Note: Descriptions are shown in the official language in which they were submitted.
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HEAT EXCHANGER
In heat exchangers of the type considered herein there
is usually provided a pair of spaced header plates between which
extend spaced tubes for conveying liquid between spaced tanks of
S which the header plates are parts. Air is then forced over and
between the tubes and usually in contact with serpentine fins
for cooling the liquid flowing through the tubes. An automotive
radiator is a good example of such an exemplary heat exchanger.
Many of these heat exchangers particularly where the
headers and tubes are constructed of brass and the
interconnecting fins of copper are deficient in strength because
the joints are customarily solder and have poor creep and
fatigue properties. This invention both in structure and method
avoids these difficulties by providing a primary load bearing
joint such as weld metal joining the tubes to the headers at
their areas of contact or of close proximity and then a thin
sealant sealing against leakage any small leakage openings such
as cracks, fi.ssures, pin holes or the like that may be present.
The most pertinent prior art of which I am aware are
the following U.S. patents: 2,270,864; 2,914,346; 3,078,551;
3,349,464; 3,496,629; 3,633,660; 3,6~9,941; 3,710,473; 3,750,747
and 3,763,536. Although many of these patents illustrate the
problems of cracks, fissures and similar leaks in welded joints,
none of them teach the solution to this problem of providing in
the heat exchanger combination a thin sealant.
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The present invention comprehends a liquid-to-air heat
exchanger. The exchanger is comprised of a header plate
containing a plurality of spaced tube receiving holes. A liquid
coolant tube extends into each hole. A primary load bearing
joint subject to the formation of leakage openings therein joins
each tube to the plate at its opening. An air side of the joint
is exposed to the air, and a thin sealant on the air side seals
against leakage in any leakage openings that may be present.
The invention further teaches a method of making a
liquid-to-air heat exchanger. The method comprises the steps of
providing a header plate containing a plurality of spaced tube
receiving holds, and inserting a liquid coolant tube into each
hole. Next a primary load bearing joint subject to the
formation of leakage openings therein is provided to join each
tube to the plate at its opening. A thin sealant on the air
side is provided to seal against leakage in any leakage openings
that may be present.
Other aspects of the invention will be appreciated
from a reference to the accompanying drawings illustrating
the preferred embodiment of the invention to be disclosed
in detail and wherein:
Figure 1 is a plan view of an automa~ive radiator
embodying the invention,
Figure 2 is a fragmentary partial perspective view
of the elements of the radiator of Figure 1.
Figure 3 is an enlarged fragmentary sectional view
taken substantially along line 3 - 3 of Figure 2.
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The radiator 10 as illustrated in Figure 1
comprises an upper tank 11, a lower tank 12 spaced
therefrom, spaced tubes 13 of oval or flattened cross
section spaced from each other with adjacent tubes
being interconnected by serpentine fins 14 having their
crests 15 attached to the tubes 13 in the customary
manner as by welding, brazing, soldering or the like.
The tanks 11 and 12 have as component parts
upper 16 and lower 17 header plates through which the
tube ends 18 extend as shown in relation to the upper
plate 16 of Figure 2. The plates 16 and 17 each are
provided with an outwardly extendin~ flange as illus~
trated at 21 in Figure 3 as a part of the lower plate 17.
These flanges 21 describe a hole 22 into which the tube
end 23 extends.
This tube end 23 is attached to the plate
flange 21 by a primary load bearing joint 24. This
joint is in two parts with the first part bein~ the
welded joint 24 and the second part being a solder
coating 25 on the air side between the tube 13 and
flange 21.
Where the heat exchanger is constructed of
metal the load bearing joint 24 is preferably of welded
construction. The term "weld" is used in its broadest
sense and is usually formed with metal parts by heatinq
; and allowing metals to flow together. Where the parts
are of plastic, and this heat exchanger can be construct-
ed of strong plastic parts, these parts are united in a
similar manner by heating to form the weld.
After the primary load bearin~ joint 24 is
formed there is added the second part of the joint:
the solder coating or layer 25.
The mair- part of the load between the headers
16 and 17 and the tubes 1~ is taken up by the primary
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load bearing joint 24. The sealant 25, particularly
where it is solder or brazing on a welded joint, also
has a load bearing function. However, its main purpose
is to seal up and close leakage openings such as fis-
sures, cracks, pin points and the like that occur eitherduring the manufacturing process or in subsequent use.
In any event, although the primary purpose of the seal-
ant 25 is to prevent immediate or after developed leak-
age problems, it does function to distribute some of the
forces between the tubes 13 and the header plates 16 and
17 and particularly those caused by internal pressure
and temperature changes of the liquid on the interior 33
of the tubes.
With the usual flattened tubes 13 of the cus-
tomary automotive radiator, and especially when thesetubes comprise brass, internal pressure changes of the
coolant, normally water, within the tubes causes the
sides 34 of the tubes to tend to expand away from each
other under internal pressure and contract back toward
each other to the position shown in Figure 2, for exam-
ple, under these internal pressure as well as temperature
changes. The primary joint 24 successfully absorbs
these loads caused by pressure and temperature expansion
and contraction.
Although this invention is most useful in con-
.junction with heat exchangers made of metal parts, it is
also useful in heat exchangers made of reinforced plas-
tic; and these are coming intO increasing use. Whether
of plastic or metal, the joint 24 is a primary load
bearing joint. The sealant 25 in all these embodiments
functions mainly as a sealant but is also, secondarily,
a load distributing member.
Having described my invention as related to
the embodiment shown in the accompanying drawings, it is
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my intention that the invention be not limited by any
of the details of description, unless otherwise speci-
fied, but rather be construed broadly within its spirit
and scope as set out in the appended claims.
