Heat exchange – Three non-communicating fluids
Patent
1990-12-10
1992-06-16
Rivell, John
Heat exchange
Three non-communicating fluids
165153, 165167, 165916, F28D 710, F28F 308
Patent
active
051217902
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a heat exchanger for insertion in a tank which forms part of a vehicle cooler, said heat exchanger having a plurality of stacked, flat tubes which consist of a first and a second tube half provided each with one circumferential edge flange, said flanges sealingly engaging with one another and forming a lap joint, and which have at each end a hole to establish communication between the tubes and to form an inlet chamber and an outlet chamber for the fluid to be cooled.
Such a heat exchanger may constitute for example a vehicle oil cooler for the cooling of e.g. gear oil and motor oil or hydraulic oil used for driving hydraulically operated devices on the vehicle. As mentioned above, the oil cooler is placed in a tank associated with the normal cooling system of the vehicle, and a mixture of water and glycol flows through as well as around the heat exchanger.
Because of the compactness of presentday vehicles, the available space in the engine compartment tends to diminish. This means that the size of the cooler must be smaller, which in turn means that there is less space available for the oil cooler. As the capacity has to be maintained, new constructions of heat exchangers of this type have become necessary. One such construction is shown in FR 2,428,809 where the heat exchanger consists of a number of flat tubes which are stacked on one another and communicate at their respective ends. At the ends of the tube stack, oil inlets and outlets are provided. Each tube consists of two halves that are joined at the tube periphery by seaming. Another similar construction is shown in DE-OS 3,215,961.
These constructions suffer from the disadvantage that the width of the seam detracts from the inner volume of the tube. As the outer dimensions of the tube are determined by the cooler tank wherein the cooler is to be placed, the space available in the cooler tank will not be optimally utilized, because the seam results in a gap being formed between the wall of the tube and the wall of the cooler tank.
EP-A1 0,106,479 describes a construction wherein each tube in the stack is formed by a strip-shaped tube blank which is bent along its longitudinal central axis and the longitudinal side edges of which are joined after bending in order to form the flat tube. While this construction has enabled an increase of the inner volume of the tube as compared to the above-mentioned constructions, the construction according to EP-A1 0,106,479 requires two end walls to make the construction complete. This increases the cost and also enhances the risk of an untight construction.
The object of the present invention is to eliminate the problems discussed above and to provide a heat exchanger which, with predetermined outer dimensions, yields an increased inner volume and thus a smaller pressure drop across the oil cooler compared to prior art constructions, whereby a higher capacity of heat transmission is obtained, and which is reliable in operation and can be manufactured at low cost.
This object is achieved by means of a heat exchanger of the above-mentioned type, the characteristics of which are defined by the characterizing clause of the appended claim.
A comparison between a heat exchanger according to the invention and a heat exchanger constructed according to the principle of DE-OS 3,215,961 gave the following result:
In the construction according to DE-OS 3,215,961 the manner in which the tube halves are joined to form a flat tube reduces the effective width of the tube by 20%. This in turn deteriorates the cooling performance of the oil cooler by 20% and increases the pressure drop by 40%.
It will thus be evident that the heat exchanger according to the invention is much more efficient than the prior art constructions.
The invention will now be described in more detail, reference being had to the accompanying drawings and the embodiments described below.
FIG. 1 is a side view of a heat exchanger according to the present invention;
FIG. 2 is a view from below of the heat exchanger in FIG. 1;
FIG
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Blackstone Sweden AB
Leo L. R.
Rivell John
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