Heat exchange – Radiator core type – With edge cover or frame means
Reexamination Certificate
1999-09-29
2001-01-30
Lazarus, Ira S. (Department: 3743)
Heat exchange
Radiator core type
With edge cover or frame means
Reexamination Certificate
active
06179050
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a sideplate for a heat exchanger and a heat exchanger.
BACKGROUND OF THE INVENTION
Heat exchangers for vehicles are known to have a header and a tank connected by tubes interspaced by fins, with sideplates providing rigidity. In this type of heat exchanger the fins provide a large surface area for heat transfer and support for the tubes.
Such heat exchangers may be used as radiators or condensers. They may also be used in a number of other applications including charged air coolers.
The sideplates are of particular importance during construction and handling of a heat exchanger. The sideplates may be used to gather the fins and tubes to form a heat exchanger core before securing the core to a header manifold and a tank manifold. Since it is preferable to provide the outermost tubes with fins on their outer edges to ensure good heat transfer, the sideplates may be attached to each of the outer fins.
After assembling the core assembly with the header manifold and the tank manifold, the resultant assembly is brazed in an oven. In the oven, braze cladding coated onto the components melts so that upon cooling, the components are secured together. Sideplates, as is known in the art, can be in a variety of shapes. For example, a sideplate may be a flat elongate plate or a plate curved at either side of an attachment surface. Sideplates may also have strengthening ribs. Suitable materials for sideplates include aluminum or aluminum alloys.
For production reasons, the assemblies are often put in the oven with the tubes positioned in the horizontal. A first problem which may arise with such positioning is “fin drop” which occurs between the fins and the sideplate during the oven melt period. In this condition, the fin begins to move from a symmetrically centered position relative to the sideplate center to an offset position. As a result, the core face edge of the fin is lower than the normal core face on one side and above the normal core face on the opposite side. Fin drop occurs when the force of gravity is greater than the residual friction force at the fin tip area that contacts the tubes and sideplate.
Radiator fins have been made which curl over the end radius of the tube. However, these fins do not always effectively prevent fin drop. Other fins use a bake framing member running close to the fin surface to prevent fin drop, but this can cause discoloration on the core surface or cratering if a clad build up is present.
A second problem is that of “fin dissolution”. The brazing process has to be carried out in a reducing atmosphere to avoid production of metal oxides that would weaken the brazed joints. Unfortunately, during an effective reducing-atmosphere brazing process, the nature of the cladding is such that it causes diffusion of the adjacent material (i.e., the outer fins), which weakens the fin material and therefore the structural stability of the heat exchanger.
A third problem is that the materials of a bake frame, often comprising straps or wires, cause discoloration when in close proximity to cladded surfaces. Furthermore, if the frame material is in contact with the sideplates, the clad material tends to gather near the point of contact. This condition is known as “cratering” and results in marks on the surface of the sideplates. These phenomena reduce the aesthetic qualities of the heat exchanger.
It is accordingly an object of the present invention to at least partially mitigate the problems of the prior art.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a sideplate for a heat exchanger comprising an elongate generally planar web portion, two inner side wall portions and two outer side wall portions. The web portion extends into said inner side wall portions, each said inner side wall portion extending at a respective extremity thereof into a respective outer side wall portion. The inner and outer side wall portions extend out of the plane of the web portion, and at least one of said outer side wall portions extends beyond the web portion.
Preferably each said inner side wall portion extends substantially perpendicular to the planar web portion and has an outer face, and each said outer wall portion lies along the outer face of a respective inner side wall portion.
Advantageously the outer face of said inner side wall portion is contiguous with an outer face of the web portion, and the side plate further has a braze clad material disposed on the outer face of the web portion.
Preferably the braze clad material is disposed only on the outer face of the web portion.
According to a second aspect of the invention there is provided a heat exchanger comprising a header, a tank, a plurality of tubes arranged to connect the header and the tank, a plurality of fins for interspacing the tubes. The fins extend along the length of the tubes, and have at least one outermost tube, which has an outer edge with a first fin. The heat exchanger further comprises a sideplate extending between said header and said tank and having a web portion engaging said first fin, the sideplate having braze cladding on one face of said web portion. The web portion has a thickness, and the sideplate has a flange of double said thickness that extends beyond said web portion to form a fin support portion.
According to a third aspect of the invention there is provided heat exchanger comprising a first manifold having a length and transverse width, a second manifold, a heat exchanger core having a thickness less than said transverse width, and a sideplate disposed between said manifold. The core comprises a plurality of tubes and a plurality of fins, wherein said tubes comprise at least one outermost tube having an outer edge, said outermost tube having a first fin on its outer edge. The sideplate is disposed between the manifolds and has a web portion having one face engaging said first fin, braze cladding being disposed on said one face. The sideplate also has a first portion with a first width substantially equal to said core thickness, and a second portion with a second width greater than said first width. The web portion has a first thickness and the second portion of the sideplate has a flange of double said first thickness, the flange extending beyond the web portion to form a fin support portion.
REFERENCES:
patent: 1743785 (1930-01-01), Leszczyk
patent: 4433227 (1984-02-01), Brittin
patent: 4738308 (1988-04-01), Moranne
patent: 4745966 (1988-05-01), Avery
patent: 5791402 (1998-08-01), Dumetz
patent: 2418132 (1981-06-01), None
patent: 2064751 (1981-06-01), None
patent: 2098313 (1982-11-01), None
Dey LaVoyce
Koo James
Duong Tho
Lazarus Ira S.
Morgan & Finnegan , LLP
Valeo Thermique Moteur
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