Note: Descriptions are shown in the official language in which they were submitted.
CA 02366332 2001-12-31
HEAT EXCHANGER WITH INTERNAL SLOTTED MANIFOLD
BACKGROUND OF THE INVENTION
This invention relates to heat exchangers, and in particular to stacked plate
heat
exchangers using slotted manifold tubes.
Current heat exchangers for use in automobiles are well known and are
generally of the flat plate type constructed with alternating and adjacent
laterally
extending fluid flow and air flow passages. Flat plate heat exchangers that
use slotted
manifold tubes are known, including for example the heat exchangers
illustrated in U.S.
Patent No. 5,908,070 (Kato et al.) and U.S. Patent No. 6,073,686 (Park et al.)
in which
the opposite ends of flat fluid flow tubes are inserted into slots provided in
manifold
tubes. Inserted plate type heat exchangers can be cumbersome to assemble, and
be
prone to leak or otherwise fail at higher fluid pressures.
Other types of slotted manifold heat exchangers, for example as shown in U.S.
patent No. 5,560,425 (Sugawara et al.), have been proposed that use flat fluid
flow
tubes that have flanges for abutting against a portion of the manifold
adjacent a
corresponding slot in the manifold. Abutting plate type heat exchangers can
also be
cumbersome to assemble due to difficulties in maintaining manifold and plate
alignment
prior to brazing, and also may have failure concerns at higher fluid
pressures.
Still a further type of slotted manifold heat exchange is illustrated in U.S.
Patent
No. 3,605,882 (P.R. Smith et al.) in which the manifold is inserted through
holes
provided in the flat fluid flow tubes, with tube spacers being positioned on
the manifold
between adjacent flat tubes in order to secure the flat tubes in place. Such a
configuration can be complex to assemble.
Thus, there is a need for a slotted manifold heat exchanger that is easy to
assemble and that is high pressure resistant. A heat exchanger and
corresponding
assembly method that require relatively little manufacturing adjustments or
retooling to
produce heat exchangers of varying length, width or height are also desirable.
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SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided a heat exchanger
that
includes a manifold tube having a wall defining a flow passage therethrough
and having
a plurality of spaced apart openings formed through the wall in flow
communication with
the flow passageway, and a plurality of stacked flat tube elements each
including a first
plate and a second plate defining a flow channel therebetween, the plates each
being
provided with an aperture therethrough, the apertures in the first and second
plates of
each of the tube elements being substantially in alignment with each other.
The
manifold tube is received through the apertures in the first and second plates
of each of
the flat tube elements with each of the spaced apart openings in flow
communication
with the flow channel of a respective one of the flat tube elements. The wall
of the
manifold tube and the apertures are respectively sized-that an outer surface
of the
manifold tube engages an inner surface surrounding the aperture in each of the
first
and second plates to secure the flat tube elements to the manifold tube. The
openings
formed through the manifold tube wall may vary in size along a length of the
manifold
tube.
According to another aspect of the invention, there is provided a method of
assembling a stacked plate heat exchanger, including steps of (a) providing a
manifold
tube having a wall defining a flow passage therethrough and having a plurality
of
spaced apart openings formed through the wall in flow communication with the
flow
passageway; (b) providing a plurality of flat tube elements each including a
first plate
and a second plate defining a flow channel therebetween, the plates each being
provided with an aperture therethrough, the apertures in the first and second
plates of
each of the flat tube elements being substantially in alignment with each
other; (c)
positioning the manifold tube through the apertures in the first and second
plates of
each of theflat tube elements with each of the spaced apart openings in flow
communication with the flow channel of a respective one of the flat tube
elements; and
(d) radially expanding at least portions of the manifold tube such that
manifold tube
engages each of the first and second plates about the apertures thereof to
secure the
flat tube elements to the manifold tube. The heat exchanger may be brazed
after
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expansion of the manifold tube.
According to another aspect of the invention there is provided is a heat
exchanger comprising a manifold tube having a wall defining a fluid flow
passage
therethrough and a stack of flat tube elements connected to the manifold tube
and each
having a flow channel threrethrough in fluid communication with the fluid flow
passage.
A baffle cup having a wall engages an inner surface of the manifold tube wall,
the
manifold tube wall having an error proofing hole formed threrethrough at a
location
where the baffle cup wall is positioned, the hole being sized such that a
visual check
can be performed to ensure that the baffle cup is in place. The error proofing
hole is
sealably covered by the wall of the baffle cup.
According to still another aspect of the invention, there is provided a heat
exchanger comprising a manifold tube having a wall defining a fluid flow
passage
therethrough, a stack of flat tube elements connected to the manifold tube and
each
having a flow channel threrethrough in flow communication with the fluid flow
passage,
and a port fixture having a collar providing an annular flow way surrounding
an annular
area of the manifold tube wall having a plurality of radially spaced openings
formed
therethrough. The annular flow way is in flow communication with the fluid
flow passage
through the radially spaced openings, the port fixture having a connecting
member
extending from the collar and defining a fluid passageway in flow
communication with
the annular flow way.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
Figure 1 is an elevational view of a preferred embodiment of a flat plate heat
exchanger according to the present invention;
Figure 2 is a perspective view of the heat exchanger of Figure 1;
Figure 3 is a partial sectional perspective view of the heat exchanger of
Figure 1;
Figure 3A is a partial sectional elevational view showing an inlet port
mounted to
a manifold tube of the heat exchanger;
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Figure 4 is a plan view of a plate pair tube element of the heat exchanger of
Figure 1;
Figure 5 is an exploded elevational view of a plate pair tube element;
Figure 6 is a perspective view of a turbulizer of the plate pair tube element;
Figure 7 is an elevational view of a manifold tube of the heat exchanger;
Figure 8 is a plan view of the manifold tube;
Figure 9 is a perspective view of a bracket for the heat exchanger according
to
one embodiment of the invention;
Figure 10 is a schematic illustration of an assembly process for the heat
exchanger;
Figure 11 is a partial sectional perspective view of the heat exchanger of
Figure
1, showing a hydraulic bladder being used to expand a manifold tube;
Figures 12A and 12B illustrate, in elevational view, the use of a tapered pin
mandrel to expand a manifold tube;
Figure 13 is a partial elevational view showing a manifold tube having slot
openings in accordance with a further embodiment of the invention;
Figure 14 is a partial elevational view showing a manifold tube having slot
openings in accordance with still a further embodiment of the invention;
Figure 15 is a partial elevational view showing a flat tube element mounted on
a
manifold tube in accordance with a further embodiment of the invention;
Figure 16 is a partial elevational view showing a manifold tube having slot
openings in accordance with a further embodiment of the invention;
Figure 17 is a simplified elevational view showing a further embodiment of a
heat
exchanger in which a baffle cup is used to separate the manifold tubes;
Figure 18 is a sectional perspective view of a baffle cup;
Figure 19 is a partial elevational view showing an error proofing hole for the
baffle cup;
Figure 20 is a simplified elevational view of yet a further embodiment of a
heat
exchanger according to the present invention;
Figure 21 is a plan view of the heat exchanger of Figure 20;
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Figure 22 is a partial sectional perspective view of a heat exchanger
according to
another embodiment of the invention;
Figure 23 is a plan view of a bracket of the heat exchanger of Figure 22;
Figure 24 is a plan view of a further bracket configuration;
Figure 25 is a plan view of yet a further bracket configuration;
Figure 26 is a sectional plan view of a further port fitting mounted on a tube
manifold;
Figure 27 is an elevational view of the further port fitting;
Figure 28 is an elevational view of yet another port fitting;
Figures 29 and 30 are partial sectional perspective views of further flat tube
element embodiments; and
Figure 31 is a elevational view of still a further embodiment of a heat
exchanger
according to the present invention.
ZS DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The structure, operation, and method of assembly of the heat exchanger of the
subject invention will now be described, with like reference numerals used
throughout to
refer to similar parts of different embodiments of the heat exchanger.
Referring to Figures 1, 2 and 3, a flat plate heat exchanger according to one
preferred embodiment of the present is shown generally by reference numeral
10. The
heat exchanger 10 is a single pass heat exchanger which may be used in an
automotive application such as a transmission oil cooler or power steering
fluid cooler,
however the features of the present invention can be applied to a wide range
of heat
exchangers for different applications and the heat exchanger 10 of Figure 1 is
provided
as just one example of a heat exchanger according to the present invention.
The heat
exchanger 10 includes a first manifold tube 12 and second manifold tube 14,
which in
the single pass configuration illustrated function as an intake manifold tube
and an out
take manifold tube respectively. A plurality of elongate flat tube elements 16
are
arranged in parallel fashion on the manifold tubes 12,14. The flat tube
elements 16
each include a first plate 18 and a second plate 20 sealed together to form a
flow
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passage way 21 there between. Air passages 22 are located between adjacent
flat
tube elements 16, and corrugated fins 24 are located in air passages 22, fins
24 being
in thermal contact with adjacent flat tube elements 16 for providing a high
surface area
for heat exchange between the fins 24 and air flowing through the air passages
22.
As best seen in Figure 3, the manifold tube 12 includes a series of slots 42
that
are longitudinally spaced along and extend through the cylindrical wall of the
manifold
tube 12. The slots 42 are arranged so that their length runs transverse to the
longitudinal axis of the manifold tube 12. The flat tube elements 16 are each
arranged
along the manifold 12 so that each of the tube elements 16 is aligned with a
respective
one of the tube slots 42, and more particularly, so that the fluid passage 21
provided
through each of the tube elements 16 is in flow communication with the passage
30
provided through the manifold tube 12 through the respective openings provided
by
manifold tube slots 42.
Similar slots are provided along the cylindrical wall of the out take manifold
tube
14, and the out take ends of the flat tube elements 16 are arranged on the out
take
manifold 14 such that an out take end of each of the fluid passages 21
provided
through the flat plate tube elements 16 communicates with the flow passage 34
provided through the out take manifold tube 14 by way of the slots provided
along the
out take manifold tube 14.
A fluid inlet port 26 is provided on the intake manifold tube 12 and a fluid
outlet
port 28 is provided on the out take manifold tube 14. The inlet and outlet
ports 26, 28
are shown in arbitrary locations along their respective manifold tubes in
Figures 1 to 3.
The inlet port 26 defines a passage that is in flow communication with a fluid
flow
passage 30 provided through the interior of intake manifold tube 12 such that
a fluid
can flow through the inlet port 26 into the interior of the manifold tube 12
as illustrated
by arrow 32 in Figure 3. Similarly, the outlet port 28 defines a flow passage
in
communication with a flow passage 34 defined by an interior surface of the out
take
manifold tube 14. In the illustrated embodiment, end plates 36 and 38 without
flow
passages there through are provided as the first and last plate on the heat
exchanger
10.
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End caps 40, which are shown in exploded view in Figures 1 and 2, can
conveniently be used to seal the ends of the intake and out take manifold
tubes 12, 14.
Brackets 43 may be positioned along the manifold tubes 12, 14 to permit the
heat
exchanger 10 to be secured in position.
Thus, during operation of the heat exchanger 10, the fluid to be cooled enters
the heat exchanger 10 through the inlet port 26 and flows into the passage 30
in the
intake manifold tube 12. From the intake manifold tube 12, the fluid is
dispersed
through slots 42 into the plurality of fluid passages 21 that are provided
through the flat
tube elements 16. The fluid exits the fluid passages 21 through corresponding
slots
provided on the out take manifold tube 14 to enter the fluid passage 34
provided by the
out take manifold tube 14. As the fluid travels across the heat exchanger 10
through
the fluid passages 21, its heat energy is drawn off by corrugated fins 24,
which in turn
are cooled by air flowing through the air passages 22. The cooled fluid leaves
the out
take manifold tube 14 through the outlet port 28.
An overview of the heat exchanger 10 having been provided, the details of the
structure and fabrication of the elements of the heat exchanger 10 will now be
discussed in greater detail with reference to the Figures.
As can be seen in Figures 1-3, the flat tube elements 16 each include openings
at their opposite ends through which the manifold tubes 12 and 14 are
internally
received. With reference to Figures 4 and 5, which show a top plan view and an
exploded elevational view, respectively, of a preferred embodiment of one of
the flat
tube elements 16, each of the first and second plates 18,20 includes a
elongate
substantially planar central portion 56. Inwardly offset flanges 58 are
located along the
longitudinal edges of the plates 18 and 20, forming longitudinal peripheral
edges. End
flanges 60 extend between the ends of longitudinal flanges 58, thus forming
end edges
on the plates 18, 20. When the plate pairs 18 and 20 are joined together, the
offset
longitudinal flanges 56 of one plate abut against the longitudinal flanges of
the other
plate, and similarly the end flanges 60 of plate abut against the end flanges
60 of the
other plate. As will be explained in greater detail below, in one preferred
embodiment
the first and second plates 18, 20 are sealably connected along the
longitudinal edges
CA 02366332 2001-12-31
and end edges thereof through a brazing process. In some embodiments,
soldering or
adhesive bonding could be used.
The longitudinal flow passage 21 is defined between the central planar
portions
58 of the first and second plates 18, 20. A turbulizer or turbulator 62 is, in
a preferred
embodiment, located within the fluid channel 21 that is formed between the
planar
portions 56. Greater detail of one possible turbulizer 62 configuration is
shown in
Figure 6. The turbulizer 62 includes a series of undulations or convolutions
formed
therein to create turbulence in the fluid flow and in this way increase heat
transfer in the
heat exchanger. In some embodiments, turbulizers may not be used, or could be
replaced by dimples, ribs or ripples formed on the plates 18,20.
With reference to Figure 4, an opening 44 is provided through one end of the
flat
tube element 16 for receiving the intake manifold tube 12, and a second spaced-
apart
opening 46 is located at the other end of the flat tube element 16 for
receiving the out
take manifold tube 14. With reference to Figure 5, the opening 44 is provided
by
aligned apertures 48 that are pierced through the first and second plates 18,
20, and
similarly, opening 46 is provided by aligned apertures 50 that are pierced
through
opposite ends of the plates 18, 20. The apertures 48 and 50 are pierced
through end
portions of the outwardly offset planar portions 56 such that when the flat
tube elements
are assembled, the openings 44 and 46 are both in flow communication with the
fluid
passage 21 that is defined between the plates 18, 20. As best seen in Figure
3A and 4,
the apertures 44,46 are, in a preferred embodiment, arranged such that an
annular
portion 23 of the flow channel 21 extends around the circumferences of the
manifold
tubes.
A peripheral flange 64 defines an inner circumference of each of the apertures
48. The flange 64 extends outward (ie away from the flow channel) from the
outer
surface of the central planer portion 56. The peripheral flanges 64 are
integrally
formed on their respective plates, and provide an overlap joint between the
flat tube
elements 16 and the respective manifold tubes 12,14, as can best be seen in
Figure
3A.
In a preferred embodiment, the plates 18, 20, are roll formed to form the
central
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CA 02366332 2001-12-31
planar portion 56 and longitudinal flanges 58, after which the roll formed raw
plate is
lanced at a desired length and peripheral end flanges 60 are end formed. The
apertures 48 and 50 are formed by piercing and subsequently extruding the
peripheral
flange 64. As shown in Figure 4, the longitudinal flanges 58 can extend
further into the
centre of the plates 18, 20 near the apertures 48, 50 to form shoulders 59 to
abut
against each other to support the plates 18,20 near the openings 44,46, but
still provide
the annular flow path 23 around the outer facing portions of the manifold
tubes.
Shoulders 59 provide increased strength around the apertures 48,50.
The use of roll formed plates conveniently allows plates of varying lengths to
be
l0 made with minimal assembly line changes required. Plates 18,20 could also
be formed
using other techniques, including for example, stamping, however such
alternatives
may not be as flexible as roll forming for permitting changes in plate length.
Figure 7 shows an elevational view of a preferred embodiment of the intake
manifold tube 12, which is basically a cylindrical wall having manifold tube
slots 42
spaced along a length thereof. In one preferred embodiment, an inlet opening
68 is
provided for the inlet port 26. An outwardly extending flange 70, which in the
illustrated
embodiment is annular, is optionally provided at one end of the manifold tube
12 in
order to provide a stop for the end plate 36 or 38 during assembly of the heat
exchanger. The slots 42 are preferably formed by using a die punch with
internal die
support, or a saw, however it would be appreciated that other slot forming
methods
could be used, for example, saw cutting, milling, piercing, laser cutting, or
lancing.
With reference to Figure 8, an outer diameter of the manifold tube 12 is
illustrated as having a dimension D1. Prior to assembly of the heat exchanger
10, the
outer diameter D1 is less than an inner diameter D2 (see Figure 4) of the
opening 44
through the plate pair 16, in order to allow the plate pair 16 to be slidably
mounted on
the manifold 12. The out take manifold tube 14 is basically identical to the
intake
manifold tube 12, and has an outer diameter D1 that, prior to assembly, is
less than an
inner diameter D2 of the opening 46 through each of the flat tube element 16
so that
the plate pair elements can be mounted thereon.
With reference to Figure 3A, in a preferred embodiment, the inlet port 26
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includes a cylindrical collar 98 through which the intake manifold tube 12 can
pass. A
cylindrical connecting wall 100 defining an inlet passage extends transversely
from the
collar 98. Conveniently, the collar 98 can be supported by the peripheral
flanges 64 of
opposing flat tube elements as illustrated in Figure 3A in such a manner that
it can be
pivoted to a desired position during heat exchanger assembly prior to manifold
tube
expansion. In the illustrated embodiment of Figures 1 to 3, the outlet port 28
is identical
to and mounted in the same manner as the inlet port 26.
Figure 9 shows in greater detail a mounting bracket 43 according to one
embodiment of the invention for use on the intake or out take manifold tube
12,14 side
of the heat exchanger 10. Each mounting bracket 43 has first clip part 146
including
spaced-apart C-shaped clips 148, 149, each of which defines respective
contacting
surfaces 150, and a central portion or spacer member 152 extends between and
connects the clips 148,149. A second clip part 154, has spaced apart C-shaped
clips
156,157. Each clip 156,157 defines a respective contacting surface 158. A
central
portion or spacer member 160 extends between and connects the clips 156,157.
The
C-shaped clips 148, 149 are dimensioned to receive one flat tube element 16,
and the
C-shaped clips 156, 157 a second flat tube element 16. Preferably, the C-
shaped clips
are dimensioned to frictionally engage their respective flat tube element with
sufficient
force to hold the bracket in place until brazing occurs.
The inlet and outlet ports 26, 28 and brackets 43 as described above are only
one example of several different inlet and outlet port and bracket
configurations that
can be used with the present invention, and examples of further alternatives
will be
provided further below. Alternative manifold tube and flat tube element
configurations to
those described above can be used as well, and examples of further
alternatives will
also be provided below. But first, a description of the elements of a
preferred
embodiment of the heat exchanger 10 having been provided, assembly of the
elements
to form the heat exchanger 10 will now be described.
With reference to the schematic flowchart of Figure 10, as indicated by brace
92,
in one preferred assembly method a core heat exchanger stack (indicated by
reference
numeral 108 in Figure 11 ) is assembled from end plates 36,38, first and
second plates
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16, 18, turbulizers 62 and fins 24. In particular, the end plate 38 is
positioned (step 90-
1 ) and a fin 24 placed along it (step 90-2), after which a first plate 16 is
added (step90-
3), followed by a turbulizer 62 (step 90-4), followed by a second plate 18
(step 90-5)
such that the first and second plates 16,18 define fluid flow channel 21
therebetween in
which the turbulizer 62 is positioned. As indicated in Figure 10 by line 94,
building up
the core stack through the method sequence of adding a fin 24, a first plate
16, a
turbulizer, and a second plate 18 continues until the core stack reaches a
predetermined height ( which, in the example shown in Figures 1-3, includes
five plate
pairs), after which a final fin 24 is added and the core stack topped off with
end plate 36
(step 90-6). As the core stack 108 is being assembled, all the core stack
components
are aligned as illustrated in Figures 1 to 3, with plate apertures 48
substantially aligned
and plate apertures 50 substantially aligned. End plates 38 and 36 also have
corresponding apertures provided there through.
Preferably, fittings , namely the inlet and outlet ports 26,28 and brackets 43
are
then positioned on the core stack 108 as required (step 90-7). Once the
fittings and
brackets are added to the core stack, the manifold tubes 12 and 14 are
slidably inserted
through the corresponding aligned apertures in the assembled core stack (step
90-8).
The annular flanges 70 on the ends of the manifold tubes 12 and 14 act as stop
members to assist in positioning the manifold tubes. Preferably, the core
stack 108 is
then compressed (step 90-9) until the slots 42 in the manifold tubes 12 and 14
are each
aligned with a respective flow channel 21 through a corresponding flat tube
element 16.
The manifold tubes 12 and 14 are each then internally expanded to increase
their respective outer circumferences so that they each securely engage an
inner
circumference of the apertures 48 and 50, respectively, of each of the plates
18 and 20
thereby effectively locking the plate pairs16 in place (step 90-10). As
mentioned above,
prior to expansion, the manifold tubes 12 and 14 each have a respective outer
diameter
D1 (Figure 8) that is less that an inner diameter D2 (Figure 4) of the
corresponding
plate apertures 48 and 50, in order to facilitate assembly of the heat
exchanger. During
expansion, at least the portions of the manifold tube walls adjacent the plate
apertures
48 and 50 are enlarged such that the enlarged diameter exceeds the inner
diameter D2
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of the apertures. Thus after expansion, the enlarged manifold tubes 12 and 14
each
engage substantially the entire circumference of the plate apertures 48 and
50,
respectively (in the preferred embodiment that is shown in the drawings, an
overlap
joint is formed between each of annular flange 64 and the manifold tubes that
it
surrounds), preventing any further movement of the plates 16,18 relative to
the
enlarged manifold tubes 12 and 14.
With reference to Figure 11, in one preferred embodiment a hydraulic bladder
102 is placed inside each of the manifold tubes 12 and 14, and expanded by
pumping
hydraulic fluid through an inlet 106 to radially enlarge the manifold tubes in
a
substantially uniform manner along their entire lengths through radial
pressure applied
uniformly throughout the manifold tubes in the direction indicated by arrows
104. The
use of a uniform radial pressure along the length of the manifold tubes
decreases any
axial loading during the expansion process. Axial loading is generally not
desired,
especially in longer manifold tubes, as it can result in deformation that is
exacerbated
by the slotted nature of the manifold tubes.
It will be appreciated that alternative expansion methods can also be used.
For
example, in shorter manifold tubes where axial loading is not as great a
concern, a
tapered pin mandrel can be used to expand the manifold tubes. Figures 12A and
12B
show pre-expansion and post-expansion, respectively, views illustrating the
use of a
stepped tapered pin mandrel 106 to radially expand the manifold tube 14 in the
vicinity
of each of the slots 42 to achieve locally pronounced expansion at the points
along the
manifold tube 14 where the flat tube elements (not shown in Figures 12A and
12B) are
engaged by the manifold tube. If desired, in embodiments in which a hydraulic
bladder
is used to effect expansion, bands could be provided around the bladder to
localize
expansion at the points along the manifold tubes in the manner shown in Figure
12B.
With reference again to Figure 10, subsequent to manifold tube expansion, end
caps 40 are placed on the manifold tubes 12 and 14, for example by a swage or
press-
fit operation (step 90-11 ), after which the entire heat exchanger 10 assembly
is sent to
a brazing oven (step 90-12). At least the first and second plates 18, 20 of
the heat
exchanger are preferably braze clad such that in the brazing oven, the flat
tube
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elements are sealaby brazed along their respective edges, the peripheral
flanges 64
about the plate apertures 48, 50 are sealably brazed about their entire
circumferences
to the manifold tubes 12,14, repectively, the end caps 40 are sealably brazed
in place,
and the fins 24 and end plates 36,38 are all secured by brazing.
Compression of the core stack 108 (step 90-9) prior to radial expansion of the
manifold tubes is performed in the preferred assembly method to compensate for
shrinkage of the core stack that occurs during brazing. In some heat exchanger
configurations, if the flat tube elements are locked in place by expansion of
the manifold
tubes without pre-compression of the core stack, then the centre area of the
core stack
may bow inwards due to shrinkage in the brazing oven. Preferably, compression
of the
core stack is applied preferentially to the core plate stack 108 in the areas
closer to the
manifold tubes 12,14, where the greatest resistance to compression will
generally be
experienced.
The core plate stack 108 could be assembled using methods differing from that
shown in Figure 10. For example, in an alternative preferred embodiment, the
manifold
tubes 12,14 are loaded into a fixture, and the core plate stack 108 built up
by sliding the
plates onto the manifold tubes one at a time, or in groups, along with
alternating fins
and turbulizers, rather than assembling the entire core plate stack 108 and
then
inserting the manifold tubes as described above in respect of Figure 10.
The configuration of the present invention provides a heat exchanger with a
relatively high burst strength as the slotted manifold tubes 12,14 are
supported
internally within the apertures of each of the plates 18,20. Such
configuration also
provides a relatively strong joint between each of the flat tube elements and
each of the
manifold tubes. Assembly is uncomplicated as the use of expanded manifold
tubes to
secure the plates 18,20 in place prior to brazing reduces the need for any
additional
spacers or collars to be mounted on the manifold tubes to hold the plates in
position.
With relatively few assembly line changes, the heat exchanger configuration
and
assembly method of the present invention can be used to produce a number of
variations of the heat exchanger. For example, heat exchangers of different
heights
can be produced by using longer or shorter manifold tubes (for taller and
shorter heat
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exchangers, respectively) and a corresponding increased or decreased number of
flat
tube elements and fins. Heat exchangers of different lengths (as measured from
manifold tube to manifold tube in the illustrated embodiment) can be produced
by roll
forming longer or shorter first and second plates 18, 20, and longer or
shorter end
plates 36,38, and using longer or length-wise shorter fins 24. Heat exchangers
of
different widths can be produced by roll forming wider or narrower first and
second
plates 18, 20, and wider and narrower end plates 36,38, and using wider or
narrower
fins. If desired, larger or smaller diameter tube manifolds can be used with
corresponding changes being made to the apertures pierced through the plates
18,20.
The spacing between flat tube elements 16 can be changed by changing the
spacing of
the manifold slots 42 along the tube manifolds 12,14, and using higher or
lower fins 24.
it will thus be appreciated that features of the present invention can be used
in the
production of heat exchangers having varied length, width and height, without
significant assembly line tooling changes.
The present invention also provides flexibility in fitting and bracket
placement.
The location of inlet and outlet ports 26, 28, can be varied relatively easily
by using
manifold tubes with inlet and outlet openings 68 in a different location, and
then adding
the inlet and/ or outlet ports 26, 28 to the core stack 108 at a location
corresponding to
the different inlet and/or outlet openings. In practice the positions of the
fittings in this
invention can easily be adjusted to suit heat exchanger flow distribution
constraints or to
correspond to preferred fluid supply connector locations. One or both of the
manifold
tubes 12,14 could also be configured without side inlets or outlets, and
instead have an
inlet or outlet, respectively, at a manifold tube end rather than an end cap
40.
Some examples of alternative preferred embodiments of the present invention
will now be described.
It will be appreciated that in some embodiments, the slots 42 may be replaced
by
openings of a different configuration, for example circular or oval, or each
individual slot
42 could be replaced with a plurality of openings. By way of example, Figure
13 shows
a manifold tube 14 having radial rows of circular openings 172 and radial rows
of
square openings 174 in place of slots 42. Such openings may be radially
located about
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CA 02366332 2001-12-31
part of or the entire circumference of the manifold tube.
In a further preferred embodiment of the invention, the sizes of the slots 42
along
one or both of the manifold tubes 12, 14 are varied along the length thereof.
For
example, with reference to Figure 14, in such further preferred embodiment,
the
opening defined by the slot 42 designated by S2 is larger than the opening
defined by
the slot 42 designated by S1. The larger size of slot 42-S2 may be the result
of slot 42-
S2 having a greater height than slot 42-S1 (slot height being parallel to the
longitudinal
axis of the manifold tube 14), or may be the result of slot 42-S2 having a
greater length
than slot 42-S1 ( slot length being transverse to the longitudinal axis of the
manifold
tube), or may be a result of both of these factors. In embodiments where a
plurality of
openings are used in the place of a single slot, the same effect can be
achieved by
using more openings to communicate with the flow channels of flat tube
elements
where a larger opening area is desired. Varying the size of the slot openings
along the
manifold tubes may be used to improve flow distribution through the heat
exchanger 10.
In the embodiment of Figure 14, the slot openings become progressively larger
from the
bottom to the top of the manifold tube 14. In some embodiments, the slots may
be
grouped with slot size increasing progressively for groups of slots, with for
example a
group of three longitudinally adjacent slots having the same size, and then
the next
three slots having a different size and so on. The size of the respective slot
openings
through the intake and out take manifold tubes 12, 14 in flow communication
with the
inside channel through a given flat tube element 16 need not be identical in
all
applications, however slot to slot centre spacing on the two manifold tubes
should be
substantially identical to maintain proper plate pair spacing throughout the
core stack
108.
The height of slots 42 is limited to less that the distance between the plates
18
and 20. Larger slot heights can be used if the spacing between the plates 18
and 20 is
increased in the area around the manifold tubes. By way of example, Figure 15
shows
an embodiment of the invention in which the spacing between first and second
plates
18 and 20 of tube element 16 is increased in an annular area 110 surrounding
the
manifold tube 14 to accommodate a slot 42 having a height greater than the
flow
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CA 02366332 2001-12-31
channel defined by planar portions 56.
The slots 42 along the manifold tubes 12,14 may, in some embodiments of the
present invention, be directed in some other manner than inward towards the
centre of
the heat exchanger. For example, Figure 16 shows an out take tube manifold 14
in
which the slots 42 face the ends 60 of the plates making up flat tube elements
16,
rather than facing towards the centre of the heat exchanger. Such a
configuration
forces the fluid flowing through the flat tube elements 16 into the ends of
such
elements.
In some embodiments of the invention, spacing of the slots 42, and the
corresponding spacing of the flat tube elements 16 may be varied along the
length of
the manifold. For example, with reference to Figure 7, spacing H1 could be
different
than spacing H2.
Another embodiment of a heat exchanger according to the present invention is
shown in a simplified view indicated by reference number 111 in Figure 17. The
heat
exchanger 111 is similar in construction and operation to the heat exchanger
10 as
described above except for the differences noted below. As with heat exchanger
10, the
heat exchanger 111 includes a stack of alternating fins 24 and flat tube
elements 16
that extend between a first manifold tube 12' and a second manifold tube 14'.
The
manifold tubes 12' and 14' each have spaced apart slots along their respective
lengths
that connect flow passages inside the manifold tubes 12' and 14' with flow
channels in
the flat tube elements 16. However, cup baffles 112 are sealably secured
inside each of
the manifold tubes 12' and 14', effectively turning the heat exchanger into
two separate
heat exchangers, as identified by reference numbers 114 and 116, for two
different
fluids. In the illustrated embodiment of the heat exchanger 111, as indicated
by arrow
118, a first fluid flows into the portion of the manifold tube 12 ' above the
cup baffle 112.
The first fluid then flows through slots in the upper portion of manifold tube
12', through
corresponding plate pair flow tubes 16, and subsequently into the out take
manifold
tube 14', and then out of the manifold tube 14' as indicated by arrow 120. As
indicated
by arrow 122, a second fluid flows into the portion of the manifold tube 12'
below the
cup baffle 112. The second fluid then flows through slots in the lower portion
of
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CA 02366332 2001-12-31
manifold tube 12', through corresponding plate pair flow tubes 16, and
subsequently
into the out take manifold tube 14', and then out of the manifold tube 14' as
indicated by
arrow 124. In such embodiment, the first and second fluids are kept separated
in the
heat exchanger 111. Various features could be varied between the two sub-heat
exchangers 114, 116 depending on the desired treatment for the first and
second fluids.
For example, higher flat tube element 16 spacing could be used for one sub-
heat
exchanger than the other and/or larger manifold slots could be used in one sub-
heat
exchanger than in the other.
In some configurations a baffle cup 112 having a calibrated opening
therethrough may be located in either one or both of the intake or out take
manifold
tubes 12' and 14' to control fluid flow therein. In some embodiments, baffle
cups may
divide only one of the manifold tubes 12', 14', and only a single fluid be
used in the
heart exchanger, which then assumes a double pass configuration. For example,
a
baffle cup 112 could be used only in the first manifold tube 12' to divide it
in two
chambers as indicated in Figure 17, the baffle cup 112 in second manifold tube
14'
omitted, and the second manifold tube 14' capped with no outlet or inlet ports
provided
therein. In such configuration, fluid would flow into the portion of first
manifold tube 12'
above the baffle cup 112 as indicated by arrow 118, through the upper three
flat tube
elements 16 shown in Figure 17 and into the second manifold tube 14', then
into the
three lower flat tube elements 16, and back into the first manifold tube 12'
below the
baffle cup 112, and out of the manifold tube 12' in the opposite direction of
arrow 122.
From this example, it will be appreciated that further baffle cups could be
used to
configure the heat exchanger as a multi-pass exchanger.
The baffle cups 112 can each be stamped from a brazing sheet, and will
typically
2S be installed after manifold tube expansion has been carried out. An example
of one
possible configuration of a baffle cup 112 is shown in greater detail in
Figure 18, in
which the baffle cup 112 includes a circular disc like member 113 having an
cylindrical
wall 115 formed about its outer peripheral edge. Wall 115 provides an overlap
joint with
the wall of the manifold tube 12' or 14' in which the baffle cup 112 is
inserted.
Preferably the baffle cup is sized so that the circumference of the outer
surface of wall
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CA 02366332 2001-12-31
115 is small enough to slidably fit into the expanded manifold tube 12' or
14', but large
enough to frictionally engage the inner surface of the wall of the manifold
tube 12' or 14'
so that the baffle cup 112 does not move unintentionally prior to brazing once
positioned in place. In one embodiment, the baffle cup 113 is inserted into
its respective
manifold tube using a rod fixture of calibrated length to correctly position
the baffle cup.
In a preferred embodiment of the invention, an error proofing hole 117 is
provided
through the wall of the manifold tubes 12', 14' in alignment with the location
where the
baffle cup 12 should be positioned once installed. As seen in Figure 19, the
error
proofing hole 117 is positioned to align with and be covered by the baffle cup
wall 115
when the baffle cup is mounted in the manifold tube 12', 14'. The error
proofing hole
117 provides for a visual check to ensure the baffle cup is in place as an
operator can
look into the hole to ensure that it is blocked by wall 115. The error
proofing hole 117
also provides a functional check as a test fluid fed into the manifold tube
will leak out of
the hole if the baffle cup 112 is not sealably in place. It will be
appreciated that the
baffle 112 and error proofing hole 117 combination could be used for flat
plate tube
heat exchanger configurations other than the expanded manifold tube
configuration of
the present invention.
The heat exchanger of the present invention could be divided into separate sub-
heat exchangers using configurations other than the baffle cup divided
configuration
shown in Figure 17. In this regard, Figures 20 and 21 illustrate yet another
embodiment
of a heat exchanger 126 of the present invention. The heat exchanger 126 is
similar to
the heat exchanger 10 described above, except for the differences noted below.
Like
the heat exchanger 10, the heat exchanger 126 includes a stack of alternating
flat tube
elements 16(1 )-16(4) and fins 24. However, the heat exchanger includes a pair
of
intake manifold tubes 12A and 12B, and a pair of out take manifold tubes 14A
and 14B.
As illustrated in Figure 21, the manifold tubes 12A,12B, 14A and 14B are each
internally received through openings provided through each of the flat tube
elements
16(1 )-16(4). The intake manifold tubes 12A and 12B are slotted so that
neither intake
manifold tube is in flow communication with the same flow channel 21 through
the
same flat tube element, and similarly the out take manifold tubes 14A and 14B
are
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CA 02366332 2001-12-31
slotted so that neither out take manifold tube is in flow communication with
the same
flow channel 21 through the same flat tube element. For example, in the
illustrated
embodiment, the first intake manifold 12A receives a first fluid through an
inlet port as
indicated by arrow 128. The first intake manifold 12A has slots in
communication with
the flow channels through flat tube elements 16(1 ) and 16(3), but does not
include slots
along the portions of its length that pass through flat tube elements 16(2) or
16(4).
Similarly the first out take manifold tube 14A has slots in communication with
the flow
channels through flat tube elements 16(1 ) and 16(3), but does not include
slots along
the portions of its length that pass through flat tube elements 16(2) or
16(4), such that
the first fluid passes from the first intake tube manifold 12A through flat
tube elements
16(1 ) and 16(3) to the first out take manifold 14A, and out of the heat
exchanger
through an outlet port as indicated by arrow 134.
Each of the second intake manifold tube 12B and th.e second out take manifold
t
tube 14B have manifold slots 42 in communication with the flow channels
through flat
tube elements 16(2) and 16(4), but not with alternating flat tube elements
16(1 ) and
16(3). Thus, a second fluid can flow into the second intake manifold tube 12B
as
indicated by arrow 130, through the flat tube elements 16(2) and 16(4) into
second out
take tube manifold 14B, and then out of the heat exchanger as indicated by
arrow 132.
As best seen in Figure 21, the inner manifold tubes 12B and 14B preferably
have
smaller diameters than the outer manifold tubes 12A and 14A in order to
facilitate flow
of the first fluid by the inner manifolds as indicated by arrows 136 and 138.
Conveniently, the manifold slots 42 on the inner manifold tubes 12B and 14B
can be
outwardly directed (ie. towards the outer manifold tubes 12A and 14A) in order
to force
the second fluid to travel closer to the outer ends of the heat exchanger.
As noted above, the heat exchanger configuration of the present invention
permits different fittings and brackets to be used. In this regard, Figure 22
illustrates yet
another embodiment of a heat exchanger 178 of the present invention. The heat
exchanger 178 is similar to the heat exchanger 10 described above, except that
inlet
and outlet ports 26 and 28 are replaced by differently configured inlet and
outlet ports
182 (inlet port not shown in Figure 22), and brackets 43 have been replaced by
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CA 02366332 2001-12-31
differently configured mounting brackets 180.
The bracket 180 includes an L-shaped mounting plate 184 that is connected to a
cylindrical wall forming a closed collar 186 that is sized to receive wall of
a manifold
tube 12 or 14 therein. Figure 23 shows a plan view of the bracket 180 having
closed
collar 186. Other bracket configurations can be used in which an open snap-on
style
collar is used. For example Figure 24 shows a further bracket 188 having a
hook
shaped open collar 190 for engaging the manifold tube between two flat tube
elements,
and Figure 25 shows a bracket 192 having a Y-shaped open collar having opposed
semi-circular portions 194 for engaging the manifold tube. The hook shaped
collar 190
and collar portions 194 are preferably braze clad and appropriately
dimensioned and
sufficiently resilient so that the brackets 188, 192 can be snapped on the
manifold tube
at a desired location and will stay in place until brazing. Alternatively, the
collar 190 and
collar portions 194 could be crimped to secure them in place.
Turning again to Figure 22, as indicated above, an alternative port fitting
182 is
shown mounted to the manifold tube 14. The port fitting 182, which can
function as
either an inlet or outlet port, is shown in sectional plan view and
elevational view,
respectively, in Figures 26 and 27. Fitting 182 includes an annular collar 200
for
receiving the manifold tube 12 or 14. The collar 200 includes a cylindrical
wall 202 that
is capped on opposite ends thereof by disk-like end plates 204 and 206, each
of which
has a circular opening 208 therethrough for receiving the manifold tube 12 or
14. The
inner surfaces of the cyclindrical wall 202 and end plates 204, 206
collectively define an
internal cavity 210 through which the manifold 12 or 14 passes. The internal
cavity 210
has diameter, transverse to the longitudinal axis of tube manifold 12, 14,
that, is greater
than the diameter of the tube manifold 12, 14 such that an annular flow
passage 212 is
defined between the tube manifold 12,14 and the inner surface of wall 202. A
cylindrical
connecting member 214 extends radially from the outer surface of the collar
wall 202,
and the connecting member 214 defines an fluid flow passage 216 that is in
flow
communication, through an opening 218 provided in the wall 202, with the
annular flow
passage 212. A frustal-conical flange is provided at an extending end of the
connecting
member 216 for internally engaging a connector hose or like flow passage
connected to
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CA 02366332 2001-12-31
the connecting member 216.
The port fitting 182 is intended to be used in conjunction with a manifold
tube
12,14 having a plurality of radially spaced flow openings 222 provided
therethrough
which are each in flow communication with the annular passage 212. The port
fitting
and manifold tube combination of Figures 22, 26 and 27 permits fluid to be
forced into
or drawn from multiple locations about the radius of the manifold tube,
providing
improved flow management in some heat exchanger applications. The annular
collar
200 preferably has a height that corresponds to the spacing between two flat
tube
elements 16 so that it can fit between adjacent tube elements as shown in
Figure 22.
Figure 28 shows a further embodiment of a port fitting, indicated generally by
reference 224, that is similar to port fitting 182 except that it is a banjo-
type fitting
adapted for use at the end of a manifold tube 12,14. In such configuration, an
opening
208 for receiving the tube manifold 12 or 14 is only provided at an one end
plate (plate
204 in the Figure 28), and the other end plate (end plate 206 in Figure 28) is
sealed and
acts as a stop for engaging an end of the manifold tube 12,14. In banjo-type
fitting,
openings 22 could be spaced apart from the end of the manifold tube as shown
in
Figure 28, or could be notches formed about the radius of the bottom of the
tube.
In some embodiments where the fitting 182 is to be used between two adjacent
flat tube elements 16 that each encircle the manifold tubes, integral top
plates 204 and
206 may be omitted from the collar 200, and functionally replaced by the
facing
surfaces of the two adjacent flat tube elements 16.
It will be appreciated that the collar fitting and manifold tube combination
of
Figures 26 and 27 could be used in heat exchangers having a variety of
different
configurations, including for example conventional stacked plate exchangers in
which
the plate ends are received within the manifold tubes.
The flat tube elements 16 have been described as comprising two separate
opposing plates 18, 20 that are joined together by brazing along their
respective edges.
It will be appreciated that flat tube elements in which the opposing plates
are formed in
another manner can be used in the present invention. By way of example,
Figures 29
and 30 illustrate partial sectional perspective views of two further flat tube
elements 16A
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CA 02366332 2001-12-31
and 16B, respectively, each of which defines a flow channel 21. The first and
second
plates 18 and 20 of flat tube element 16A are preferably roll formed
longitudinally
together as a single sheet with longitudinal flanges 252 and 254 provided
along
opposite side edges thereof. Apertures 48, 50 for the manifold tubes (not
shown in
Figure 21 ) are then pierced through each of the plates 18, 20, and the flange
about the
apertures extruded, after which the plates 18, 20 are folded together about a
common
longitudinal edge 250 until the flanges 252 and 254 contact each other. With
respect to
the flat tube element 16B, in such configuration the edges 256, 258 joining
the first and
second plates 18, 20 are seamless.
Although the heat exchanger 10 has been shown in its preferred embodiment as
including a flange 64 about the apertures 48, 50 in first and second plates
18, 20, in
some applications a flangeless aperture may sufffice, in which case a somewhat
weaker butt joint rather than an overlap joint would be formed between the
plates 18,
and each of the manifold tubes 12, 14. Furthermore, in some embodiments, the
15 annular flow path 23 may not be present about the entire circumference of
the manifold
tubes.
The heat exchangers of the present invention as described above have each
included corrugated fins 24 located between adjacent flat tube elements 16. In
some
embodiments, such fins may be omitted, or replaced with ribs or other
protrusions
20 formed on the flat tube elements 16. In embodiments where the fins are
omitted,
spacing between the adjacent flat tube elements 16 may be provided by enlarged
bosses around the apertures, such as the enlarged annular area 110 as shown in
Figure 15. In some fin-less embodiments, removable spacers may be positioned
between adjacent tube elements 16 to support them during assembly.
Another embodiment of a heat exchanger according to the present invention is
shown in a simplified view indicated by reference number 270 in Figure 31. The
heat
exchanger 270 is similar in construction and operation to the heat exchanger
10 as
described above except for the differences noted below. In heat exchanger 10,
the
manifold tubes 21 and 14 are connected by a bypass tube 272 through which
fluid can
flow directly from one manifold tube to the other, bypassing the core stack
108. A
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CA 02366332 2001-12-31
calibrated baffle 274 or other flow control means such as a thermostatically
actuated
valve can be located in the bypass tube 272 to control flow therethrough. The
tubes 12,
14, and 272 may be integrally formed as a single U-shaped unit.
In some embodiments, only a single expanded manifold tube may be used, with
the second manifold having a different configuration, such as, for example,
the cup
configuration shown in U.S. patent No. 5, 634, 518 issued June 3, 1997.
The above description has anticipated that the heat exchanger components are
made out of metal. However, other materials such as plastics or other polymers
could
be used in some applications for all or some of the heat exchanger components.
In a
polymer embodiment, manifold tubes may be thermally expanded rather than or in
addition to being pressure expanded. Alternatively, the manifold tube may not
be
expanded, but a friction fit between the flat plate tube element and the
manifold tubes
used in combination with bonding effected, for example, thermally,
ultrasonically, or
through the use a bonding agent or adhesive.
The heat exchanger of the present invention can be adapted for a number of
different applications for use, among other things, in automobiles,
recreational vehicles,
and fuel cell thermal management systems. In addition to the transmission oil
and
power steering fluid cooling applications mentioned above in respect of heat
exchanger
10, the present invention can be adapted for use in, among other things,
engine oil
cooling, hydraulic fluid cooling (which requires high pressure strength) and
air
conditioning applications (for both evaporator and condenser applications).
Selective
variable manifold tube slot size and positioning can be particularly helpful
in evaporator
applications where flow distribution sensitivity is high.
It will also be apparent to those skilled in the art that in light of the
foregoing
disclosure, many other alterations and modifications are possible in the
practice of this
invention without departing from the spirit or scope thereof. Accordingly, the
scope of
the invention is to be construed in accordance with the substance defined in
the
following claims.
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