buffered to a pH of 8 to 10
to reduce iron corrosion and to neutralize any glycolic
acid formed in the oxidation of ethylene glycol. Most
companies recommend a maximum of one or two years'
service for their antifreeze coolant, however, it has
been found that the a~erage car owner does not follow
the owner's instruct.ion manual to maintain -20 F.
protection for the coolant system and does not check :
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the coolant to determine if it is rusty or dirty. ~!any
owners only add water when the antifreeze is lost
through leakage or hose breakage. This is more likely
to occur in the southern part of -the country than in
northern areas.
In normal passenger car service, 25% of the cars
re~uire coolant system servicing a~ter only one year;
after two years this percentage rises to 50%. With
normal copper-brass radiators, and even more so with
aluminum systems, it is extremely important that the
antifreeze or coolant mixture contain 50 to 55~ of the
correctly inhibi~ecl ethylene glycol. A reduction to a
mixture of 33~ ethylene glycol - 67~ water will inc:rease
metal corrosion significantly. This is especially
important with higher temperature coolant systems ~thich
are becoming more common with -the increasecl use of
emission controls.
Also, with the increasing emphasis on gas mileage
of the new automobiles, cars are being downsized and
reduced in weight through the substitution of light
wei.ght metals or plastics for iron and steel where
practical. In the automotive coolant systems, aluminum
radiators are being utilized instead of the conventional
copper-brass radiators previously used. As above
noted, an aluminum radiator is more susceptible to the
corrosive action of a coolant or antifreeze that is low
in the percentage of ethylene glycol and/or where an
insufficisnt amount of corrosion inhibitor is present
in the coolant. In such a system, additional corrosion
inhibitor must be added or the aluminum will begin to
corrode by pittin~ at a rapid rate. The present invention
ameliorates this corrosion problem by providing for the
automatic addition of a corrosion inhibitor under corrosive
conditions for the coolant.
The present invention relates to a device for the
automatic addi-tion of corrosion inhibi~or when the corrosive-
ness of the engine coolant in a vehicle reaches or exceeds a
predetermined level wherein the device comprises a closed
container for the solid or liquid corrosion inhibi-tor with
at least a portion of the container formed of substantially
the same material as the heat exchanger or radiator through
which the coolant passes and exhibits its corrosive tendencies.
The container portion should not corrode in properly
inhibited ethylene glycol-water solution, however, as the
coolant becomes corrosive, the corrodible portion of the
container will corrode at a rate faster or equivalent to that
of the radiator. In a specific embodimen-t of the invention,
the corrodible material is much thinner than the radiator
material, and therefore, it would be quickly penetrated to
release the corrosion inhibitor into the coolant system.
One embodiment of the present invention also relates
to a device for releasing corrosion inhibitor into a coolant
system where a foil of the material forming the radiator
either forms a ~ortion of one end of a container or forms a
foil packet containing the corrosion inhibitor. The foil is
exposed to the coolant in the cooling system of the vehicle
by insertion in a tank of the radiator, in the overflow
reservoir for the coolant, or in a flow line leading to or from
the radiator so as to have the foil in contact with the coolant.
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In a specific embodimen-t of the present inven-tion
there is provided a device for releasing corrosion inhibitor
wherein the container is either a glass, plastic or metal
member open at one or both ends ancl having a foil of
substantially -the same material as the radiator covering the
open ends. The foil is suitably secured to the container by
an adhesive or a screw top cover having ~n opening therein.
I~ the container is metal, a small tab opening in the end
may be covered with the foil.
The present invention may also incorporate a container
for corrosion inhibitor having an opening in an end or an
open end covered with aluminum foil wherein the radiator is
formed of aluminum sheet material brazed together.
A specific embodiment oE the presen-t invent,ion also
comprehends the provision of a container for corrosion
inhibitor formed of a me-tal less corrodible than aluminum
with an aluminum end secured to -the container a]ong its
periphery and having a scored or knurled portion in the end
to provide a limited area of a reduced thickness. When the
coolant becomes corrosive, the scored area will be attacked
and corrode by pitting to a greater degree than the surrounding
metal so as to provide for an earlier penetration and release
of the corrosion inhibitor.
One embodiment of the present invention further
comprehends the provision of a container packaging the
corrosion inhi~itor to provide for a release of the inhibitor
more than once. ~ foil packet is formed with corrosion
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inhibitor sealed therein. This foil packet along with
additional inhibitor is sealed in a larger foil packet,
and this packet in turn with additional inhibitor is
sealed in a larger packet. Thus the c)uter packet would
S corrode first to release its inhibitor and the re-
maining packets would be available to give further pro-
tection at a later time. A dye could ~e added within
the innermost packet to indicate to the owner -that a
new inhibitor package is required.
Further objects of the present invention are to
provide a construction of maximum simplicity, efficiency,
economy, and ease of operation, and such further
objects, advantages and capabilities as will later more
fully appear and are inherently possessed thereby.
Description of the Drawings
One way of carrying out the invention is described
in detail below with reference to drawings which illustrate
only one specific embodiment, in which:-
Figure 1 is a perspective view of an automobile
radiator showing one method of positioning a corrosioninhi~itor container in cooperation therewith.
Figure 2 is an enlarged side elevational view
partially in cross section showing the mounting for the
container taken on the line 2-2 of Figure 1.
Figure 3 is an enlargecl partial cross sectional
view of a container for corrosion inhi~itor.
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Figure 4 is a side elevational view partially in
cross section of a second embodiment of container.
Figure 5 is a perspective view of a third embodiment
of container for corrosion inhibitor.
~igure 6 is a perspective view o:E a fourth embodiment
of container for multiple charges of inhibitor.
Figure 7 is a cross sectional view taken on the
line 7-7 of Figure 6.
Fiyure 8 is a partial perspective view of a fifth
embodiment of corrosion inhibitor container.
Figure 9 is a partial perspecti~re view of a sixth
embodiment of corrosion inhibitor contair-er.
Figure 10 is a partial cross sectional view taken
on the line 10 10 of Fiyure 9.
Figure 11 is a perspective view of a seventh embodiment
of corxosion inhibitor container.
Figure 12 is a vertical cross sectional view of
the container taken on the line 12~12 of Figure 11.
Figure 13 is a perspective view of an eighth
embodiment of inhibitor container.
Figure 14 is a vertical cross sectional view taken
on the line 14-14 of Figure 13.
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Descrip~ion or the Prererred E~bodiments
Referring more particular~y to the disclosure ln
the drawi.ngs wherein are shown illustrative embodiments
of the present invention, Figure 1 discloses an automobile
radiator 10 for the coolant system of the vehicle
engine ~not shown)O The radiator includes an inlet
tank 11 having an inlet hose 12 communicating therewith,
an ou-tlet tank 13 with an outlet hose 14 extending
therefrom, and a heat exchange core 15 including a
plurality oE tubes extending between and connecting the
inlet and outlet tanks and folded or corrugated heat
exchange fins between the tubes allowing air to pass
between the tubes but breaking the airstream up to
enhance the heat e~change characteristics of the
radia-tor. The inlet -tank is also provided wit}l an
inlet neck closed by a pressure cap 16 and a conventional
overflow tube (not shown) is connected to the lleck to
allow for overflow of the coolant in the radiator to
the overflow reservoir. The radiator may be o~ -the
downflow type as shown or o~ the crossflow type.
As seen in Fiyures 1 and 2, a T-connector 17 i~
inserted into the inlet hose 12, either by sealingly
fitting over the hose with an opening 18 in the hose
communicating with the depending leg 19 of the connector
or by inserting the connector into a break in the hose
(not shown). The depending leg 19 recelves a container
21 for a corrosion inhibitor in either solid or liquid
form and seals around the upper end 22 of the container
by screw threads 23 (see Figure 2) or by an exterior
clamp (not shown). The T-connector is equally adapted
to be located in the outlet hose 14.
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The container shown in Figures 2 and 3 is a jar 24
closed at the bottom and open at the top formed of a
suitable glass or plastlc material able to withstand
the temperature of the heated fluid and the temperatures
present wi-thin the engine compartment.. The upper end of
the jar has exterior screw ~hreads 25 for a threaded
cap 26 having a central openlng 27. A piece of metal
foil 28 is positioned over the open end of the jar 24
filled with a corrosion inhlbitor 29 and Eormed over
the threads 25. The cap 26 is screwed onto the jar to
seal the foil thereon, and one or more rubber gaskets
may be necessary in the cap to improve the seal.
The engine coolant is preferably a 50-50 mixture
of ethylene glycol and water with a corrosion inhibitor
in the ethylene glycol as supplied to the vehicle
owner. This mixture is circulated from the radiator 10
by a fluid pump through the engine block for cooling.
The coolant, heated from the engine block, is returned
to the radiator for cooling by a forced air flow
through the radi.ator core 15 around the tubes connecting
the tanks 11 and 13. As the liquid passes through the
inlet hose 12, it will contact the metal foil 28 on the
container 21. If a leak develops in the coolant
system or a hose ruptures, the owner is likely to
replace the coolant with water from any readily avail-
able source. This water obviously is not treated andis likely to be corrosive to the metal of the radiator.
As the metal foil 28 is of substantially the same
material as the radiator construction and is considerably
thinner than the material stock forming the radiator,
the corrosive water will tend to attack the foil as it
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passes through the hose 12, and the foil would tend to
corrode at the same or a faster rate than the radiator
depending on the alloy composition. When penetration
of the foil is achieved, the coolant will dissolve a
solid inhibitor and/or force the liquid inhibitor into
the coolant stream to stop or retard the corrosion of
metals in the coolant system.
For the conventional copper-brass radiator system,
a copper foil would be used to seal the jar 24. Like-
wise, if an aluminum radiator were subs~ituted for the
copper-brass one, then an aluminum foil would be used.
For the aluminum radiator, the corroslon problem :is of
utmost importance because of the faster rate of corrosion
by pitting compared to copper-brass. Tests were run
using a glass vial with aluminum foil of a thickness of
0.75 mil over the open end and a corrosion inhibitor of
either disodium hydrogen phosphate or lithium nitrate~
Tests were run at room temperature with the foil
exposed to a conventional antifreeze solution and to a
corrosive water containing 300 ppm chloride ion as
sodium chloride and 1.0 ppm copper ion. After several
days, analysis of the antifreeze showed no change for
disodium hydrogen phosphate or lithium nitrate in the
antifreeze, while the corrosive water showed a marked
increase in the concentration of the particular in-
hibitor in each case.
Figure 4 discloses a second embodiment of container
for the corrosion inhibitor using a glass or plastic
-tube 31 open at both ends, with each end covered by a
suitable metal foil 32 which is sealed at the edges 33
by bonding using a Past cure epoxy resin or gLued with
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a Pliobond (rubber base) adhesive. Other suitable
adhesives include silicones, acrylics or cyanoacrylates.
Figure 5 discloses a third embodiment of container
34 for a corrosion inhibitor which is adapted to be
positioned with the inlet -tank ll of the radiator 10 or
in the overflow tank (not shown). This container is a
packet formea from two sheets of a suitable foil 35
sealed around all four edges 36 with a predetermined
quantity of corrosion inhibitor 37 therein. The edges
are sealed with â suitable adhesive or mechanical
means, such as ultrasonic welding, could be used.
Under cyclic temperature conditions, a double sealed
aluminum foil package may be necessary. To accomplish
this, strips of foil are folded over the original
packet edges 36 and then sealed to the edges uslng a
suitable adhesive or mechanical means.
Figures 6 and 7 disclose a fourth embodiment of
container 38 adapted to provide more than one charge of
corrosion inhibitor when positioned in the radiator
tank or overflow container. This container consists of
a first foil packet 39 containing a predetermined
quantlty of corrosion inhibitor 41, a second foil
packet 42 receiving the first packet 39 therein along
with a second quantity of inhibitor 43, and a third
foil packet 44 receiving the second packet 42 along
with a third quantity of inhibitor 45. All three
packets 39,42 and 44 can be sealed along their in-
dividual edges 46 as shown in Figure 7 or all three
packets can be sealed simultaneously along common edges
(not shown~.
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With this container 38, corrosion inhibi-tor would
be released more than once as the corrosiveness oE the
coolant varies. When the container 38 is first introduced
into the ethylene glycol-water mixture, the outer foil
packet 44 would not be attacked. ~s the corrosiveness
of the coolant increased~ the outer foil packet would
corrode to release the inhibitor 45. The inner pack~ts
would remain intact to give further protection, if
needed at a later date. As the effectiveness of the
inhibitor decreased, the second foil packet 42 would
corrode releasing the inhibitor 43; and later, the
inner foil packet 39 would corrode to release the
inhibitor 41. A colored dye could be added to the
inhibitor 41 in the packet 39 to be released as a
visual signal that a new inhibitor package is needed.
Figure 8 discloses a rifth embodimen~ of container
47 to be inserted into the T-connector 17 of Figure 1.
This container consists of a steel or aluminum body 48
which is normally drawn to provide a one-piece side
wall and hottom or a separate bottom may be secured to
the side wall. A top 49 is secured to the upper end of
the body 48 by a conventional flanging operation as at
51. The metal top has an opening 52 formed therein
which may be as shown in dotted outline in Figure 8 or
the opening may be of the conventional pull-tab or "pop
top" design. A piece of foil 53 is positioned over the
opening 52 and secured around the edges by a suitable
adhesive or mechanical means. In this em~odiment7 the
foil 53 would be attacked by the corrosive li~uid to
pit and allow penetration of the liquid into the can
body 48 to contact and/or dissolve the inhi~itor and
carry it into the coolant system.
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Figures 9 and 10 disclose a sixth embodiment of
container 54 having a drawn steel or a~uminum bodY 55
to receive the corrosion lnhibitor 56 therein. The
body has an open end covered ~ith a sheet of material
57 substantially identical to the radiator material
requiring corrosion protection~ The top material 57 is
scored as at 58 or knurled to provide lines or bands of
material that are thinner than the sheet stock for -the
top and the top is secured to the body by a flange at
59. This container is also adapted to be received in
the T-connector 17 of Figure 1. When exposed to a
corrosive coolant liquid, the scored portion 58 o the
top 57 will tend to corrode or pit before the remainder
of the lid and penetration of this scored portion will
allow en-trance o~ the coolant into the con-tainer and
reIease of the corrosion inhibitor thereln.
The corrosion inhibitor release rate can be con-
trolled by the score depth and/or increased by use o~ a
galvanic couple. Also, the top 57 could be formed of a
metal alloy similar to that of the radiator but more
susceptible to corrosion.
Figures 11 and 12 disclose a seventh embodiment
of container 61 similar to the container 54 except for
several partitions 66, 67 and 68, each having a scored
or knurled portion 69. The container 61 includes a
drawn side wall 62 with an integral or attached bottom
wall 63 and a top wall 64 formed of a material sub-
stantially identical to the radiator material requiring
corrosion protection. The top wall has a knurled or
scored portion 65 which will tend to pit or corrode
before the remainder of the top wall.
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The partitions 66, 67 and 68 act to separa-te the
corrosion inhibitor into four individual portions 71, 72,
73 and 74 which will be released sequentiaLly. Thus,
with the top wall 64 of -the con~ainer 61 exposed to the
coolant flow, when the concentration of corrosion in-
hibitor decreases below a predetermined level or the
corrosiveness of the coolant increases, the scored
portion 65 will pit and corrode until penetration of
the wall allows the coolant to contact the inhlbitor
portion 71 and release the inhibitor into the coolant
stream. This cycle will repeat itself for each of the
partitions 66, 67 and 68 to retain a proper corrosion
inhibitor level o~er an ex-tended period of time.
Although shown as a single container wall 62 with
intermediate partiti.ons, the container can also be formed
as several individual containers joined together such
that the wall 62 would become four short cYlindrical
wall portions with the top wall or a partition forming
the end o each short container. ~.
~igures 13 and 14 illustrate an eighth embodiment
of container assembly similar to the foil packet assembly
of Figures 6 and 7. This assembly comprises an inner
container 75 having a cylindrical side wall 76, a
bottom wall 77 and a top wall 78 secured thereto and
filled with corrosion inhibitor 81. The top wall is
provided with a scored or knurled portion 79. An inter-
mediate container 82 having a side wall 83 r bottom wall
84 and a top wall 85 with a scored portion 86 houses the
inner container 75 and a second charge of inhibltor 87.
An outer container 88 also includes a side wall 89, bottom
wall 91 and top wall 92 with a scored portion 93; the
container housing the intermed:iate and inner containers
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75 and 82 and a third charge of inhibitor 94. This
embodiment provides a sequential additi.on of corrosion
inhibitor in sub~tantially the same manner as the
embodiment of Figures 6 and 7.
Of the various corrosion inhibitors, several
exhibit properties of expansion of the salt from the
anhydrous to the hydrated salt, which expansion in a
container with a foil covered end or ends will force
out the foil or crack the container and effect a rapid
release of the inhibitor into the coolant system. One
such salt is anhydrous disodium hydrogen phosphate.
Other such salts that expand when hydrated include
sodium acetate,-sodium metaborate, sodium tetraborate,
sodium carbonate, sodium chromate, sodium molybdate,
sodium phosphate, sodium pyrophosphate, sodium silicate
and sodium sulate. Organic polymers which are water
soluble or swellable ancl may expand when hydrated
include cellulosic products, polyacrylic acid, poly-
acrylamide and poly(ethylene oxide).
Another method of destroying the foil once it has
been weakened by corrosion is the provision of a
compressed coil or leaf spring in the container with
the inhibitor. The spring is of a strength to be
compressed when the foil is sealed onto the container
but would rip open the foil and/or push out the in--
hibitor when the foil was weakened by corrosion.
~lthough the present invention is shown and des-
cribed for controlling corrosion resistance in an
automobile coolant system, this system can be utilized
in other heat exchange systems where ethylene glycol or
similar coolant is provi.ded as the heat exchange
medium.
