EP2317271A1

EP2317271A1 - U-flow radiator having an end tank with a Z-shape separator

Info

Publication number: EP2317271A1
Application number: EP09174690A
Authority: EP
Inventors: Tomasz Dariusz Frankiewicz; Krzysztof Obsadny; Grzegorz Marcin Jarosik
Original assignee: Delphi Technologies Inc
Current assignee: Delphi Technologies Inc
Priority date: 2009-10-30
Filing date: 2009-10-30
Publication date: 2011-05-04

Abstract

A U-flow heat exchanger (10) comprising of a heat exchange core (12) having a plurality of tubes (14), an I/O tank (24) connected to a first end of the core through a header plate (32), and a return tank (26) connected to a second end of the core, said I/O tank being divided into a first chamber (50) and a second chamber (52) by a separating member (54), a first group (G1) of tubes being in communication with the first chamber through the header plate, a second group (G2) of tubes being in communication with the second chamber through the header plate, characterized in that the separating member is configured such that a third group (G3) of tubes, arranged between the first and the second groups, is in communication with the first chamber on one side of the separating member and with the second chamber on the other side of the separating member.

Description

TECHNICAL FIELD

The invention relates to a U-flow heat exchanger for a motor vehicle.

BACKGROUND OF THE INVENTION

Heat exchangers such as radiators are commonly used in automobiles having an internal combustion engine to convey heat away from hot engine components to the cooler ambient air. A radiator is part of a closed loop system wherein the radiator is hydraulically connected to passageways within an engine through which a heat transfer fluid, such as a mixture of water and ethylene glycol, is circulated.
A typical U-flow radiator is formed of a central core having a multitude of parallel tubes with fins therebetween to increase the surface area for optimal heat dissipation. Hydraulically attached to either end of the core that corresponds with the tube openings is an end tank. After absorbing heat from a heat source, the heat transfer fluid enters a first chamber of a first end tank, called I/O tank (In & Out tank), where the fluid flow is uniformly distributed through a first group of parallel tubes. The fluid flows through the first group of parallel tubes to a second end tank, called return tank, where the fluid flow is redirected towards the I/O tank through a second group of parallel tubes. Then the fluid enters a second chamber of the I/O tank before exiting the radiator returning to the heat source to repeat the heat transfer process. As the fluid flows through the parallel tubes between the two end tanks, heat is radiated to the ambient air. To assist in the heat transfer, a stream of ambient air is blown perpendicularly relative to the radiator core through the fins.
To separate the two chambers, the I/O tank is provided with a separating wall located in the middle of the tank, across the tank and between two tubes.
In cars where U-flow radiators are used with brazed aluminum core and one raw of parallel tubes, we can observe cracking of tubes located in the middle of the core. This failure is located near the header plate of the I/O tank, on both sides of the separating wall but also at the opposite side where the return tank is located. Cracking of tubes is caused by thermal stress in the tubes associated with thermal tube expansion.

SUMMARY OF THE INVENTION

In order to solve the above mentioned problems, the present invention provides a U-flow heat exchanger comprising of a heat exchange core having a plurality of tubes, an I/O tank connected to a first end of the core through a header plate, and a return tank connected to a second end of the core, said I/O tank being divided into a first chamber and a second chamber by a separating member, a first group of tubes being in communication with the first chamber through the header plate, a second group of tubes being in communication with the second chamber through the header plate, characterized in that the separating member is configured such that a third group of tubes, arranged between the first and the second groups, is in communication with the first chamber on one side of the separating member and with the second chamber on the other side of the separating member.
According to other features of the present invention:

the third group comprises flat tubes with at least two parallel ports, the two ports being arranged on each side of the separating member;
the third group comprises single tubes which are arranged on each side of the separating member;
the separating member comprises a main longitudinal wall and two opposite transversal end walls;
the edge of the separating member adjacent to the tube openings comprises a tightening member;
the tightening member comprises cut-outs complementary to the header plate and to the tube ends;
the arrangement tightness of the separating member in the I/O tank is adjusted in order to obtain an adjusted fluid leakage between the two chambers.

The objects, features and advantages of the present invention will become apparent to those skilled in the art from analysis of the following written description, the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

figure 1 is a an exploded perspective view showing a radiator having a Z-shape separator according to a first embodiment of the present invention;
figure 2 is a perspective view showing the I/O end tank equipped with the Z-shape separator of figure 1;
figure 3 is a partial perspective view showing the arrangement of the Z-shape separator of figure 1 with regards to the tubes and header plate, the separator being partially cut;
figure 4 is a perspective view showing the Z-shape separator of figure 1;
figure 5 is a view similar to the view of figure 3 showing the Z-shape separator entirely;
figure 6 is a cross-sectional view showing the arrangement of single tubes on each side of the separator according to a second embodiment of the present invention;
figure 7 is a perspective view similar to the view of figure 5 showing a separator with an additional gasket according to a third embodiment of the present invention;
figure 8 is a partial perspective view showing the arrangement of the additional gasket of figure 7 between the Z-shape separator and the header plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 is an exploded perspective view of a first embodiment of the heat exchanger 10 according to the present invention. The heat exchanger 10 includes a core 12 having a bundle of flat B-tubes 14 that are substantially parallel. The tubes 14 are jointed longitudinally by conventional means such as welding, brazing or soldering to a supporting structure such as fins 16 between the tubes 14. The core 12 has two core ends 18, 20 corresponding with tube openings 22.
Each core end 18, 20 is attached to an end tank assembly 24, 26 that comprises of an end tank 28, a gasket 30, and a header plate 32. As shown on figures 3 and 6, the tube openings 22 are affixed to elongated perforations 34 located on the header plate 32 by conventional means such as welding, brazing or soldering. The header plate 32 is mechanically attached to the end tank 28 with the gasket 30 between the contact surfaces of the header plate 32 and of the end tank 28.
In reference more particularly to Fig. 2, the end tank 28 has two longitudinal side walls 36, 38 that are integral with a bottom wall 40 along a longitudinal axis A1 and two end walls 42, 44 along a latitudinal axis A2 defining an elongated cavity 46. The tank opening is defined by a perimeter tank foot 48 that protrudes laterally outward from the exterior edges of the two side walls 36, 38 and exterior edges of the two end walls 42, 44.
The end tank 28 is shown substantially rectangular in appearance. The present invention does not intend the substantially rectangular shape to be limiting, but can also encompass other elongated shapes with an open face along the longitudinal axis.
The heat exchanger 10 shown on the figures is a U-flow radiator. It comprises a first end tank assembly 24 called I/O tank to which the coolant circuit is connected upwardly and downwardly, and a second end tank assembly 26 called return tank, which redirects the fluid flow from the I/O tank 24 to the I/O tank 26.
After absorbing heat from a heat source, the heat transfer fluid or coolant enters a first chamber 50 of the I/O tank, where the fluid flow is uniformly distributed through a first group G1 of parallel tubes 14. The fluid flows through the first group G1 of parallel tubes 14 to the return tank 26, where the fluid flow is redirected towards the I/O tank 24 through a second group G2 of parallel tubes 14. Then the fluid enters a second chamber 52 of the I/O tank 24 before exiting the radiator 10 returning to the heat source to repeat the heat transfer process.
Generally, the incoming coolant flow is hot and the coolant flow exiting the radiator 10 is relatively cold, with regards to the incoming coolant flow.
To separate the two chambers 50, 52, the elongated cavity 46 of the I/O tank 24 is provided with a separating member 54 located substantially in the middle of the tank 24.
According to the present invention, the separating member 54 is a Z-shape separator which is configured such that there is a U-flow of coolant not only between the two groups G1, G2 of tubes 14 but also between two portions of each single tube of a third group G3. So there is a "double U-flow" in the radiator 10.
According to the first embodiment of the invention, shown on figures 1 to 5, the Z-shape separator 54 is constituted of a main longitudinal wall 56 substantially orthogonal to the header plate 32, said main longitudinal wall 56 being provided at each extremity with respectively a first transversal end wall 58 and a second transversal end wall 60, each transversal wall 58, 60 extending towards opposite side walls 36, 38 of the end tank 28. The transversal walls 58, 60 are orthogonal to the longitudinal wall 56 and their edge comes into tightening contact with the corresponding inner surface of the end tank 28 in order to form a seal between the two chambers 50, 52, as shown on figures 2 and 3.
As shown more particularly on figure 3, each transversal wall 58, 60 extends transversally between two adjacent flat tubes 14 and the main longitudinal wall 56 extends above the flat tube openings 22 of the third group G3 of tubes 14. As the tubes 14 in the first embodiment are all flat B-tubes having two parallel ports 62, 64, the main longitudinal wall 56 bears on the middle portion of the tubes 14, such that a first port 62 of the tube 14 is opened into the first chamber 50 whereas a second port 64 of the same tube 14 is opened into the second chamber 52.
According to alternative embodiments (not shown), the tubes 14 could be multiport tubes having more that two parallel ports.
Advantageously, the separator 54 has special cut-outs forming teeth 66 along the lower edge 68 to be in direct contact with the tubes 14 in order to ensure good tightness between the two chambers 50, 52 and in order to avoid tubes deformation during clinching operation of the different parts forming the I/O tank assembly 24.
According to the first embodiment, the upper edge 70 of the separator 54 (orientated downwardly on figures 2 and 4) is provided with a complementary profile to match with the corresponding profile of the end tank 28 bottom wall 40, in order to ensure tightening contact and good separation between the two chambers 50, 52. For example, the upper edge 70 comprise a bumped portion 72 corresponding to a recess 74 formed in the bottom wall 40 for arranging a connection port 76.
As can be seen on figure 3, the coolant flow enters the first chamber 50 of the I/O tank 24 where it is uniformly distributed through the first group G1 of tubes 14 and through the first port 62 of the third group G3 of tubes 14. The fluid flows through the core 12 and through the return tank 26 where it is redirected towards the I/O tank 24. The fluid flows into the second chamber 52 through the second group G2 of tubes 14 and through the second port 64 of the third group G3 of tubes 14. It is represented schematically on figure 3 by arrow F1 which shows the fluid transfer from the first group G1 to the second group G2 and by arrow F2 which shows the fluid transfer from the first ports 62 of the third group G3 to the second ports 64 of the third group G3.
Thanks to the separator 54 according to the invention, it has been created two U-flows F1, F2 substantially perpendicular to each other which allows a better distribution of temperature longitudinally along the I/O tank 24 and along the radiator 10 in general.
Previously, the thermal stress between the cold side and the hot side of the radiator 10 was located exclusively along two adjacent tubes in the middle of the radiator 10. Thanks to the separator 54 according to the present invention, the thermal stress is spread on several tubes 14.
One could note that the size of the transitional zone between the cold side and the hot side of the radiator 10 can be adjusted easily by selecting the appropriate length for the main longitudinal wall 56 of the separator 54.
The separator 54 can be orientated in such a way that the hot side of the third group G3 of tubes 14 is located either on the front side of the radiator 10 or on the rear side of the radiator 10, depending for example on the particular arrangement of the radiator 10 in the vehicle.
Advantageously, the arrangement tightness of the separator 54 in the I/O tank 24 is configured such that an adjusted fluid leakage is created between the two chambers 50, 52. For example, there is an adjusted space between the edges of the separator 54 and the corresponding inner walls of the end tank 28 such as to create a fluid leakage of 250 1/min. The leakage can be up to 800 1/min. The leakage can also be created and adjusted thanks to the arrangement of through holes in the separator 54.
This adjusted leakage can help to avoid thermal stresses in the tubes as the coolant leaking through the separator can flow quicker than by the tubes which can decrease the temperature more quickly on the second side of the separator 54 corresponding to the second chamber 52. This leakage constitutes a third U-flow. Of course, it is necessary to adjust the leakage in order to not lose too much cooling performance in the radiator.
According to a second embodiment of the present invention, shown on figure 6, the third group G3 of tubes 14 is constituted of single tubes 78 arranged separately on each side of the separator 54. This embodiment allows simplifying the design of the separator 54 lower edge 68. Each single tube 78 could have one or several ports.
According to a third embodiment of the present invention, represented on figures 7 and 8, the tightening on separator 54 can be achieved by adding an additional gasket 80 on the separator lower edge 68. The additional gasket 80 can exist as a separate part or can be made of one pied with the gasket 30 used to tighten the end tank 28 to the header plate 32.
According to the various embodiments described above, the separator 54 is made of a separate part assembled to the I/O tank 24. Alternatively, the separator 54 could be made of one piece with the end tank 28.

Claims

A U-flow heat exchanger (10) comprising of a heat exchange core (12) having a plurality of tubes (14), an I/O tank (24) connected to a first end of the core (12) through a header plate (32), and a return tank (26) connected to a second end of the core (12), said I/O tank (24) being divided into a first chamber (50) and a second chamber (52) by a separating member (54), a first group (G1) of tubes (14) being in communication with the first chamber (50) through the header plate (32), a second group (G2) of tubes (14) being in communication with the second chamber (52) through the header plate (32),
characterized in that the separating member (54) is configured such that a third group (G3) of tubes (14), arranged between the first and the second groups (G1, G2), is in communication with the first chamber (50) on one side of the separating member (54) and with the second chamber (52) on the other side of the separating member (54).
Heat exchanger (10) according to claim 1, characterized in that the third group (G3) comprises flat tubes (14) with at least two parallel ports (62, 64), the two ports (62, 64) being arranged on each side of the separating member (54).
Heat exchanger (10) according to claim 1, characterized in that the third group (G3) comprises single tubes (78) which are arranged on each side of the separating member (54).
Heat exchanger (10) according to anyone of the preceding claims, characterized in that the separating member (54) comprises a main longitudinal wall (56) and two opposite transversal end walls (58, 60).
Heat exchanger (10) according to claim 4, characterized in that the edge (68) of the separating member (54) adjacent to the tube openings (22) comprises a tightening member (66, 80).
Heat exchanger (10) according to the preceding claim, characterized in that the tightening member (66, 80) comprises cut-outs complementary to the header plate (32) and to the tube ends.
Heat exchanger (10) according to anyone of the preceding claims, characterized in that the arrangement tightness of the separating member (54) in the I/O tank (24) is adjusted in order to obtain an adjusted fluid leakage between the two chambers (50, 52).