Heat exchange – Tubular structure
Reexamination Certificate
1999-12-10
2001-06-05
Yeung, James C. (Department: 3743)
Heat exchange
Tubular structure
C165S179000, C165S183000, C165S174000, C029S890049
Reexamination Certificate
active
06241012
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a folded tube and method of making same for a heat exchanger in a motor vehicle.
2. Description of the Related Art
It is known to provide a tube for a heat exchanger such as a condenser in an air conditioning system of a motor vehicle. The tube typically carries a first fluid medium in contact with its interior while a second fluid medium contacts its exterior. Typically, the first fluid medium is a liquid or a two-phase liquid and gas mixture and the second fluid medium is a gas. Where a temperature difference exists between the first and second fluid mediums, heat will be transferred between the two via heat conductive walls of the tube.
It is also known to provide corrugated fins or ribs in the interior of the tube to increase the surface area of conductive material available for heat transfer to cause turbulence of the fluid carried in the interior of the tube and to increase the burst strength of the tube. One known method of making such a tube is to physically insert a corrugated fin into the generally flattened tube after the tube has been manufactured. This is an extremely difficult process since the corrugated fin to be inserted into the tube is extremely thin and subject to deformation during the insertion process.
Another known method of forming a tube for a heat exchanger is to extrude the tube in an extrusion process. In this construction, internal ribs are formed during the extrusion. However, these extruded tubes are relatively expensive to produce.
Yet another known method of forming a tube for a heat exchanger is to provide a flat, elongated sheet with lugs and the ends of the sheet are folded to form the tube. The ends of the tube are then brazed. An example of such a tube is disclosed in U.S. Pat. No. 5,386,629. In this patent, the tube may have flow paths between the lugs. However, the quality of the folded tube to header joints is related to how small the outside web shoulders can be with the smaller the better to prevent leakage.
It is desirable to provide a folded tube with very small outside web shoulder radii. It is also desirable to provide a method to achieve small web shoulder for a folded tube. It is further desirable to provide a folded tube for enhancing heat transfer of the heat exchanger. Therefore, there is a need in the art to provide a folded tube for a heat exchanger of a motor vehicle that achieves these desires.
SUMMARY OF THE INVENTION
Accordingly, the present invention is a folded tube for a heat exchanger. The folded tube includes a base, a top spaced from and opposing the base, a first side interposed between the base and the top along one side thereof, and a second side interposed between the base and the top along another side thereof. The folded tube also includes at least one of the base and the top having at least one internal web having an initial web width and an initial outside shoulder radius and being compressed to compress the at least one internal web to a final web width less than the initial web width and a final outside shoulder radius less than the initial outside shoulder radius and defining a plurality of fluid ports.
Also, the present invention is a method of making a folded tube for a heat exchanger. The method includes the steps of providing a generally planar sheet, folding the sheet, and forming at least one internal web having a first fold portion and a second fold portion. The method also includes the steps of compressing the at least one internal web to compress a width and outside shoulder radius of the at least one internal web. The method further includes the steps of folding the sheet and forming a base and a top opposing the base and a first side interposed between the top and the base and a second side interposed between the top and the base such that the at least one internal web contacts either one of the top or the base to provide a plurality of fluid ports.
One advantage of the present invention is that a folded tube for a heat exchanger such as a condenser is provided for an air conditioning system of a motor vehicle for condensing liquid refrigerant. Another advantage of the present invention is that the folded tube is stamped and folded and is more economical to manufacture than an extruded tube. Yet another advantage of the present invention is that the folded tube has a small web shoulders for better brazing to minimize the number of potential leaks in manufacturing. Still another advantage of the present invention is that a method of making the folded tube is provided by coining metal inside to achieve very small outside web shoulder radii. A further advantage of the present invention is that the folded tube may have the webs enhanced with vertical serrations to achieve fluid mixing and enhance heat transfer of the heat exchanger. Yet a further advantage of the present invention is that a method of making the folded tube is provided by enhancing the webs by vertical serrations introduced by special rolls during web coining to achieve fluid mixing, eliminating the need for secondary turbulators.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.
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Rhodes Eugene E
Whitlow Greg
Yu Wen Fel
McKinnon Terrell
Shelton Larry I.
Visteon Global Technologies Inc.
Yeung James C.
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