FR2767913A1 - HEAT EXCHANGER COMPRISING TWO CONNECTED COLLECTORS AND COMMUNICATING BETWEEN THEM THROUGH FLAT PIPES BORDERED WITH SIDE PARTS - Google Patents

Abstract

The invention relates more specifically to a means preventing bulges or bends in the pipes of such an exchanger under internal pressure. The flat pipes (3) between the collectors (2) are traversed by a first fluid and bordered by two lateral pieces. (5) holding and protection, which extend parallel to the two outer pipes (3). Fins (4) are arranged and fixed between the adjacent pipes and between the outer pipes and the side pieces (5), so as to define a flow path for a second fluid. In order to avoid deformation and simplify the manufacture of the exchanger, the axial ends of the side pieces (5) are not fixed to the manifolds (2) in the lengthwise direction of the latter. Can be used as a radiator or as a condenser the air conditioning system of an automobile.

Description

The invention relates to a heat exchanger comprising two collectors

  for a first fluid, which are connected and communicate with each other by flat pipes extending approximately parallel to one another, as well as two side pieces extending parallel to the respective flat pipes located furthest to the outside, with arrangement, between the neighboring flat pipes and between the lateral pieces and the respective adjacent flat pipes, fins fixed to the flat pipes and to the lateral pieces and forming a path

  flow for a second fluid.

  Such exchangers are preferably used as an air / coolant heat exchanger in the cooling circuit of a motor vehicle, in which case they are generally called "radiator". Such an exchanger can also be used as a condenser in the air conditioning system of a motor vehicle. In the case of an exchanger of this type, which is known for example from document EP 0 102 715, a fluid to be cooled, for example, flows in a first manifold in which it is distributed over a plurality of parallel flat pipes. These open into a second collector in which the fluid emerging from the

  flat pipes come together before coming out of the second neck

  reader. Between the flat pipes are arranged ai-

  le.tes, shaped in particular in a zigzag or wavy shape, which are connected to the flat pipes for the transmission of heat. Flat pipes, usually placed in a plane, are exposed by their fins to a flow of air which is generally oriented perpendicular to this plane, so that an effective heat exchange can

take place.

  High pressures can prevail in a cooling circuit and pressure peaks similar to pulses can occur in particular, which may cause, in the case of flat pipes in which only an interior space is formed for the flow, the formation of bulges on these pipes or the bulging of these. Flat pipes usually

  employees are made from a flat material at the

  what is imparted, by adequate deformation by

  folding, a closed tubular profile in cross section, the-

  which is sealed by welding together

  folded and joined longitudinal edges. A bulge-

  caused by high pressures can cause

  cracking of the welded joint of these pipes, so the endomna-

  hose and therefore also the exchanger.

  In order that high pressure cannot produce such a large bulge in the flat pipes, the latter must be reinforced on their outside. This

  function is also fulfilled by the fins - assu-

  rant first the transfer of heat between fluids - since the fins provide support

  mutual neighboring flat pipes on the longitudi-

nals exposed to the bulge.

  In order to also prevent a dangerous bulge on each of the two outermost pipes, i.e. those on the outside on both sides of the exchanger, again on the by means of the fins, side parts are provided which are

  co-ordinates the fins of the outer flat pipes

  born. So that the side pieces can transmit

  forces oriented along the length of the collars

  readers to these, they are set by their e:.: -

  axial hoppers to the collectors, at least as regards this longitudinal direction The side parts and the flat pipes heat up differently during the operation of the exchanger. Since this results in different expansions of the components, in particular in the direction of their axis, they must be movable relative to each other

  to others in this direction in order to avoid damage

  heat exchangers. In the case of the exchanger

  known above, there are provided for this purpose arms of hand-

  yours which are fixed at one end to the collector concerned and kept axially sliding by their other end on the corresponding side piece. In this way, the side pieces can be moved in

  the direction of their axis, so that variations in

  compared to flat pipes can be compensated

sées.

  The installation of these holding arms requires additional operations in the manufacturing and the execution of the assembly must also be relatively precise in order to be able to guarantee an axial guidance preventing

  jamming during axial movement of the parts la-

  teral. It follows that the known heat exchanger is

  relatively expensive to manufacture.

  The object of the present invention is to provide a

  exchanger, of the type mentioned at the beginning, by means of

  simple constructions, so that

  can be manufactured simply therefore economically.

  According to the invention, parDant an exchanger as defined at the beginning, this is obtained by the fact that the axial ends of the side pieces are

  free vis-à-vis the collectors in the direction of lon-

cheer of these.

  The invention is based on the general concept of not attaching the axial e: rits of the side pieces to the coordinated manifold, at least as regards (in the sense of) the axial direction of the manifold concerned, so that these ends are

  freely movable in said direction at least.

  The invention exploits the surprising observation that fixing the lateral parts to the manifolds, as regards the axial direction of the collector concerned, is not necessary to effectively prevent

  the harmful bulge of the flat pipes.

  As there is no attachment of the lateral parts to the manifolds in the exchanger according to the invention, the manufacture and the finishing of the exchanger can be

simplified considerably.

  The manufacture of the exchanger can be simplified

  even more so when, in accordance with a mode of

  timely reading of the exchanger according to the invention, the

  axial ends of the side pieces are applied

  quer, especially during assembly, transverse-

  lying in the longitudinal direction of the collector

  given, against this collector. During the cassette assembly "(see explanation in the following), the

  flat pipes, mutually aligned and spaced, are trapped

  boxed as a complete sub-assembly in the holes prepared for this purpose in the collectors. Thanks to the proposed arrangement, the application of the axial ends of the side pieces against the collectors creates

  a stop which prefixes the optional nesting depth

  male pipes in the manifolds.

  During the above-mentioned cassette assembly ("Kassettierung"), the side pieces, the flat pipes and the interposed fins are aligned parallel between

  them. It should be noted in this respect that the fins in par-

  are produced in a relative tolerance zone

  relatively wide, so that relative position differences

  tively large can occur, especially for the outermost pipes, given the large number of pipes juxtaposed with the fins placed between them. So that the pipes can be fitted into the holes prepared for them in the manifolds, the prepared sub-assembly, similar to a block and composed of the side pieces, flat pipes and fins, is compressed laterally, until the desired spacings and positions are obtained. During this operation, the side pieces are used to transmit the compression forces through a large surface to the fins.

  located outside the outer pipes, with the re-

  result that the fins - which are very thin - can

  be deformed without being damaged.

  The use of lateral parts in the form of pipes having in cross section a rigid profile at the

  bending, in accordance with another development of the in-

  vention, allows a uniform transmission of forces to the fins, in order to avoid irregular deformations of

  these. A particularly gentle deformation is obtained.

  the various components during the cassette assembly when side parts having

straight section a closed profile.

  Another feature provides that the side pieces are made of a material drilled with holes or provided with slots. The use of side pieces with slots or holes allows simple attachment of

  holding or damping means on these parts.

  Yet another characteristic of the invention provides that manifolds, flat pipes, parts

  side and the fins are made of the same mas-

  riau, in particular aluminum or an aluminum alloy

  nium. The heat exchanger thus obtained is particularly suitable for

especially good for recycling.

  Other features and advantages of the

  vention will emerge more clearly from the description

  which will follow from several nonlimiting exemplary embodiments, as well as from the appended drawings, in which: - Figure 1 is a top view of a heat exchanger according to the invention; - Figure 2 is a detail showing on a larger scale the area of an axial end of a side piece; and

  - Figure 3 shows different forms of reaction

  sizing of profiles for the side pieces used

  in the exchanger according to the invention.

  As shown in Figure 1, a heat exchanger 1 according to the invention comprises two (pipes) collectors 2 approximately parallel, in which flows for example the coolant from the cooling circuit of a motor vehicle. The collectors 2 are connected and communicate with each other by

  pipes 3 parallel to each other, so that a

  coolant can be established from a manifold 2 through the pipes 3 to the other manifold 2. The pipes 3 are hereinafter called "flat pipes" because they have a rectangular cross section whose relationship from large to small east side

relatively high.

  To the flat pipes 3 are fixed fins 4 which are shaped in a zigzag in the embodiment example according to FIG. 1. Corrugated fins are also usable. The fins 4 serve to dissipate the heat transmitted by the coolant to the flat pipes 3. In addition, they connect the neighboring flat pipes 3 to one another and provide mutual support for

  counter the bulge of these pipes under the effect of

  High coolant ions.

  To the outer fins 4 flat pipes 3 located furthest to the outside, are fixed, parallel to these

  pipes, side pieces 5 which each have in particular

  bind for the function of opposing bulges in the external pipe 3 concerned. The side pieces 5 serve

  wind protection for the hands against ai-

  lettes 4 with sharp edges lying outside.

  If a high pressure is created in the cooling circuit, the rectangular sections of the flat pipes 3 or, more precisely, their long sides, bulge in taking a convex shape directed towards the outside. The expansion thus produced on a single pipe 3 is small, but the expansions of the plurality of pipes of the exchanger add up. It should be noted in this regard that the axial ends of the flat pipes 3 are fixed in the manifolds 2, so that the pipes only bend outwards in the median zone between the collectors 2. The bending or the bending towards the outside is greatest on the outermost pipe 3, so the risk of cracking as a result of bulging of the outside pipe is also greatest in this

  zoned. The forces producing a bulge of a pipe ex-

  térieur 3 and the forces producing the bending towards the outside of such a pipe are distributed by the part

  lateral 5 adjacent on the different segments of the

  lette 4 concerned and this over the entire length of the pipe 3

  in question, which prevents bulging and sagging-

excessive amounts of this hose.

  As shown in the detail in Figure 2, the axial ends of the side pieces 5 are not connected to the collector 2 coordinated. Therefore, each part 5 can perform relative movements in any direction relative to this collector, without constraints being established between these two components. Such relative movements can occur especially when

  thermal expansion because the side piece 5 pre-

  regularly feels lower temperatures than those prevailing inside the pipes 3 for example. The reason why, in accordance with the invention, the side pieces 5 also fulfill their function without an attachment or a fastening to the manifolds 2, namely to prevent a bulging and a dangerous bending of the external pipes 3, probably lies in the fact that in the area close to the manifold 2, due to the fixing in this manifold of the flat pipes 3, there is, in any case, no displacement or only a slight displacement of the side pieces 5 in the direction of the axis of the manifolds 2 , so that there are no significant forces at this location which would be transmitted from the side piece 5 to the manifold 2. A dangerous bulge and deflection of the pipes 3 can therefore be prevented by the mere transmission of forces , through parts

  lateral, with a large number of fins 4.

  So that, also during cassette assembly, relatively large compressive forces can be uniformly applied to the fins 4 - which are sensitive - via the parts 5, rigid flexural sections are used for the latter. FIG. 3 shows by way of examples some preferred embodiments, designated respectively by A to

  K, such rigid sections to bending.

  Examples A to C relate to closed sections which are remarkable for a particularly high bending stiffness. Profile C also has holes 6 allowing for example the attachment of additional holding means, allowing for example a better positioning of the heat exchanger 1 in

the engine compartment.

  Examples D to K relate to profiles having a high flexural rigidity due to their shape and suitable for compressing the block composed of the lateral parts, flat pipes and fins during cassette assembly. The open sections J and K again have holes 6 used for fixing

other components.

  The use of a side piece 5 provided, in accordance with the invention, with a rigid profile at the

  bending, allows even with relative tolerance zones

  large in the manufacture of fins,

  think of spacing differences - due to tolerances -

  between the flat pipes 3. Consequently, to manufacture the heat exchanger according to the invention, it is also possible to use fins 4 relatively inexpensive, which makes it possible to make the manufacture of

  the overall more economical exchanger.

  The application of a uniform load per unit area via the side pieces 5 on

  the fins 4 is advantageous not only to compensate

  ser spacing differences due to tolerances between the flat pipes 3, but also when brazing the fins 4 to these pipes and to the side pieces 5, as well as when brazing the pipes 3 to the manifolds 2. During these operations , there is a relatively significant heat development, which can also

  cause expansion, deformation and decay

  lages of the components maintained positioned one by

  compared to others. Such changes in position can

  can be avoided by applying a prestress

  through the side pieces 5.

Claims (6)

CLAIM $   1. Heat exchanger comprising two collectors for a first fluid, which are connected and communicate with each other by flat pipes extending roughly parallel to each other, as well as two side pieces extending parallel to the side of respective outermost flat pipes with arrangement between neighboring flat pipes and between   the side pieces and the adjacent flat pipes respectively   tifs, fins attached to flat pipes and parts   lateral and forming a flow path for a se-   fluid cond, characterized in that the axial ends   side pieces (5) are free vis-à-vis the collectors   teurs (2) in the direction of the length thereof.   2. Heat exchanger according to claim 1, characterized in that the axial ends of the lateral parts (5) are applied, in particular during assembly, transversely to the direction   longitudinal of the coordinated collector (2), against this collar   reader. 3. Heat exchanger according to claim 1 or 2, characterized in that the side pieces (5) are made in the form of pipes having a cross section a rigid bending profile.   4. Heat exchanger according to claim 3, characterized in that the side pieces (5) are   made with a closed profile in cross section.   5. Heat exchanger according to one of claims   1 to 4, characterized in that the side pieces (5) are made of a material drilled with holes or provided with slots. 6. Heat exchanger according to one of rever.dications 1 to 5, characterized in that the collectors (2), the   flat pipes (3), the side pieces (5) and the   lettes (4) are made of the same material, in particular   bind aluminum or aluminum alloy.