Method of making a heat exchanger having a tubular manifold with transverse baffles

In a heat exchanger of the kind suitable for use as a condenser in a motor vehicle air conditioning installation, a manifold has a cylindrical tubular wall and is divided into compartments by means of baffles, which are introduced through an open end of the tubular wall. Heat exchange tubes extend into the compartments of the manifold through apertures formed in the tubular wall. After the baffles have been slid into place within the tubular wall, deformations are formed in the tubular wall so as to retain the baffles in place, prior to insertion of the heat exchange tubes and brazing to secure the components of the assembly sealingly together.

FIELD OF THE INVENTION 
This invention relates to heat exchangers of the kind comprising at least 
one manifold having a tubular wall and divided into compartments by at 
least one transverse baffle, together with a plurality of parallel heat 
exchanger tubes, each of which communicates into a said compartment of the 
manifold through an aperture formed in the tubular wall of the latter. 
BACKGROUND OF THE INVENTION 
Such a heat exchanger is useful in particular as a condenser in an air 
conditioning installation for a motor vehicle. A heat exchanger of this 
kind is described in the specification of published European patent 
application No. EP 0 377 936A, in which the tubular wall of the manifold 
is formed with diametral slots, with each baffle being introduced 
laterally through one of these slots and having an appropriate contour 
such as to enable it to come into abutment against the ends of the slot. 
The baffle, thus located in position, is subsequently brazed to the 
tubular wall. A disadvantage of this arrangement is that the manufacture 
of the tubular wall is complicated by the need to machine the slots, while 
the shape of each baffle has to be irregular. In addition, the slots form 
sites for possible leakage. 
DISCUSSION OF THE INVENTION 
An object of the present invention is to overcome the above mentioned 
drawbacks. To this end, according to the invention in a first aspect, a 
method of making a heat exchanger comprising at least one manifold having 
a tubular wall and divided into compartments by at least one transverse 
baffle, together with a multiplicity of parallel heat exchange tubes, each 
of which communicates with a compartment of the manifold into which it 
extends through an aperture formed in the said tubular wall of the latter, 
is characterised in that each baffle is introduced into the tubular wall 
through an open end of the latter so as to locate it in its correct 
position, the tubular wall being subsequently deformed on either side of 
the said baffle whereby to secure the latter in place. 
The ends of the tubular wall may in particular be closed by means of 
supplementary transverse baffles, which are secured in position in the 
same way as the baffles dividing the manifold into compartments. 
Preferably, during deformation of the tubular wall the latter is deformed 
inwardly into the interior of the manifold. 
According to a preferred feature of the invention, the tubular wall is 
brazed to each baffle and/or to the heat exchange tubes whereby to seal 
the joint thereby created against ingress of fluid, and the brazing 
operation is preferably then carried out by melting a fusible metallic 
coating which is provided on at least one of the components to be brazed. 
Where, before being deformed, the said tubular wall has an irregular 
internal profile surrounding each baffle and spaced from the latter 
radially over a significant proportion of its perimeter, according to a 
preferred feature of the invention the said deformation brings it 
substantially into contact with the respective baffle over its whole 
perimeter. This is applicable especially where the tubular wall comprises 
a rolled metallic strip having two opposed edges which are joined together 
along a generatrix of the wall, defining an inwardly directed bead. 
According to the invention in a second aspect, a heat exchanger is made by 
a method according to the invention, and comprises at least one manifold 
divided into compartments by at least one transverse baffle, together with 
a multiplicity of parallel heat exchange tubes, each of which communicates 
with a compartment of the manifold into which it extends through an 
aperture formed in the latter, the manifold comprising a tubular wall 
which is pierced by the said apertures and which surrounds the edge of the 
or each baffle, the tubular wall being deformed on either side of the or 
each baffle whereby to retain the latter in position. 
Further features and advantages of the invention will appear more clearly 
from the detailed description of a preferred embodiment of the invention 
which follows, being given by way of example only and with reference to 
the accompanying drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
The heat exchanger shown in the drawings is intended in particular to act 
as a condenser in an air conditioning installation for the cabin of a 
motor vehicle. It includes a manifold 1 having a tubular wall 2 which is 
formed with a multiplicity of apertures 3. A respective one of a 
multiplicity of heat exchange tubes 4 is fitted in each of the apertures 
3. The transverse cross section of each heat exchange tube 4 is elongated 
in the transverse direction of the manifold, the tubes 4 being parallel to 
each other and disposed at right angles to the longitudinal direction 
defined by the manifold. One end 5 of each of the heat exchange tubes 4 
lies within the manifold 1, with its opposite end being arranged to lie 
similarly within a further manifold not shown. This further manifold is 
typically similar to the manifold 1 and is arranged parallel to it. 
Inserts 6, made from strips of thin metal sheet curved into the form of a 
sine wave, are located in the gaps between the heat exchange tubes 4 so as 
to make thermal contact with the latter. 
In the drawings, the tubular wall 2 is shown as being deformed into the 
interior of the manifold around the apertures 3, so as to define outwardly 
extending hollow elements 7. The space between two adjacent apertures 7 
may, alternatively, be undeformed in known manner, so that it then has a 
profile corresponding to that of the tubular wall 2. 
A number of baffles extend transversely within the manifold. These consist 
in the present example of two endmost or supplementary baffles 8a and 8b 
(referred to herein for convenience collectively by the reference numeral 
8), and intermediate or dividing baffles 9a and 9b which are similarly 
referred to herein collectively by the reference numeral 9. The baffles 8 
cooperate with the tubular wall 2 so as to define the interior space of 
the manifold between them. This internal space is divided into a number of 
compartments 10a, 10b, 10c and 10d by the intermediate baffles 9. It 
should be noted that the reference numerals 10b and 10c correspond to two 
different compartments or alternatively to the same compartment, according 
to whether or not there is a further baffle (not shown) between the 
baffles 9a and 9b. 
Each of the baffles 8 and 9 is retained in place by means of deformations 
11 formed in the tubular wall 2. In this particular example, each of these 
deformations is integrally moulded so that it projects into the interior 
of the manifold, extending as a continuous bead circumferentially around 
the tubular wall 2 as can be seen in FIG. 3. Two of these beads 11 are 
provided for each baffle, arranged on either side of the latter 
(considered in the longitudinal direction of the manifold). The beads 11 
may be replaced by deformations of any other suitable type, which may in 
particular be discontinuous in the circumferential direction. 
The peripheral edge of each of the baffles 8 and 9 is sealingly brazed to 
the inner surface of the tubular wall 2, while the outer surface of the 
heat exchange tubes 4 is similarly brazed sealingly to the edges of the 
apertures 3. 
In the manufacture of the heat exchanger, the tubular wall 2 is provided in 
a generally cylindrical shape, with its internal transverse cross section 
being uniform, substantially circular, and large enough to enable the 
baffles 8 and 9, which also have a circular profile, to slide 
longitudinally within the tubular wall. Each of these baffles is 
introduced through one of the open ends of the tubular wall and is slid 
longitudinally into place within it. The beads 11 (or other suitable 
deformations as mentioned above) are then formed, as are the hollow 
elements 7 which retain the baffles in position. The deformations may be 
formed in any suitable known way (e.g. by pressing or rolling) 
The tubular wall 2 typically consists of a rolled metal strip which is 
joined, for example by welding, edge to edge so as to define an inwardly 
projecting flange. The baffles are thus unable to penetrate into the 
tubular wall unless the internal diameter of the latter is at least equal 
to that of the baffle plus the thickness of the flange, so that an 
appreciable gap exists between the outer edge of the baffles and the inner 
surface of the tubular wall over the major part of the perimeter. It is 
thus beneficial that the deformation of the latter shall be sufficiently 
great to eliminate this gap, so enabling the tubular wall to be brazed 
sealingly to the edges of the baffles. 
After the tubular wall has been suitably reformed to define the various 
deformations 11 and 7, the apertures 3 can be formed and the ends 5 of the 
heat exchange tubes 4 can then be introduced into the interior of the 
manifold 1 through the apertures 3. The ends 5 of the tubes 4 are brought 
into abutment against the inner surface of the tubular wall 2 as can be 
seen in FIG. 2. 
Sealing between the outer surface of the heat exchange tubes 4 and the 
apertures 3, and sealing between the edges of the baffles 8 and 9 and the 
inner surface of the tubular wall 2, is obtained by brazing using a 
fusible metallic coating which may be melted by heating the assembled heat 
exchanger. This coating is preferably provided on the outer surface of the 
tubular wall 2 so that this latter can be brazed to the heat exchange 
tubes, and also on the baffles themselves so that they can be brazed to 
the wall 2. It should however be noted that such a coating is omitted from 
the inner surface of the tubular wall, thus avoiding any danger of the 
braze metal partly obstructing the open ends of the heat exchange tubes.