Note: Descriptions are shown in the official language in which they were submitted.
~ wn 93/0~3~4
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~ANIFOLD A88~MB~Y FOR ~ P~RAL~EL
. FLQW ~EAT EXC~ANGER
, ~
.~; B~CR~RO~ND OF THE INVENTION
~, The present invention is directed t~. the -:field of
~1 manifold assemblies for use with heat exchangers, particularly
~I heat exchangers for refrigeration applications.
j Heat exchangers for refrigeration applications,
~.~ 5 particularly condensers and evaporators, are subjected to
`, relatively high internal refrigerant pressure. Further, such
heat exchangers cannot allow any leakage of refriger~nt into
the atmosphere and therefore preferably are designed with as
:~ few manufacturing connections as possible. Where
~ 10 manufacturing connections are necessary, their joints must be
:: able to be manufactured ecvnomically and with a high
probability that they will not leak.
¦ Automotive conden~ers have typically been constructed
with a si~gle length of refrigerant tube, assembled in a
serpentine configuration with an inlet at one end and an
outlet at the other end. In some cases, two or more of such
~i ~erpentine coils are assembled into an intertwined
~j configuration so as ~to provide a multiple path flow of
;, refrigerant across~the air flow. The ends~o~ the separate
serpen ine coil8 are connected ~o common ~ani~olds. Th~is
concept of multiple path flow is~extended to what is called a
~; "parallel flow heat exchanger, 11 in which all refrigerant tub~s
are straight and p~rallel to each other with the individual
ends of these tubes ~onnected to re~pecti:ve inlet an~ outlet
`~ 25 manifolds. This configuration is: commonly utilized in the
.~ I constru::tisn of engine :cooling radiators, oil coolers, ~nd
more recently, air conditioning condensers.
`~ Condenser applica~ion to: parallel f low has beerl more
difficult to achie~e in practice because of the ~ need îor
j 30 multiple high pressure ~oints. Also, the atmospheric problems
?~. ~1 ' as~ociated with release ~ of standard refrigerants has
-, necessitated the change to newer, ~ more chlorinated
~:i refrigerants such as R-134A. The R 134A refrigerant is not as
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efficient as R-12 refrigerants, and also operates at higher
pressure than R-12 refrigerants. The lower efficiency of the
R-134A rerigerant requires a condenser design which not only
is more ef f icient, such as a parallel f low design, but also is
able to withstand higher internal operating pressures.
Manifolding multiple tubes to withs~;a~ high internal
pressure can best be accomplished with a tu3aular manifold, the
c:ross-section of which is circular for highest strength. U.S
patent No. 4, 825, 941 to Hoshino et al. is an example of such
a manifold with a circular cross-section. The chief
-.~i disadvantage to the tubular manifold with a circular cross-
section i5 the difficulty of piercing the series of holes in
~ each manifold to receive the multiple parallel refrigerant
:. tubes. Also, the tubular manifold with circular cross-section
~ 15 presents difficulties in assembly during manufacture. One
,.~
`1 partial solution to these problems is to f la~ten one side of
`' each manif old tube as shvwn :in Fig . 2, so as to provide a D-
.. ; shaped cross-section which can more easily be pierced and
; ~ subsequently assembled . However, insertion of the tubes into
.~. 20 the manifold is still di:Eficult. Also, in some heat exchanger
deSiyllS, it i5 necessary to insert baffles in each manifold to
reate a multiple pass refrigerant flow. In~ertion of the
baffles into a tubular manifold can also present difficulties
in assembly during manufacture.
~? 25 Accordirlgly, it has been proposed to use a two-piece
~; manifold comprising a tank and a header plate. In one such
,, .
.~ construction, shown in Figure 2 of ~J. S. patent No. 4, 938, 284
~ to Howells, the tank is foxmed wi~h inwardly facing grooves
.~i and the tank is slid int$: engagemellt with the header plate,
i.3 30 wh ch is planar. As shown in Figure 5 of the Howells patentl-. the tank can alternatively ~e fe)rmed with inwardly curved side
wall members and the header plate can be f ormed with upturned
longitudinal edges for gripping engagement with the side wall
.`' members of the tan)c when the tank is slid into engagement with
35 . the header plate. In both constructions, the tank is coat~d
befor~ assembly with a brazing material and flux to enable it
`~ to be secured upon assembly to the header plate.
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-, Although the constructions shown in the Howells patent
. provide both a mechanical and metallalurgical bond between the
, tank and header plate, sufficient clearance must be provided
i between the tank and the header plate to permit sliding of thP
one onto the other. This clearance prevents the good fit
required for effective braæing. Furt~, it -is ofken
.. desirable to provide baffles in the assembled tank and header
plate to adjust the flow pathO When the tank and header plate
are assembled ky sliding, it is difficult, if not impossi~le,
~.l, lO to place baffles between them prior to assembly.
'.J, In another construction, the tank is provided with a
~, flange, ta~s are placed on the header plate, a gasket is
inserted between the header plate and the tank, and the tabs
are crimped over the tank flange. Examples of s~c~ a
construction ~re shown in U.S. patent No. 4,455,728 to Hesse,
:i U.S. patent No. 4,~31,578 to Stay et al., and U.S. patent ~o.,
l 4,600,051 to Wehrman. A :Leak-type seal is provided by
compressing the gasket. However; compression of the gasket is
. nst sufficient to seal the header pIate and tank under the
high pressure~. fou~d in condensers.
''`~J ~ solution to these~problems was proposed in co-pending
i~. U.S. application serial :No. 503,798 of Calleson, which is
.,':'D ~ expreissly incorporated herein by reference. In the Calleson
appliGation~ a palr of opposed:parallel shelves are formed in
25~ ~ the inner wall of the: tank inwardly of ~he bottom edges to
define a pair of flanges extending fr:om the shel~es. The
`:i, shelves in the tank fo~m s~ops:against which the~header pla~e:
abuts. The tank flanges~ are e~imped inwardly to ~ngage at
least a porti~n o~ the edg~ portions of the header plate along
the entire length of the header platie. Also, the tank and
header plate are brazed together along substantially the
entire lengths of their~mating surfaces in order to provide
`~ both a mechanlcal and a metallurgical bond which provides th~
.~
~ strengths to withs~and hig~ internal pressures. A pair of
:i 35 opposed, longitudinally-extending horizontal ribs can be
formed in the inner wall~of the tank and provided with opposed
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slots to receive baffles, in order to adjust the flow pattern.
The horizontal ribs can also serve as tube stops.
Although the crimped flange proposed in the Calleson
~` application is superior to the prior art flange and tab:., 5 configurations, th~ crimping of the flan~e around the header
plate prevents the filler material or allo~rom~fl-owing well
enough to provide as uniform or consistent a brazed joint or
~` fillet as is ideally desired for high pressure applications.
`l It is the solution of the above and other problems to which
the present invention is directed.
SUMN~RY OF ~E INVENTION
.? Therefore, it is a primary objec~ of this invention to
provid~ a manifold assembly for heat exchangers which can
withstancl high internal operating pressures.
It is another object of this invention to provide a
, manifol~. assembly for heat exchangers which employs an'~ exceptiollally strong and un.iform metallurgical bond between
:, the tank and header plate.
.. It i6 another object of the invention to proYide a~ 2~ manifold assembly for heat exchangers which is easier and less
:~ costly to assemble.
~` These and other objects of the invention are achieved by
I the provision of a manifold assembly which comprises a unitary
tank having ~ substantially U-shaped cross-seGtion and a
unitary header plate which has a substantially U-shaped or
~emi-circular ~ross-section.
The tank comprises an at least partially curved upper
portion which in cross-sectiDn forms the base of the U, a pair
of opposed sides extendi~g from the e~ds of the upper portisn
i 30 and which in cross-~ection form the arms of the U, a pair of
`~ opposed inner side walls, an inner upper wall intermediate the
~:~ inner side walls, a pair of outer side walls, an outer upper
wall intermediate the outer side walls; a pair of longitudinal
~ bottom edges extending between the inner and outer walls at
.; 35 the fre~ ends of the sides, and a pair of longitudinal
channels formed in the bottom edges of the sides. The
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channels divide the bottom edges into inner and outer
portions.
The header plate comprises an inner wall, an outer wall~
and a pair of upper edges intermediate the inner and outer
wall which are matingly received in the channels formed in the
bottom edges of the tank. A plurality ~l~transverse tube
holeci are formed through the header plate along its center
line for receiving the tubes of the condenser or evaporator.
Preferably, a flange or lip is formed around the tube holes to
provide both a tube lead-in and a joint filleting pocket. The
inne~ portions of the bottom edges of the tank form stops
', against which the tubes abut. The tank and header plate are
brazed together along substantially the entire lenyths of
their mating surfaces in order to provide an exceptionally
`.~ 15 uniform and consistent brazed joint or fillet which provides
1 the strength to withstand high internal pressures.
~I The tank and header plate are formed of aluminum and
aluminum alloy materials suitable for furnace brazing, at
least one of the mating surfaces being fabricated with a lower
temperature clad brazing mat:erial, so that when the tank,
- he~der plate, and tubes are assembled, fixtured, and ~razed in
a high temperature brazing furnace, the clad material provides
.,
the brazed material to braze ~he tubes to the header plate and
~, the header plat~ to the tank.
In one aspect of ~he invention; the tank is formed by
. ~ .
- extrusion and the header plate is formed by stamping.
In another aspect of the invention, the tank is extruded
~'j from an a~uminum alloy such as AA3003 or the like, and the
header plate is fabricated from sheet aluminum of a desired
3n ~ased aluminum alloy such a~ AA3003 or the like, clad on both
surfaces with aluminum alloy such as 4004 or any other
~, ~uita~le brazing alloy.
~` In still another aspect of the invention, a plurality of
oppQsed transverse slots can be formed through the tank and
`~ 35 header plate along their center lines to receive baffles
therein, in order to adjust the flow pattern. The baffles are
configured to engage the inner walls and sides of the slots,
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and are also formed of aluminum and aluminum alloy materials
suitable ~or furnace brazing~ so that when the manifold
~. assembly is brazed in a high temperature brazing furnace, the
.~ baffles are brazed to the tank and the header plate.
, 5 In yet another aspect of the invention, a bracket can be
formed unitarily with one of the outer side~lls~of-the tank~
.~' A better understanding of the disclosed embodiments of
: the invention will ~e achieved when the accompanying detailed
d~scription is considered in conjunction with the appended
~ 10 drawings, in which like reference numerals are used for the
,~ same parts as illustrated in the different figures.
BRIEF DESCRIPTION OF T~E DRAWINGS
~ Figure 1 is a perspective view, partially cut away, of a
:~ manifold and heat exchanger assembly in accordance with ~the
~;`, 1~ present invention.
Figure 2 is an end view of the manifold and heat
exchanger assembly of Figure 1.
Figure 3 is a cross-sectional view of the manifold and
~ heat exchanger assembly of Eigure 1, taken along line 3-3 of
-~ 20 Figure 1~
:~ Figure 4 is a cross-sectional view of the maniold and
heat exchanger assembly in accordance with the present
invention, with the tank, header plate, and baffles
~, unassembled.
~5 DE~ D DE~RIPTION OF ~E PREF~RR~D _MBODIMENT8
.
'!" ` In describing the preferred embodiments of the subject
~.~ invention illustrated in the drawings, specific terminology
.~ will be resorted to for the sake of clarity. However, the
invention i5 not intended to be limited to khe specific terms
~o ~elected, and it is to be understood that. each specific
term includes all technicaI equivalence which operate in a
~'. similar manner to accomplish a similar purpose.
Referring now to Figs. 1-4, there is 5hown a manifold and
- heat exchanger assembly 100 in accordance with the present
~, 35 invention. Manifold and heat exchanger assembly 100 comprises
.`~ a manifold assembly 110 into which are inserted a plurality of
.,
~ parallel condenser or evaporator tubes 112.
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Manifold assembly llo comprises a unitary tank 120 having
a substantially U-shaped cross-section and a unitary header
plate 150 having a substantially semi-circular cross-section.
Thus, manifold assembly llo has a substantially circular
. S cross-section. The use of a curved crosssection for both
;'l tank 120 and header plate lSO ena~les manifo ~ assèmbly 110 to
j withstand higher internal pressures than D-shaped manifold
.¦ assemblies.
.' Tank 120 comprises an at least partially curved upper
~l 10 portion 122 which in cross-section forms the base of the U, a
pair of opposed sides 124 extending from the ends of upper
portion 122 and which in cross-section form the arms of the U,
a pair of opposed inner side walls 130, an inner upper wall
132 intermPdiate inner side walls 130, a pair of outer side
walls 140, an outer upper wall 142 intermediate outer sidP
walls 140, and a pair of longitudinal bottom edges 144
:l extending between inner and outer side walls 130 and 140 at
the ~ree ends of sides 124.
: As shown in Figures 1, 2, and 4, inner side walls 130 are
sub~tantially planar and parallel to each other, while one of
- outer side walls 140 is curved and the other is unitarily
provided with a mounting bracket 140a. Inner upper wall 132
is also curved. Outer upper wall 142 is formed with a
substantially planar, central longitudinal rib 142a. A pair
of longitudinal channels 146 are formed in bottom edges 144.
~ Channels 146 divide bottom edges 144 into inner and outer
`~ ~ portions 144a and 144b.
:~ Header plate 150 has a length substantially equaI to the
``l, length of tank 120 and co~prises an inner wall 152, an outer
wall 154 substantially parallel to inner wall 152, and a pair
of longi~udinal upper edges 160 extending between inner and
outer walls 152 and 154~ Inner wall 152 includes a pair o~
:~ opposed inner side walls 162 and an inner lower wall 164
~ intermediate inner side walls 162. A plurality of transverse
`~ 35 tube holes 170 are formed through header plate 150 along its
longitudinal center line for receiving tubes 112 of manifold
`-l and heat exchanger assembly 100. Flanges or lips 172 are
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:. formed around tube holes 170. Flanges 172 are very uniform
formed sections which follow the internal contour of header
plate lS0, i.e. the contour in inner wall 152, thereby
: providing both a tube lead-in and a joint filleting pocket.
`~ 5 Tank 120 preferably is formed ~y extrusion. Header plate
150 preferably is formed by stamping. ~.~nk ~120 can be
extruded from an aluminum alloy such as AA3003 or the like,
. while header plate 150 is fabricated from sheet aluminum of a
desired base aluminum alloy such as AA3003 or the like, clad
~0 on both surfaces with aluminum alloy such as 4004, or other
. suitable brazing alloysO
A plural~ty of opposed transverse slots 180 can be formed
through tank 120 and header plate 150 along their longitudinal
` center lines to receive baffles 190 therein, in order to
:` 15 adjust the flow pattern. Baffles 190 are configured to form
:l a tight fit with inner side walls 130 of tank 120 and inner
';~ side walls 162 of header plate 150, and to extend outwardly of
.l outer upper wall ~42 of tank l20 and outer wall 154 of header
plate 150. Inner portions 144a of bottom edges 144 of tank
120 extend inwardly a suffic:ient amount to act as stops for
~ tubes 112. Inner side and upper walls 130 and 132 of tank 120
! can be coated with clad alloy in order to braze baffles 190 to
`~ inner wall 130.
Tank 120 ls assembled to header plate 150 by inserting
upper edges 160 of header plate 150 into channels 146. This
form of assembly permits a close fit between th abutting
~s ~urfaces of tank 120 and header plate 150~ resulting in
'~ effective brazing. Further, it allows the Piller material or.
~-~ alloy to flow freely to~ provide a uniform and consistent
~razed joint or fillet. Tubes 112 are assembled to header
`~ plate 150 through header flanges 172 with their ends abutting
-, inner portions 144a of bottom edges 144 of tank 120.
Assembly of tank 120 with baffles 190 and header plate
150 can also be accomplished as a unit prior to assembly of
manifold assembly 110 to tubes 112. Where, in certain brazing
`~ operations it is desired to use flux, the flux can be applied
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to the mating surfaces of the parts before their assembly.
The prior art makes this operation very difficult~
j Only a single manifold assembly is shown assembled to the
tubes 112 in Figure 1. However, it should be understood that
in practice, a manifold assembly is assembled to tubes 112 at
either end. ~ ~
In manifolds formed from unitary circular or semi-
I circular tubes as shown in the prior art, internal baffles
:1~ must be installed from either end or through an external sl~t
as shown in the Hoshino et al. patent. The use of the two-
piece construction in accordanr.e with the present invention
allows installation of baffles 190 either before assembly of
tank 120 and header plate 150 or through slots 180 after
assembly of tank 120 and header plate 150.
~;~ 15 In general, tank 120, header plate 150, and baffles 1~4
are formed of aluminum and aluminum alloy materials suitable
! for brazing, at least one of the mating surfaces being
fabricated with a lower temperature clad brazing material.
For example, a lower cost extruded alloy can be used for tank
120, while a clad brazing sheet can be used for header plate
150. Thus, when tank 120, header plate 1~0, baffles 190, and
tubes 112 are assembled, fixtured in place, and brazed in a
~, high temperature brazing furnace, the clad material on header
plate 150 provides the brazed material to braze tubes 112 to
2S header plate 150, header plate 150 to tank 120, and baffles
190 to tank 120 and header plate 150. The pocket provided by
he~der ~langes 172 allows the braze to ~orm a uniform fillet
on flanges 172, which in turn allows a uniform tube to-header
: fillet during braze. ~ ~
I From the above, it is apparent that many modifications
and variations of the present invention are possible in light
of the above teachings. It is therefore to be understood
that, within the scope of the appended claims, the invention
may be practiced otherwise than as specifically described.
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