Priority is hereby claimed to German Patent Application No. DE 10 2006 054 814.0, filed Nov. 22, 2006, the entire contents of which is incorporated herein by reference.
The present invention relates to a soldered flat tube for condensers and/or evaporators in air-conditioning systems, and more particularly, to tubes for condensers and/or evaporator in motor vehicles. The tubes can be produced by deformation of one or more aluminum-containing sheet-metal strips, having two narrow sides and two wide sides. The tubes can include inner passages with a hydraulic diameter which is greater than or equal to 0.254 mm, and can have a tube wall thickness of less than 0.25 mm.
Soldered flat tubes for condensers are known from EP 273 164 A1. Flat tubes with inner passage hydraulic diameters in the range from 0.381-1.778 mm are nowadays standard equipment for what are known as parallel-flow condensers.
In many other cases, flat tubes for condensers and/or evaporators are produced by extrusion, in which case there are manufacturing engineering limits on the realization of particularly small hydraulic diameters combined with significantly smaller tube wall thicknesses and passage wall thicknesses. From a cost perspective too, the extrusion process does not always stand comparison with other processes. This is true at least if the flat tubes have dimensions (D;d) as required for condensers/evaporators.
Furthermore, in the case of flat tubes for condensers and/or evaporators, it is necessary to take into account the significantly higher internal pressure compared to other heat exchangers in motor vehicles, which has meant that in practice hitherto the tube wall thickness of flat tubes of this type has been at best approximately between 0.25 mm and 0.30 mm. The hydraulic diameters of current commercially available flat tubes for condensers and/or evaporators are in the range from approximately 1.10-1.60 mm or slightly above.
There are also a number of earlier patent applications in the name of the applicant, but these have not at present been published. One of these bears the application number DE 10 2006 006 670.7 and proposes flat tubes with extremely small wall thicknesses for cooling liquid coolers and for charge air coolers.
Another convention heat exchanger is disclosed in EP 1 681 528 A1. This publication specifically claims flat tubes for condensers. It represents an advanced stage of development, since it likewise relates to very thin-walled flat tubes. The sheet-metal strip forming the passages is to have a thickness of less than 0.1 mm. In the Applicant's opinion, the flat tubes disclosed in that document, despite all their advantages, also have a significant drawback, namely that the stability of the flat tubes is insufficient.
One independent object of the invention is to provide lightweight but also high-performance and low-cost condensers and/or evaporators or flat tubes for them which are to have improved stability. Some embodiments of the present invention achieve this and other desirable objects.
According to the invention, both narrow sides of the flat tube are reinforced in that they are to have a thickness which is greater than the tube wall thickness, for example at least double the tube wall thickness. This proposal simplifies production of the heat exchanger network comprising flat tubes of this type and also corrugated fins, since this network becomes easier to assemble. In the case of flat tubes from the prior art, which have only a single reinforced narrow side, it is necessary to ensure that all the flat tubes are positioned with the reinforced narrow side facing in one direction, generally forward toward the cooling-air stream. This consideration is obviated because the present proposal reinforces both narrow sides.
Furthermore, according to an embodiment which is currently preferred, the flat tube comprises three sheet-metal strips, two sheet-metal strips forming the tube wall and the third sheet-metal strip representing an inner insert.
In a refinement of this idea, the two sheet-metal strips which form the tube wall are identical in form, in that one longitudinal edge of the sheet-metal strips has a larger arc and the other longitudinal edge of the sheet-metal strips is configured with a smaller arc, the sides of the sheet-metal strips being disposed oppositely to one another in such a manner that the larger arc of one longitudinal edge of one sheet-metal strip engages around the smaller arc of the longitudinal edge of the other sheet-metal strip, and vice versa.
Further reinforcement of the two narrow sides is achieved by the inner insert having two deformed longitudinal edges which bear against the inside of the narrow sides.
Alternatives provide for it to be possible to produce the flat tube either from one single sheet-metal strip or from two sheet-metal strips.
In the case of flat tubes which can be produced from two sheet-metal strips, one narrow side comprises a bend which lies in a fold of the sheet-metal strip and the other narrow side is formed by one longitudinal edge of the sheet-metal strip being configured with a larger arc, which is placed around a smaller arc at the other longitudinal edge of the sheet-metal strip, the second sheet-metal strip being configured as a corrugated inner insert, the longitudinal edges of which bear or do not bear against the inside of the narrow sides.
The passage wall thickness is approximately between 0.03-0.10 mm or slightly above. In the case of flat tubes made from a single sheet-metal strip, the tube wall thickness and the passage wall thickness have the same dimensions.
The tube wall thickness is in the range from approximately 0.08 mm-0.20 mm, with the passage wall thickness being between 0.03-0.10 mm. This applies to both two-part and three-part flat tubes.
In terms of the flat tube dimensions, the small dimension (d) of the flat tube is approximately 0.8-1.3 mm and the large dimension (D) is approximately between 8 and 20 mm, preferably approximately 12-16 mm.
It has been concluded that a particularly suitable hydraulic diameter of the passages is between 0.30 and 0.70 mm, with a range between 0.40 and 0.60 mm standing out in particular by virtue of performance advantages.
The condenser or evaporator as a component of an air-conditioning system of motor vehicles which condenser or evaporator has a soldered heat exchanger network made up of flat tubes and fins which are disposed between the flat tubes and through which cooling air flows is described in greater detail below.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
The accompanying drawings predominantly show a plurality of enlarged views of various flat tube cross sections, which can advantageously be used for condensers of air-conditioning systems. In the drawings:
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
All the flat tubes have the common features whereby the hydraulic diameter hD of the passages K is greater than 0.254 mm, the tube wall thickness Wd is less than 0.25 mm and both narrow sides 1 are reinforced by having a greater wall thickness Sd than the remaining tube wall thickness Wd. The passage wall thickness Kd may be between 0.03 and 0.15 mm.
The flat tubes illustrated in
The exemplary embodiment shown in
The two flat tubes illustrated in
The four illustrations corresponding to
By contrast,
Finally,
Various features and advantages of the invention are set forth in the following claims.
Number | Date | Country | Kind |
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10 2006 054 814.0 | Nov 2006 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2007/084823 | 11/15/2007 | WO | 00 | 9/28/2010 |