U.S. patent application number 12/525934 was filed with the patent office on 2011-02-10 for multi-circuit heat exchanger.
Invention is credited to Jean-Michel Haincourt, Jean-Marc Lesueur, Christian Riondet.
Application Number | 20110030935 12/525934 |
Document ID | / |
Family ID | 38520613 |
Filed Date | 2011-02-10 |
United States Patent
Application |
20110030935 |
Kind Code |
A1 |
Riondet; Christian ; et
al. |
February 10, 2011 |
Multi-Circuit Heat Exchanger
Abstract
The present invention relates to an exchanger comprising at
least two circuits, this exchanger comprising: a series of tubes
for the circulation of fluid of one or other of the two circuits,
at least two collector rings, each connected to the opposite ends
of the tubes, said tubes opening respectively into said collector
rings, a partition provided in each of said collector rings
defining at least one separation in order to isolate the first
circuit from the second circuit of fluid, a mechanical connection
means connecting the structure of the inlet chamber to the
collection chamber is designed to reduce significantly the
structural mechanical stresses existing in the separation between
the two circuits, characterized in that the mechanical means
consists in a total or partial closing off of at least one tube
situated next to the partitions.
Inventors: |
Riondet; Christian;
(Bourgogne, FR) ; Haincourt; Jean-Michel; (Authon
Du Perche, FR) ; Lesueur; Jean-Marc; (Reims,
FR) |
Correspondence
Address: |
HOWARD & HOWARD ATTORNEYS PLLC
450 West Fourth Street
Royal Oak
MI
48067
US
|
Family ID: |
38520613 |
Appl. No.: |
12/525934 |
Filed: |
December 11, 2007 |
PCT Filed: |
December 11, 2007 |
PCT NO: |
PCT/EP2007/063740 |
371 Date: |
October 25, 2010 |
Current U.S.
Class: |
165/173 |
Current CPC
Class: |
F28F 9/0209 20130101;
F28F 2270/02 20130101; F28F 2225/08 20130101; F28F 2009/0287
20130101; F28D 1/0443 20130101 |
Class at
Publication: |
165/173 |
International
Class: |
F28F 9/02 20060101
F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 6, 2007 |
FR |
FR 0700815 |
Claims
1. An exchanger (1) comprising at least two circuits (A) and (B),
said exchanger (1) comprising: a series of tubes for the
circulation of fluid of one or other of the two circuits (A) or
(B), at least two collector rings, each connected to the opposite
ends of said tubes, said tubes opening respectively into said
collector rings, a partition (P1 and P2) provided in each of said
collector rings defining at least one separation in order to
isolate the first circuit (A) from the second circuit (B) of fluid,
a mechanical connection means (S) connecting the structure of an
inlet chamber to a collection chamber which reduces the structural
mechanical stresses existing in the separation between the two
circuits (A and B), characterized in that said mechanical
connection means (S) totally or partially closes off of at least
one tube situated next to said partitions (P1) and (P2).
2. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) comprises a brace.
3. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) is immediately next to a tube
that is closest to the separation.
4. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) mechanically connecting said
two collector rings is placed between two adjacent tubes of the two
circuits (A and B).
5. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) mechanically connecting said
two collector rings is placed in a region of said exchanger (1) in
which the temperature and therefore expansion is at an intermediate
level between those of the two circuits (A and B).
6. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) mechanically connecting said
two collector rings comprises at least two solid or hollow bars or
braces placed on each side of said partition existing between said
chambers.
7. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) comprises an extension of said
partitions separating said chambers.
8. An exchanger (1) according to claims claim 1, characterized in
that said mechanical connection means (S) comprises a tube
identical to said other tubes but in which no fluid circulates.
9. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) comprises at least one tube
identical to said other tubes but having a fluid inlet and/or
outlet orifice that is restricted in order to limit the flow rate
of fluid.
10. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) comprises at least one tube
identical to said other tubes but having a wall thickness that is
greater at least in one zone situated close to a fluid inlet and/or
outlet orifice in order to limit the flow rate of fluid and to
mechanically reinforce at least locally said mechanical connection
means (S).
11. An exchanger (1) according to claim 1, characterized in that
said mechanical connection means (S) comprises several tubes
identical to said other tubes but in which no fluid circulates,
said several tubes being placed on either side of said partition
separating the two circuits (A and B).
12. An exchanger (1) according to claim 1, characterized in that
said exchanger (1) is completely mechanically assembled by crimping
with no braising.
13. An exchanger (1) according to claim 1, characterized in that
said partition separating the two circuits (A and B) comprises an
orifice allowing the fluid to travel from one circuit to the
other.
14. An exchanger (1) according to claim 2, characterized in that
said brace is immediately next to a tube that is closest to the
separation.
Description
[0001] The present invention relates to a multicircuit
exchanger.
[0002] More particularly, but not exclusively, its subject is an
exchanger comprising at least two independent or partially
independent circuits inside which at least two fluids which may or
not be different circulate before being cooled by a circulation of
external air.
[0003] It applies in particular to the multicircuit exchangers used
in the automobile industry in order to cool two elements which have
different cooling needs such as the heat engine and the gearbox for
example.
[0004] It is particularly well suited to multicircuit exchangers
used in the case of a hybrid engine in order to cool the electric
motor on the one hand and the heat engine on the other hand.
[0005] For reasons of manufacturing cost and to make integration
into the vehicle easier, it is preferable to perform the cooling
functions of the two fluids in a multicircuit exchanger rather than
in two separate exchangers. Conversely, it is imperative to
thermally isolate the two circuits as much as possible by removing
as much as possible the thermal stresses due to the differences in
temperature between the two circuits. Specifically, the fluids
circulating in the two separate circuits do not necessarily have
the same cooling energy needs nor necessarily the same inlet and
outlet temperatures. In order to optimize the operation and
longevity of the exchanger, it is therefore important to minimize
the thermal stresses.
[0006] Conventionally, exchangers comprises a series of thin light
alloy cylindrical tubes, often of flattened shape leading into two
collector rings. The seal between these tubes and the collector
ring is provided by the interposition of elastic seals or by
braising. Very thin light alloy interlocked strips folded in an
accordion shape are inserted between the tubes in order to increase
the contact area between the exchanger and the ambient air
travelling between the tubes; these interlocked strips
conventionally being called inserts.
[0007] Conventionally, multicircuit exchangers comprise a
separating partition in the two collector rings in order to
separate the two circuits. Unfortunately the structural elements
close to this partition (mainly the thin tubes) do not withstand
the mechanical stresses (particularly fatigue) due to the
difference in temperature (particularly because of the temperature
difference cycles) existing between the two circuits. The thinnest
structures such as the tubes are the most susceptible to breakage
and to generating leaks.
[0008] This situation is accentuated in the case of braised light
alloy tubes to the extent that the heat treatments necessary for
braising make the light alloy less rigid and more vulnerable to the
creation of cracks originating from the thermal stresses
particularly with respect to the bending or stretching
stresses.
[0009] In order to attempt to remove these disadvantages, it has
been proposed to increase the cross section of the partition or
even to double it but the problem remains because the differential
expansions between the hot tubes and the relatively cooler tubes
still exist and create internal fatigue stresses that are too
great.
[0010] Furthermore, it should be noted that the thermal stresses at
the border between the two circuits are considerable when the
thermal gradient existing at this location between the two circuits
is great.
[0011] In order to remedy these major disadvantages, the invention
departs from the architectures mentioned above and proposes an
exchanger comprising at least two circuits, this exchanger
comprising: [0012] a series of tubes for the circulation of fluid
of one or other of the two circuits, [0013] at least two collector
rings, each connected to the opposite ends of the tubes, said tubes
opening respectively into said collector rings, [0014] a partition
provided in each of said collector rings defining at least one
separation in order to isolate the first circuit from the second
circuit of fluid, [0015] a mechanical connection means connecting
the structure of the inlet chamber to the collection chamber is
designed to reduce significantly the structural mechanical stresses
existing in the separation between the two circuits.
[0016] According to the invention, this exchanger is characterized
in that the mechanical means consists in a total or partial closing
off of at least one tube situated next to the partitions.
[0017] The abovementioned mechanical stresses arise from the
differential expansions of the heat-exchange tubes generated by the
differences in temperature between the two circuits.
[0018] "Separation" means an imaginary line connecting the two
partitions that are present respectively in each of the collector
rings and that mark the boundary or limit between each of the two
circuits. In a conventional manner, this separation consists in a
straight line or a plane extending in the plane of extension or in
the axis of the tubes and/or of the partitions.
[0019] In nonlimiting embodiments, the multicircuit exchanger
according to the invention can have additional elements and/or
features described below taken in isolation or in combination:
[0020] the mechanical connection element consists in a brace.
[0021] the brace, or mechanical means, is immediately next to a
fluid circulation tube that is closest to the separation. [0022]
the mechanical connection element mechanically connecting the two
collector rings is placed between two adjacent tubes of the two
circuits. [0023] the mechanical connection element or brace
mechanically connecting the two collector rings is placed in a
region of the exchanger in which the temperature and therefore
expansion is at an intermediate level between those of the two
circuits. [0024] the mechanical connection element mechanically
connecting the two collector rings consists of at least two solid
or hollow bars or braces placed on each side of the separation
partition existing between the distribution chambers. [0025] the
mechanical connection element or brace consists in an extension of
the partitions separating said chambers. [0026] the mechanical
connection element or brace consists of a tube identical to the
other heat-exchange tubes but in which no fluid circulates. [0027]
the mechanical connection element or brace consists of at least one
heat-exchange tube identical to the other heat-exchange tubes but
having a fluid inlet and/or outlet orifice that is restricted in
order to limit the flow rate of fluid. [0028] the mechanical
connection element or brace consists of at least one heat-exchange
tube identical to the other heat-exchange tubes but having a wall
thickness that is greater at least in one zone situated close to
the fluid inlet and/or outlet orifice in order to limit the flow
rate of fluid and to mechanically reinforce at least locally the
connection element. [0029] the mechanical connection element or
brace consists of several tubes identical to the other
heat-exchange tubes but in which no fluid circulates, these tubes
being placed on either side of the wall separating the two
circuits. [0030] the exchanger is completely mechanically assembled
by crimping with no braising. [0031] the separation partition
separating the two circuits comprises a small orifice allowing the
fluid to travel from one circuit to the other. [0032] the
multicircuit exchanger consists mainly of an aluminum alloy and is
assembled by braising. [0033] the multicircuit exchanger may
comprise boxes produced by injection of plastics, these boxes being
assembled to the collector rings by crimping.
[0034] Embodiments of the invention will be described below as
nonlimiting examples, making reference to the appended drawings in
which:
[0035] FIG. 1 is a schematic cross section of a multicircuit
exchanger with two independent circuits according to the prior
art.
[0036] FIG. 2 shows schematically an exemplary embodiment of an
exchanger with two independent circuits according to the
invention.
[0037] FIGS. 3 to 8 are variant embodiments of an exchanger with
two independent circuits according to the invention also in
schematic cross section.
[0038] In the rest of the description, the expression "mechanical
means" will be used to define in a general manner the subject of
the invention. Nevertheless, it is clear that this expression can
also be reflected in the term "brace", in particular in order to
mark the fact that this mechanical means connects the two collector
boxes.
[0039] FIG. 1 shows an exchanger 1 with two independent circuits as
is conventionally produced according to the prior art. It comprises
a first circuit A inside which a first fluid circulates and a
circuit B inside which a second fluid circulates. This exchanger
comprises two collector rings C1 and C2 responsible for collecting
the fluid. These collector rings are each separated in two portions
by a wall P1 and P2. A set of tubes (in this instance numbering 7)
t1 to t7 connect the two collector rings. Thin interlocked strips
made of aluminum alloy folded in the shape of an accordion are
inserted between the tubes to increase the area of contact between
the tubes and the surrounding air. Each circuit comprise an inlet
and an outlet. The fluid of the circuit A enters the circuit via
the inlet Ea and leaves via the outlet Sa after having circulated
in the tubes t1, t2, t3, t4. The fluid of the circuit B enters the
circuit via the inlet Eb and leaves via the outlet Sb after having
circulated in the tubes t5, t6, and t7. If the average temperature
of the first fluid in the circuit A is higher than the average
temperature of the second fluid of the circuit B, then the tubes t1
to t4 are hotter than the tubes t5 to t7. In this case, the tubes
t1 to t5 tend to expand more than the tubes t5 to t7. The result of
this is compression and bending stresses in the tubes t1 to t4 and
stretching and bending stresses in the tubes t5 to t7. Because of
the extremely hyperstatic aspect of the tube/collector rings
mechanical attachment, it is the tube t5 and the structure close to
the end of this tube t5 which is most subjected to the risk of
developing a crack by the fatigue effect of alternating
stretching/bending stress.
[0040] In the nonlimiting exemplary embodiments illustrated in
FIGS. 2 to 8, the exchanger mainly comprises [0041] two independent
circuits A and B, a collector ring C1 which is separated into two
independent portions by a wall P1, [0042] a second collector ring
C2 which is also separated into two independent portions by a wall
P2, [0043] three tubes t1, t2, and t3 which connect in a sealed
manner the collector ring C1 to the collector ring C2 and which
allow the first fluid of the circuit A to circulate from an inlet
Ea to an outlet Sa, [0044] three tubes t5, t6, and t7 which connect
in a sealed manner the collector ring C1 to the collector ring C2,
and which allow the second fluid of the circuit B to circulate from
an inlet Eb to an outlet Sb, [0045] thin strips of light alloy
folded in the shape of an accordion which are inserted between the
tubes to increase the area of contact between the tubes and the
surrounding air, [0046] a mechanical connection S which
mechanically connects the two collector rings.
[0047] In a third exemplary embodiment according to the invention
illustrated in FIG. 2, the mechanical connection S consists of a
tube t4 made of light alloy. For the purpose of uniformity, and to
reduce the manufacturing cost, this type of tube is similar to the
tubes used for the circulation of fluid. However, in the tube t4
used as an additional structure, no fluid circulates. To prevent
any circulation of fluid in this tube, one or two stopper(s) 3
close(s) off one or both end(s) of the tube t4. Here again, since
the tube t4 is not supplied with a fluid, it is at an intermediate
temperature which somewhat reduces the stresses due to the
temperature differences that exist between the two circuits.
[0048] In a fourth exemplary embodiment according to the invention
illustrated in FIG. 3, the mechanical connection S, or brace,
consists of two tubes t3 and t4 made of light alloy. These two
tubes are closed off at one or both of their ends and therefore, as
in the preceding example, are not traversed by the fluids. Here
again, since the tubes t3 and t4 are not supplied with a fluid,
they are at an intermediate temperature which somewhat reduces the
stresses due to the temperature differences that exist between the
two circuits.
[0049] In a fifth exemplary embodiment according to the invention
illustrated in FIG. 4, the mechanical connection S consists of two
tubes t4 and t5 made of light alloy. These two tubes are closed off
at one or both of their ends and therefore, as in the preceding
example, are not traversed by the fluids. Here again, since the
tubes t4 and t5 are not supplied with a fluid, they are at an
intermediate temperature which somewhat reduces the stresses due to
the temperature differences that exist between the two
circuits.
[0050] In a sixth exemplary embodiment according to the invention
illustrated in FIG. 5, the mechanical connection S consists of four
tubes t3, t4, t5 and t6 made of light alloy. These four tubes are
closed off at one or both of their ends and therefore, as in the
preceding example, are not traversed by the fluids. Here again,
since the tubes t4, t5, t6, and t7 are not supplied with a fluid,
they are at an intermediate temperature which somewhat reduces the
stresses due to the temperature differences that exist between the
two circuits.
[0051] In a seventh exemplary embodiment according to the invention
illustrated in FIG. 6, the mechanical connection S consists of a
tube t4 made of light alloy. This tube is partially closed off and
is traversed by the fluid but with a weaker flow rate. The
influence of such a tube on the structural stresses is therefore
less than if it was a tube that was completely closed off but all
the same makes it possible to somewhat reduce the stresses due to
the temperature differences that exist between the two
circuits.
[0052] In a sixth exemplary embodiment according to the invention
illustrated in FIG. 6, the mechanical connection S consists of two
tubes t3 and t4 made of light alloy. These tubes are partially
closed off and are traversed by the fluid but with a weaker flow
rate. The influence of such tubes on the structural stresses is
therefore weaker than if they were tubes that were completely
closed off, but all the same makes it possible to somewhat reduce
the stresses due to the temperature differences that exist between
the two circuits.
[0053] In a ninth exemplary embodiment according to the invention
illustrated in FIG. 8, the mechanical connection S consists of
three tubes t3, t4 and t5 made of light alloy. These tubes are
partially closed off and are traversed by the fluid but with a
weaker flow rate. The influence of such tubes on the structural
stresses is therefore weaker than if they were tubes that were
completely closed off but makes it possible all the same to
somewhat reduce the stresses due to the temperature differences
that exist between the two circuits.
[0054] In an eighth exemplary embodiment according to the invention
illustrated in FIG. 9, the mechanical connection S consists of a
metal plate P, in this instance made of light alloy, which passes
completely through the exchanger 1. This plate P is braised to the
periphery of each collector ring in order to ensure the seal
between the two circuits, and therefore forms a rigid link between
the two collector rings. Thus this plate P is at an intermediate
temperature which reduces the stresses due to the temperature
differences that exist between the two circuits. This plate may
advantageously be replaced by a hollow plate (FIG. 10).
[0055] Those skilled in the art will be able to apply this concept
to many other similar systems without departing from the context of
the invention defined in the attached claims.
* * * * *