EP1515109A2

EP1515109A2 - A heat exchanger and method of manufacturing of a heat exchanger header tank

Info

Publication number: EP1515109A2
Application number: EP04460018A
Authority: EP
Inventors: Marek Filipiak; Robert Racz
Original assignee: Delphi Technologies Inc
Current assignee: Delphi Technologies Inc
Priority date: 2003-09-10
Filing date: 2004-05-31
Publication date: 2005-03-16
Also published as: EP1515109A3

Abstract

The invention relates to a heat exchanger comprising a cooling core consisting of plurality of parallel tubes (3) and cooling fins (4), and two header tanks (5) fluidly connected with the reciprocal ends of each tube. More particularly the invention relates to an improved header tank (5) of such a heat exchanger having a flat face (6) and two flat walls (8) extending perpendicularly from side ends of the flat face. Flat face (6) comprises a plurality of stamped slots (7), wherein each slot (7) has a width corresponding to that of the cooling core tube (2) and comprises grooves (10) going through the thickness of flat walls (8) of the header tank (5) and ending with edges (9) substantially perpendicular to the flat walls (8) of a header tank. The invention relates also to a method of manufacturing such a header tank.

Description

The invention relates to a heat exchanger comprising a cooling core consisting of plurality of parallel tubes and cooling fins, and two header tanks fluidly connected with the reciprocal ends of each tube. More particularly the invention relates to an improved header tank of such a heat exchanger and a method of manufacturing thereof.
Typical heat exchangers comprise oval or circular header tanks having apertures in which cooling core tubes are inserted. Since tubes remain in contact only with one wall of the tank, the surface of joint is small, which decreases the rigidity of construction of the heat exchanger. Additionally oval or circular header tanks are inefficient in outside packaging, as the heat exchanger having oval header tanks requires more storage space, comparing to heat exchanger having the rectangular header tanks and the same performance.
An example of a solution developed to overcome this difficulty is presented in U.S. Pat. No. 5,842,515, which discloses a heat exchanger comprising header tanks having a flat bottom portion formed with a plurality of apertures for receiving the plurality of tubes, a pair of vertical walls extending from both side ends of the flat bottom portion and having a plurality of grooves corresponding to the apertures for guiding the tubes, and a pair of connecting portions extending transversely or bulging outward from the vertical walls, that are joined together to form a hollow inner space and to define the outer surface of the header tank. However such a header tank is relatively complicated due to a number of manufacturing steps.
It is thus an object of the present invention to provide a heat exchanger of the type mentioned above, having an improved rigidity of construction, which ensures an uncomplicated and robust preliminary assembling and which allows an optimal outside packaging. In particular, the aim of the present invention is to provide an improved and simple to manufacture header tank for such a heat exchanger.
According to the present invention there is provided a heat exchanger, in which the flat face of a header tank comprises a plurality of slots made by stamping method, wherein each slot has a width corresponding to that of a cooling core tube and comprises grooves having a width going through the thickness of flat walls of the header tank and ending with edges substantially perpendicular to the flat walls of the header tank.
By stamping slots in the header tank, the cooling core tubes are fitted stronger and the construction of joint between water tubes and radiator tank is more rigid. The depth of the slot secures also the water tube from displacing inside the radiator tank. This solution is also favourable from brazing process point of view, since it provides the increased surface of contact between the tubes and the radiator tank.
Preferably the slots are made by lanceting method and comprise overhangs, which additionally increase the surface of contact between the header tank and cooling core tubes.
Due to the flow of material the length of overhangs may be even greater than the width of the slot.
Preferably the slots have oval shape corresponding to the profile of the cooling core tubes.
Preferably the header tank has a substantially rectangular cross-section.
In another aspect of the present invention, there is provided a method of manufacturing a header tank of a heat exchanger comprising the steps of:
(i) preparing a flat sheet coated with a cladding layer, from which a header tank shall be formed, said sheet having a width corresponding substantially to the perimeter and length corresponding substantially to the length of the formed header tank;
(ii) folding said sheet so as to create a header tank profile, comprising a flat face and two flat walls extending perpendicularly from the side ends of the flat face;
(iii) stamping a plurality of slots for the heat exchanging tubes in said flat face of a header tank, wherein each slot has a width corresponding to that of a cooling core tube and comprises grooves having a width going through the thickness of flat walls of the header tank and ending with the edges substantially perpendicular to the flat walls of the header tank.
The heat exchanger, according to the present invention, is presented below by way of example embodiments in connection with the drawings on which:
Fig. 1 is an axonometric view of a heat exchanger according to the present invention;
Fig. 2 is an axonometric view of a header tank of a heat exchanger according to the present invention, showing slots and grooves prior to fitting the heat exchanging tubes;
Fig. 3 is an axonometric view of a header tank of a heat exchanger according to the present invention after preliminary assembling the tubes;
Fig. 4 is a longitudinal cross-section along the line A-A of Fig. 2, showing the header tank portion, having slots made by a stamping method;
Fig. 5 is a similar longitudinal cross-section showing another embodiment of the header tank portion, having slots made by a lanceting method.
As shown in Fig. 1 the assembled heat exchanger 1 comprises a cooling core 2 consisting of a plurality of parallel water tubes 3 and cooling fins 4, and two header tanks 5 fluidly connected with the reciprocal ends of each tube 3. After preliminary assembling of the heat exchanger 1, it is placed inside an oven where it undergoes a one shot brazing operation.
Fig.2 shows an axonometric, cross-sectional view of one of the two header tanks 5. The header tank 5 was formed from one sheet of aluminium alloy sheet claded with a brazing agent, in process of successive folding. As the result, the header tank 5 has a rectangular cross-section profile and comprises a flat face 6 and two flat walls 8 extending perpendicularly from the side ends of the flat face 6. The longitudinal edges of the profile are inclined and after folding form a closing seam 11.
The flat face 6 comprises a plurality of equidistantly spaced oval shaped slots 7 for the water tubes 3. Slots 7 were made by a stamping method, as an oval shape with a width "d" going through the thickness "D" of the header tank 5 flat walls 8. The width of each slot corresponds to the widths of the cooling core 2 water tubes 3 and is adjusted so as to receive its ends. The drawing shows the header tank 5 sliced along the longitudinal axis of one of the slots 7, and perpendicularly to the header tank 5 longitudinal axis.
Each slot 7 ends with edges 9 that are substantially perpendicular to the flat walls 8 of the header tank 5. That is each slot contains grooves 10 formed in the flat walls 8 of the header tank. The grooves 10 extend vertically from the slots 7 to the some predefined distance and are used to guide the tubes inside the tank. The flanks of the grooves 10 are well-fitted to the oval water tubes 3 shape.
Fig. 3 shows the header tank 5, where the water tubes 3 has been already inserted into slots 7 and grooves 10. Owing to the grooves 10 there is the increased surface of junction between the tube 3 and the header tank 5 and thus the joint between the water tube 3 and the header tank 5 is more rigid and the whole construction of the heat exchanger is stronger. Furthermore the edges 9 block the ends of water tubes during preliminary assembling of the heat exchanger. It is therefore assured that each tube 3 shall be inserted into the slot 7 of the header tank flat face on the same distance until it abuts on the corresponding edge 9 of the slot 7.
Fig 4 the water tubes shows the header tank 5 with the preliminary assembled water tubes 3 in longitudinal cross-section. The slots were made by a stamping method, thus there are substantially no deformations of the flat wall 6 around the slots 7.
Fig 5 shows another embodiment of a header tank, in which the lanceting method was used for creating the slots. This method mixes notching with bulge forming. As a result, a slot rounded with overhangs 12 on the inner side of the tank is formed. Due to the plastic deformation of material, the length of overhangs is approximately equal to the width "D" of the slots 7.
The above embodiments of the heat exchanger according to the present invention are merely exemplary. The figures are not necessarily to scale, and some features may be exaggerated or minimized. It will be also understood to a person skilled in the art that the header tank does not need to have a rectangular cross-section, the heat exchanger can be a radiator or condenser of a motor vehicle air conditioning system.
The method according to the invention is particularly preferred for manufacturing rectangular header tanks, which are of better characteristics than the oval ones. As the appropriate pressing, folding and brazing equipment is in common use in radiator plants; the method can easily be implemented and automated.

Claims

A heat exchanger comprising a cooling core consisting of a plurality of parallel tubes and cooling fins and two header tanks fluidly connected with opposite ends of each tube and having a flat face and two flat walls extending perpendicularly from side ends of the flat face, characterised in that said flat face (6) of the header tank (5) comprises a plurality of stamped slots (7, 7'), wherein each slot (7, 7') has a width corresponding to that of a cooling core tube (3) and comprises grooves (10) going through the thickness of flat walls (8) of the header tank (5) and ending with edges (9) substantially perpendicular to the flat walls (8) of the header tank.
A heat exchanger as claimed in claim 1, characterised in that the slots (7, 7') have oval shape corresponding to the profile of the cooling core tubes (3).
A heat exchanger as claimed in claim 1 or 2, characterised in that the slots (7') comprise overhangs (12).
A heat exchanger as claimed in claim 1 or 2 or 3, characterised in that the header tank (5) has a substantially rectangular cross-section.
A method of manufacturing a header tank of a heat exchanger comprising a cooling core consisting of a plurality of parallel heat exchanging tubes and cooling fins and two header tanks fluidly connected with opposite ends of each tube, characterised in that it said method comprises the steps of:

(i) preparing a flat sheet coated with a cladding layer, from which a header tank shall be formed, said sheet having a width corresponding substantially to the perimeter and length corresponding substantially to the length of the formed header tank;

(ii) folding said sheet so as to create a header tank profile comprising a flat face and two flat walls extending perpendicularly from side ends of the flat face;

(iii) stamping a plurality of slots for the heat exchanging tubes in said flat face of a header tank, wherein each slot has a width corresponding to that of a cooling core tube and comprises, grooves having a width going through the thickness of flat walls of the header tank and ending with edges substantially perpendicular to the flat walls of the header tank.
A method as claimed in claim 5, characterised in that the slots are formed by lanceting method and comprise overhangs.