FR2695990A1 - Tube for heat exchanger with mechanical assembly and heat exchanger thus obtained. - Google Patents

Abstract

The invention relates to a heat exchanger tube and the resulting heat exchanger. The tube (10) comprises a body (12) delimited by a tubular wall and extended by at least one end (14) suitable for being introduced into a hole (26) of a manifold plate (24) with the interposition of a seal compressible sealant (32), the end (14) of the tube being transformed, for example by turning the wall over, to have a wall thickness (e ') greater than the wall thickness (e) of the body of the tube, which makes it possible to increase the mechanical resistance of the end (14) to ensure, without deforming, the compression of the seal. Application in particular to heat exchangers for motor vehicles.

Description

Tube for mechanically assembled heat exchanger and heat exchanger

  heat thus obtained The invention relates to a tube suitable for forming part of a heat exchanger, in particular for a motor vehicle It

  also relates to a heat exchanger comprising such tubes.

  There is already known a heat exchanger tube comprising a body delimited by a tubular wall and extended by at least one end adapted to be introduced into a hole of a collecting plate, also called a plate with holes, with interposition

  a compressible seal.

  From a plurality of tubes of this type arranged in parallel, a beam is formed which is generally assembled with two collector plates, each of which is connected

to a water box wall.

  A heat exchanger of this type is used in particular in the automotive industry to form either a radiator for cooling a motor vehicle engine, or a

  passenger compartment heating radiator.

  The tubes of the bundle are usually traversed by a fluid used for cooling the engine, for example water with antifreeze added, while a flow of air sweeps

the bundle tubes.

  Because each end of the tube is received in a hole

  a collector plate with the interposition of a compressed gasket

  sible, we obtain a "mechanically assembled heat exchanger" as opposed to a "brazed heat exchanger", in which the ends of the tubes are brazed on the

collector plates.

  In mechanically assembled heat exchangers, it is necessary that each end of the tube has sufficient mechanical strength to ensure compression of the joint, without this end deforming, which would cause a loss of tightness in the connection area of the tube end

and the collector plate.

  It is known, in particular for tubes of oval or elliptical section, to increase the resistance of the end of the tube by

  bringing this end to a circular shape.

  This solution not only requires additional operations.

  but requires the use of a manifold plate with circular holes, which does not optimize the size of

the heat exchanger.

  It is also known to insert, into the end of the tube, a

  ring or spacer used to reinforce it.

  This solution also requires additional mounting operations and applies more particularly to ends of circular shape, hence the same drawbacks as those mentioned previously. Furthermore, this latter solution leads to pressure drops on the circulating fluid.

in the heat exchanger.

  It is therefore one of the objects of the invention to provide

  a heat exchanger tube to avoid inconvenience

above mentioned.

  It is also an object of the invention to provide such a heat exchanger tube whose end has a resistance

increased.

  It is also an object of the invention to provide such a heat exchanger tube whose tube end may have

  different shapes, circular or non-circular.

  The invention provides for this purpose a heat exchanger tube of the type mentioned above, in which the end of the tube is transformed to have a greater wall thickness

  than the wall thickness of the tube body.

  The end of the tube thus has a thickness greater than that of the tube before transformation, which increases its resistance.

  In a first embodiment of the invention, the extreme

  mite of the tube has a double wall obtained by inversion

  of the wall of the tube over a limited length.

  This reversal can be obtained by using several punches of appropriate shape gradually causing the reversal

  from the wall to the outside of the tube.

  The thickness of the double wall thus obtained is greater than or

  equal to twice the thickness of the wall of the tube body.

  In a second variant embodiment of the invention, the end of the tube results from a reduction in the section of the tube relative to the section of the body of the tube, leading to an increase in the thickness of the wall of the tube to its transformed end. This reduction in section can be obtained by inserting the end of the tube into one or more rings with a conical entry having the effect of tightening the end section of the

  tube and gradually increase the thickness of its wall.

  In this second embodiment of the invention,

  the thickness of the wall of the transformed end is general-

  less than twice the thickness of the wall of the tube body. To allow the transformation of the end of the tube, the latter is formed in a deformable metallic material, by

  example in aluminum or aluminum alloy.

  In another aspect, the invention relates to a heat exchanger comprising a multiplicity of tubes as defined above, the respective ends of which are assembled

  mechanically to at least one header plate.

  The invention relates in particular to a heat exchanger comprising a collector plate provided with holes surrounded by a collar, said collector plate receiving a seal with a multiplicity of compressible collars capable of sealing between the ends of the tubes and the collars, and in which the thickened ends of the tubes are in contact

compressible collars.

  In the description which follows, given only by way of example,

  reference is made to the appended drawing, in which: FIG. 1 is a partial view in longitudinal section of a

  heat exchanger tube according to the first embodiment

  mentioned above; Figure 2 is a partial sectional view of the tube of Figure 1 into the end of which is inserted a processing tool; Figure 3 is a partial sectional view of a heat exchanger comprising a multiplicity of tubes according to Figure 1;

  Figure 4 is a partial sectional view of a sample tube.

  heat gor according to the second embodiment above

  tee; and Figure 5 is a partial sectional view of the tube of Figure 4, the end of which is being transformed by a ring. We first refer to Figure 1 which represents a tube

  intended to be part of a heat exchanger and

  nant a body 12 delimited by a tubular wall and extended by at least one end 14 The latter is transformed by inverting the wall of the tube towards the outside of the latter over a limited length 1 Over the entire length 1, the end 14 has a double wall having a thickness e 'greater than or equal to 2 e, e representing the thickness of the wall of the body of the tube, which is also the thickness of the end of the

tube before transformation.

  The transformation of the end 14 can be obtained by successively using several punches of suitable shape

  causing the wall to gradually reverse.

  FIG. 2 shows, by way of example, a punch 16 used in an intermediate phase of transformation This punch 16

  has, in the example, a head 18 of generally truncated form

  that allowing to flare the end edge 20 of the tube before folding it down then as shown by the arrows F by others

punches (not shown).

  The heat exchanger shown in Figure 3, to which we now refer, comprises a header plate 24 through which are formed a multiplicity of holes 26

  each of which is surrounded by a collar 28.

  In each of the holes 26 is introduced the end 14 of a tube as defined above, the tubes 10 forming a bundle of parallel tubes which pass through a multiplicity of fins 30. The collecting plate 24 receives a gasket 32 comprising , in correspondence of the collars 28 of the plate

  manifold 24, a multiplicity of compressible collars 34.

  Each collar 34 of the seal is thus compressed in the annular space between the end 14, of thickness e ', of a

  tube 10 and a collar 28 of the collector plate 24.

  The body 12 of the tube can have a circular or non-circular section and, similarly, the section of the end 14 can be

circular or non-circular.

  The collector plate 24 preferably has a rectangular shape and it includes, on its periphery, a folded edge 36 forming a groove for receiving a peripheral bead 38 of the joint 32 The groove thus formed receives a peripheral rim 40 forming part of a wall 42 water box This rim 40 is held by the folded edge 36 which compresses the bead 38

of the joint.

  In the embodiment of Figure 4, to which we now refer, the body 12 of the tube 10 is extended by at least one end 44 which is transformed to have a wall thickness greater than the wall thickness of the body

of the tube.

  The end 44 results from a reduction in the cross-section of the tube relative to the cross-section of the body of the tube, which leads to an increase in the thickness of the wall of the tube at its transformed end. The end 44 thus has a wall thickness e 'which is greater than the wall thickness e of the body 12, while generally being less than twice the thickness e of the

body of the tube.

  This reduction in section can be applied to sections of circular or non-circular shape. It is obtained by forcibly introducing the end of the tube into one or more rings 46 as shown in FIG. 5 The ring 46 has a frustoconical entry 48 and is extended by a cylindrical passage suitable for transforming the end of the tube When the latter is forced into the ring 46, the wall

  end narrows and its thickness gradually increases-

is lying.

  In most cases, it is necessary to use several rings to gradually reduce the section of the tube

  and gradually increase its wall thickness.

  The end 44 of the tube 10 in FIG. 4 can be introduced into a hole in a collector plate in the same way as

  the end 14 as shown in FIG. 3.

  Reducing the end section of the tube has the other

  advantage of reducing the size of the collector plate.

  To allow the transformation of the end of the tube, it

  this is made of a deformable metallic material, for example

  made of aluminum or aluminum alloy.

  The end of the tube may have a circular or non-circular shape, for example oval or elliptical, which is not

  necessarily the same as that of the body of the tube.

  Tubes can be transformed either individually-

  each tube, preferably preferably simultaneously

  all the ends of the tubes already grouped in bundle.

  The assembly of the bundle is then carried out in a manner known per se to form a heat exchanger which can be used in particular.

on motor vehicles.

Claims (7)

Claims   1 heat exchanger tube, comprising a body (12) delimited by a tubular wall and extended by at least one end (14; 44) suitable for being introduced into a hole (26) of a collecting plate (24) with interposition of a joint   compressible seal (32), characterized in that the end   mite (14; 44) of the tube is transformed to have a wall thickness (e ') greater than the wall thickness (e) of the body of the tube.   2 heat exchanger tube according to claim 1, characterized in that the end (14) of the tube (10) has a double wall obtained by inverting the wall of the tube on a limited length (1).   3 heat exchanger tube according to claim 2, characterized in that the thickness (e ') of the double wall is greater than or equal to twice the thickness (e) of the wall of the body (12) of the tube (10).   4 heat exchanger tube according to claim 1, characterized in that the end (44) of the tube (10) results from a reduction in the section of the tube relative to the section of the body (12) of the tube, leading to an increase in   the thickness (e ') of the wall of the tube at its transformed end   mee. Heat exchanger tube according to claim 4, characterized in that the wall thickness (e ') of the transformed end (44) is less than twice the thickness of   wall (e) of the body (12) of the tube (10).   6 heat exchanger tube according to one of claims 1   to 4, characterized in that it is formed from a metallic material   deformable, for example aluminum or aluminum alloy.   7 Heat exchanger comprising a multiplicity of tubes   (10) according to one of claims 1 to 6, the ends of which   respective (14; 44) are mechanically assembled to a plate collector (24).   8 Heat exchanger according to claim 7, comprising a collecting plate (24) provided with holes (26) surrounded by a collar (28), said collecting plate receiving a seal (32) with a multiplicity of compressible collars (34 ) suitable for sealing between the ends (14) of the tubes (10) and the collars (28), characterized in that the thickened ends (14) (e ') of the tubes (10) are in contact compressible collars (34).