This application claims priority to DE 101 47 192.0, a German patent application filed Sep. 25, 2001, pursuant to 35 U.S.C. xc2xa7119(a)-(d).
This invention pertains to heat exchangers for vehicles and more particularly to such heat exchangers that include a block of heat exchange elements including flat tubes.
Flat tube block heat exchangers have rows of flat tubes that may be alternated with corrugated fins. The ends of the flat tubes provide flow paths between tanks located at the opposite ends of the flat tubes and the flat tubes extend from one header plate to another header plate at the opposite end of the flat tubes. Typically, the flow paths created by the flat tubes extend generally perpendicular to the header plates at the ends of the tubes. The header plates are manufactured and supplied separately from the flat tubes and are typically made from relatively heavy materials. Further, the header plates occupy space at the collection tanks located at either end of the flat tube block heat exchanger.
Headerless flat tubes have been formed by placing two tube halves adjacent to one another where the ends of the tube halves have been deformed such that the broad sides may be connected. Drawn or welded tubes have been slit in their narrow sides in order to deform the ends and connect the broad sides. In both cases the connected broad sides form a xe2x80x9cpeak-and-valleyxe2x80x9d surface that is not conducive to directing flow from a transverse direction into the flat tubes. Examples of heat exchangers with these types of flat tubes are disclosed in German Patent Application Nos. DE 100 16 113.8 and DE 100 19 268.8, both of which are incorporated herein by reference.
While these constructions can perform satisfactory for their intended purpose, there is always room for improvement. For example, the pressure loss of the medium flowing through the collection tanks and flat tubes of a block heat exchanger could be reduced in order to improve their application opportunities, especially in the vehicle field.
In one form, the invention provides a heat exchanger that includes a pair of collection tanks spaced opposite each other. The tanks are fluidly connected by a plurality of flat tubes that provide flow paths between the tanks. The flat tubes have opposing ends that correspond to one of the tanks and each end has two broad sides and two narrow sides. Each broad side has an inner surface and is deformed to expose the inner surface. The exposed inner surfaces of each flat tube are bonded to the exposed inner surface of any adjacent flat tube to define a fluid barrier with the corresponding tank.
In one form, each of the narrow sides is connected to an edge of the corresponding tank.
According to one form, the deformed broad sides have two bends of about 90xc2x0 with the bonded inner surfaces arranged in parallel orientation to the broad sides of any adjacent flat tube. Alternatively, the flat tubes are arranged in oblique orientation relative to a longitudinal axis of the flat tubes and the broad sides have a first bend of about 90xc2x0 and a second bend that corresponds to the angle of the oblique orientation. In another alternative, the deformed broad sides are curved to expose the inner surface with a cross-section that is semicircular or semielliptical.
According to one form, the bonded broad sides define a plurality of fluid inflow funnels to the flat tubes.
According to one form, the flat tubes are formed from two half-shells.
In one form, each of the narrow sides includes a cut extending parallel to a longitudinal axis of the flat tubes, the cut separates the broad sides at the tube end.
In one form, each of the narrow sides includes two cuts that separate the broad sides at the tube ends and define a tab in each narrow side. In one form, the tab is bent inward into the flat tube.
In yet another form of the invention, a heat exchanger includes a pair of tanks spaced opposite each other, the tanks are fluidly connected by a plurality of spaced apart flat tubes to provide flow paths between the tanks. Each flat tube has opposing ends corresponding to one of the tanks, each end has a first broad side, a second broad side, and two narrow sides, each broad side has an inner surface and an outer surface. Each first broad side being deformed to expose the inner surface of the first broad side, and each of the exposed inner surfaces of each first broad side is bonded to the outer surface of any adjacent second broad side to define a fluid barrier with corresponding tank.
In another form, the invention provides a method for manufacturing a heat exchanger includes the steps of: cutting a plurality of flat tube ends to separate each tube end into a pair of broad sides; deforming each of the broad sides to expose an inner surface of the broad side; abutting the exposed inner surface of each of the broad sides to an exposed inner surface of an adjacent broad side of another tube; affixing a tank on the flat tube ends; and bonding the adjacent broad sides to each other and the flat tube ends to the tanks.
In one form, each flat tube end includes a pair of narrow sides in the flat tube end, and the bonding step includes bonding the narrow sides of the flat tube ends to the tank.
In yet another form, a method is provided for manufacturing a heat exchanger and includes the steps of: cutting a plurality of flat tube ends to separate each tube end into a pair of broad sides; deforming each of the broad sides to expose an inner surface of the broad side; abutting the exposed inner surface of one of the broad sides to an outer surface of an adjacent broad side; affixing a tank on the flat tube ends; and bonding the adjacent broad sides to each other and the flat tubes with the tanks.
In one form, each flat tube end includes a pair of narrow sides in the flat tube end and the bonding step includes bonding the narrow ends of the flat tube ends to the tank.
Objects and advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein and in the associated figures and appended claims.