Device for fixing a heat exchanger operating at high temperature

A fixing lug provided on a fluid chamber of the heat exchanger has an elongate opening along which there is able to slide a bolt ensuring the clamping of the lug on a receiving lug. This sliding enables the heat exchanger to expand without mechanical stress.

FIELD OF THE INVENTION 
The invention concerns a device for fixing to a support of a heat exchanger 
designed to have fluid pass through it at high temperature, notably for 
fixing, to the chassis and/or bodywork of a vehicle, a radiator for 
cooling the booster air for the thermal engine of this vehicle, the device 
being distributed over at least two fixing zones at a distance from each 
other and having in each of these zones at least one contact surface 
belonging to the support, at least one contact surface belonging to the 
exchanger and a clamping appliance suitable for applying one of the said 
contact surfaces against the other, with the optional interposing of at 
least one intermediate element. 
BACKGROUND OF THE INVENTION 
The known devices of this type have the effect of immobilising the 
respective contact surfaces of the heat exchanger and of the support with 
respect to each other in all the fixing zones. As a result, when there is 
thermal expansion of the heat exchanger during its operation, there are 
mechanical stresses which may result in permanent deformation or rupture 
of components or welds. 
The aim of the invention is to remedy these drawbacks. 
DISCUSSION OF THE INVENTION 
The invention relates notably to a device for fixing to a support of a heat 
exchanger designed to have fluid pass through it at high temperature, 
notably for fixing, to the chassis and/or bodywork of a vehicle, a 
radiator for cooling the booster air for the thermal engine of this 
vehicle, the device being distributed over at least two fixing zones at a 
distance from each other and having in each of these zones at least one 
contact surface belonging to the support, at least one contact surface 
belonging to the exchanger and a clamping appliance suitable for applying 
one of the said contact surfaces against the other, with the optional 
interposing of at least one intermediate element and makes provision for 
it to offer, in at least one of the fixing zones, referred to as the 
sliding zone, a possibility of relative sliding of the contact surfaces of 
the support and exchanger, thus making it possible to absorb the thermal 
expansion of the exchanger without excessive mechanical stress. 
Optional characteristics of the device according to the invention, 
complementary or alternative, are set out below: 
The heat exchanger comprising at least one elongate fluid chamber through 
which the fluid enters the exchanger and/or leaves it, communicating with 
at least one row of fluid circulation tubes aligned in the longitudinal 
direction of the fluid chamber and extending transversely to the latter, 
it has two fixing zones situated in the vicinity of the fluid chamber and 
mutually distant in the longitudinal direction thereof, and offers in one 
of these fixing zones a possibility of relative sliding in the 
longitudinal direction of the fluid chamber. 
The heat exchanger comprising two elongate parallel fluid chambers through 
which the fluid enters the exchanger and leaves it, connected together by 
at least one row of fluid circulation tubes aligned in the longitudinal 
direction of the fluid chambers and extending transversely thereto, it 
includes two fixing zones situated in the vicinity of the two fluid 
chambers respectively and offers, in one of these fixing zones, a 
possibility of relative sliding in the longitudinal direction of the 
tubes. 
The exchanger being designed to cool a fluid entering it at high 
temperature through a first fluid chamber and which leaves it again at a 
substantially lower temperature through the second fluid chamber, it has 
four fixing zones, including three sliding zones, situated in pairs in the 
vicinity of the two fluid chambers respectively and mutually distant in 
the longitudinal direction of the latter, the relative sliding taking 
place in the longitudinal direction of the fluid chambers, for one of the 
sliding zones, adjacent to the first of these, and in the longitudinal 
direction of the tubes for the other two sliding zones, adjacent to the 
second fluid chamber. 
It comprises, in each sliding zone, a lug projecting from the wall of the 
corresponding fluid chamber, one of the faces of which defines a contact 
surface of the exchanger and in which is provided an opening through which 
a clamping appliance such as a bolt passes, fixed with respect to the 
support, the said opening being elongate in the direction of sliding in 
order to enable the clamping appliance to move therein with respect to the 
lug. 
The clamping appliance affords the clamping of a stack comprising, in the 
following order, a fixing lug secured to the support, a first intermediate 
element in the form of a washer, the said lug of the fluid chamber and a 
second intermediate element in the form of a washer. 
Each intermediate washer comprises, juxtaposed in the direction of the 
stack, an outer region of width greater than the width of the elongate 
opening, which bears on the corresponding face of the lug of the fluid 
chamber, and an internal region of width slightly less than the width of 
the opening, which enters the opening and provides guidance of the 
clamping appliance along it. 
It comprises, in at least one fixing zone, a lug projecting from the wall 
of the corresponding fluid chamber, and means for fixing this lug with 
respect to the support without any possibility of sliding. 
The said lugs all extend in the same mid-plane of the heat exchanger, 
parallel to the longitudinal directions of the fluid chambers and of the 
tubes, and substantially orthogonally to the walls of the fluid chambers. 
The intermediate elements are made from a material with a low coefficient 
of friction and good resistance to compression. 
Another object of the invention is a heat exchanger comprising at least two 
contact surfaces distant from each other, suitable for forming part of a 
device as defined above, at least one of the said contact surfaces being 
able to slide with respect to a contact surface belonging to a support 
when it is applied against it with the optional interposing of at least 
one intermediate element. 
The said contact surface is advantageously defined by one of the faces of a 
lug projecting from the wall of a fluid chamber, in which there is formed 
an opening suitable for having a clamping appliance such as a bolt pass 
through it, the said opening being elongate in the direction of sliding in 
order to enable the clamping appliance to move therein with respect to the 
lug.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 depicts a radiator for cooling booster air for the thermal engine of 
a motor vehicle, comprising in a conventional manner an inlet fluid 
chamber 1, an outlet fluid chamber 2 and a bank of tubes 3. The two fluid 
chambers are elongate in the same direction, vertical in the figure, and 
are connected at their top end respectively to an inlet manifold 4 and to 
an outlet manifold 5 for the air to be cooled. The bank 3, of rectangular 
parallelepipedal shape overall, extends from one of the fluid chambers to 
the other and includes a multiplicity of tubes, not shown individually, 
elongate horizontally and mutually aligned from top to bottom in the 
figure, the two ends of each tube opening out respectively into the two 
fluid chambers. Thus the air to be cooled can pass from the fluid chamber 
1 to the fluid chamber 2 by flowing in parallel through the different 
tubes in the bank 3, where it is cooled by an air current passing through 
the latter perpendicularly to the plane of the figure. 
Each of the fluid chambers has two fixing lugs marked 6 and 7 for the fluid 
chamber 1, and 8 and 9 for the fluid chamber 2. These lugs are for example 
cast in a single piece with the aluminium alloy fluid chambers, so as to 
extend along the mid-plane of the heat exchanger, parallel to the plane of 
FIG. 1, whilst projecting orthogonally with respect to the wall 10 (FIG. 
2) of each fluid chamber, the opposite way to the other fluid chamber. The 
lugs 6 and 8 are adjacent to the ends of the fluid chambers opposite to 
the manifolds 4 and 5, and the lugs 7 and 9 are distant from the lugs 6 
and 8 in the direction of these manifolds. 
According to the invention, the lug 6 on the fluid chamber 1 and the lugs 8 
and 9 on the fluid chamber 2 have respective elongate holes 11, 12 and 13 
passing through them. The hole 11 is elongate in the longitudinal 
direction of the fluid chambers, and the holes 12 and 13 in the 
longitudinal direction of the tubes in the bank 3. As for the lug 7, this 
has a circular hole 14 passing through it, which is both substantially in 
line with the hole 11 and in line with the hole 13. 
As FIGS. 2 and 3 show by way of example for the lug 9, each of the lugs 6 
to 9 is designed to be applied against a lug 15 secured to the chassis or 
bodywork of the vehicle for fixing the heat exchanger. This fixing is 
achieved by means of a bolt 16, the shank of which passes through the hole 
13 and which clamps, between its head 17 and its nut 18, a stack composed, 
in this order, of a steel washer 19, a first intermediate washer 20, the 
lug 9, a second intermediate washer 21, the lug 15 and a nut locking 
washer 22. Each of the intermediate washers 20 and 21 is annular in shape 
and has an L-shaped section comprising an outer leg 23 which is clamped 
between the washer 19, or the lug 15, and the opposite face 24, 25 of the 
lug 9, and an inner leg 26 substantially adjacent to the wall of the hole 
13. The intermediate washers 20 and 21 are produced for example from 
sintered alloy soaked in oil, so as to have a low coefficient of friction 
and high resistance to compression. The lug 7 can be fixed in a 
conventional manner by virtue of its circular hole 14. 
When the different parts of the heat exchanger are in thermal equilibrium, 
the bolt 16 ensures the mutual immobilisation of all the components 
through which it passes, and in particular the lugs 9 and 15. The lugs 6 
and 8 are immobilised in the same way, and the lug 7 in a conventional 
manner, with respect to the chassis of the vehicle, which ensures stable 
fixing of the heat exchanger. 
The commencement and stoppage of the operation of the engine, and the 
changes in speed, cause a differential expansion of the different parts of 
the heat exchanger. The fluid chamber 1, by which the air to be cooled 
enters, may for example be raised to 180.degree. C., and the fluid chamber 
2, by which the cooled air leaves, to 75.degree. C. This gives rise to a 
significant variation on the one hand in the length of the fluid chamber 1 
and on the other hand in the distance between the two fluid chambers, 
compared with the idle state at ambient temperature. The lug 6 therefore 
has a tendency to move away from the lug 7, and the lugs 8 and 9 
respectively from the lugs 6 and 7. These movements are permitted by the 
device according to the invention, the lug 9 being for example able to 
slide, accompanied by the intermediate washers 20 and 21, with respect to 
the washer 19 and to the contact surface 27 of the lug 15, which are 
secured to the bolt 16, the shank of the latter moving along the hole 13. 
Since the temperature variations are less great with the fluid chamber 2 
than with the fluid chamber 1, it is not necessary, in the example 
described, to make provision for any possibility of sliding of the lugs 8 
and 9 in the longitudinal direction of the fluid chambers.