Heat exchanger header tank and heat exchanger comprising same

A heat exchanger comprising a pair of header tanks arranged as spaced apart from each other, and a plurality of heat exchange tubes arranged in parallel between the pair of header tanks and each having opposite ends joined to the respective header tanks,

• each of the heat exchanger header tanks comprising a header forming plate, a tube connecting plate and an intermediate plate interposed between the two plates, the header forming plate, the tube connecting plate and intermediate plate being arranged in superposed layers and brazed to one another, the header forming plate being provided with an outward bulging portion extending longitudinally thereof and having an opening thereof closed with the intermediate plate, the tube connecting plate being provided at a portion thereof corresponding to the outward bulging portion with a plurality of tube insertion holes arranged longitudinally of the tube connecting plate at a spacing and extending through the thickness thereof, the intermediate plate having communication holes extending through the thickness thereof for causing the respective tube insertion holes of the tube connecting plate to communicate with interior of the outward bulging portion of the header forming plate therethrough, the heat exchange tubes having their opposite ends inserted into the respective tube insertion holes of the pair of header tanks and brazed to the respective header tanks.

A process for fabricating a heat exchanger characterized by:

• subjecting a brazing sheet having a brazing material layer over at least one surface thereof to press work to make a header forming plate having an outward bulging portion with an inner surface thereof covered with the brazing material layer,
• making a tube connecting plate having a plurality of tube insertion holes arranged longitudinally thereof at a spacing, a cover plate integral with each of opposite side edges thereof and extending over the entire length thereof and an engaging portion forming lug integral with an outer end of the cover wall, by subjecting a brazing sheet having a brazing material layer over opposite surfaces thereof to press work,
• making an intermediate plate having a plurality of communication holes arranged longitudinally thereof at a spacing by subjecting a bare metal material to press work,
• making two tacked assemblies each by arranging the three plates in superposed layers with the intermediate plate positioned in the middle, inwardly bending the engaging portion forming lug to form an engaging portion and causing the engaging portion to engage with the header forming plate to tack the three plates,
• preparing a plurality of heat exchange tubes and fins,
• arranging the two tacked assemblies as spaced apart with the tube connecting plates opposed to each other,
• alternately arranging the heat exchange tubes and the fins,
• placing opposite ends of the heat exchange tubes into the respective tube insertion holes of the tube connecting plates of the two tacked assemblies, and
• brazing the three plates of each of the tacked assemblies to one another to make header tanks, brazing the cover wall of each tacked assembly to corresponding side faces of the header forming plate and the intermediate plate thereof and the engaging portion thereof to the header forming plate, and brazing the heat exchange tubes to the header tanks and each of the fins to the heat exchange tubes adjacent thereto at the same time.