Multi-Circuit Heat Exchanger
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.
The present invention relates to a multicircuit exchanger.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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:
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- 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.
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.
The abovementioned mechanical stresses arise from the differential expansions of the heat-exchange tubes generated by the differences in temperature between the two circuits.
“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.
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:
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- the mechanical connection element consists in a brace.
- the brace, or mechanical means, is immediately next to a fluid circulation tube that is closest to the separation.
- the mechanical connection element mechanically connecting the two collector rings is placed between two adjacent tubes of the two circuits.
- 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.
- 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.
- the mechanical connection element or brace consists in an extension of the partitions separating said chambers.
- the mechanical connection element or brace consists of a tube identical to the other heat-exchange tubes but in which no fluid circulates.
- 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.
- 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.
- 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.
- the exchanger is completely mechanically assembled by crimping with no braising.
- the separation partition separating the two circuits comprises a small orifice allowing the fluid to travel from one circuit to the other.
- the multicircuit exchanger consists mainly of an aluminum alloy and is assembled by braising.
- the multicircuit exchanger may comprise boxes produced by injection of plastics, these boxes being assembled to the collector rings by crimping.
Embodiments of the invention will be described below as nonlimiting examples, making reference to the appended drawings in which:
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.
In the nonlimiting exemplary embodiments illustrated in
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- two independent circuits A and B, a collector ring C1 which is separated into two independent portions by a wall P1,
- a second collector ring C2 which is also separated into two independent portions by a wall P2,
- 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,
- 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,
- 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,
- a mechanical connection S which mechanically connects the two collector rings.
In a third exemplary embodiment according to the invention illustrated in
In a fourth exemplary embodiment according to the invention illustrated in
In a fifth exemplary embodiment according to the invention illustrated in
In a sixth exemplary embodiment according to the invention illustrated in
In a seventh exemplary embodiment according to the invention illustrated in
In a sixth exemplary embodiment according to the invention illustrated in
In a ninth exemplary embodiment according to the invention illustrated in
In an eighth exemplary embodiment according to the invention illustrated in
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.
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.
Type: Application
Filed: Dec 11, 2007
Publication Date: Feb 10, 2011
Inventors: Christian Riondet (Bourgogne), Jean-Michel Haincourt (Authon Du Perche), Jean-Marc Lesueur (Reims)
Application Number: 12/525,934
International Classification: F28F 9/02 (20060101);