EP1146310B1 - Improvements related to multitubular shell-type heat exchangers and method of producing the same - Google Patents

Abstract

The heat exchanger (1) for an internal combustion engine has a casing (2) defining an axial cylindrical cavity (3). A matrix has multiple tubes extending in the chamber along the axis. The casing is formed of a section of a profile and does not have fixings for the end caps and-or matrix. The caps are fixed to the matrix and have radial sealing. The sealing faces of the casing are not machined. An Independent claim is also included for a manufacturing process for the heat exchanger.

Description

The present invention relates to improvements made to the shell-and-tube heat exchangers and methods of manufacturing these exchangers.

The invention is particularly applicable to heat exchangers between a first fluid flowing in a plurality of tubes forming a multitubular bundle, and a second fluid circulating around the tubes, in a delimited cylindrical cavity by a hollow body (or calender) in which the bundle of tubes extends; Typical applications: heat exchangers, gearboxes, inverters, compressors, hydraulic units ...; in this type of known exchanger, the transfer of thermal energy between the hot source and the cold source is carried out in particular by conduction through the wall of the tubes; to obtain a transfer flow of energy (and / or a heat exchange coefficient) sufficient, the tubes are made in a material having a high thermal conductivity, such as a metal alloy with base of copper, aluminum, nickel, titanium or stainless steels.

The invention applies in particular to such exchangers comprising two tubular plates generally disc-shaped, which are pierced with a plurality of holes, and in which each of the two ends of each of the tubes is engaged in one of the orifices of a tubular plate and is secured in a sealed manner this plate in particular by soldering, welding or swaging.

The tubular bundle generally comprises, besides the tubes and the plates tubular end, baffles for guiding the flow of the second fluid inside the hollow body; these baffles are usually basically formed by thin plates extending transversely to the tubes and parallel to the end tube plates, are evenly spaced along tubes and close part of the cross section - usually circular - hollow body, to guide the second fluid.

Such exchangers generally comprise, in addition, at each of its two longitudinal ends, a cap (water box) covering respectively a said tubular plates, and allowing either the connection of the exchanger to two conduits (external to the exchanger) for transporting the first fluid, ie the guiding of this fluid in the case of a cap "blind", ie devoid of connection to a external conduit.

The hollow body is provided with an inlet orifice of the second fluid in the said cavity as well as an outlet of this fluid; the hollow body is usually consisting of a generally tubular piece provided with each of its two longitudinal ends of an annular flange; each flange is pierced with several orifices extending along the longitudinal axis of the exchanger and receiving screws - or similar fastening members - for securing to the body, in a sealed manner, at least one of the tubular plates and the two caps.

While for large heat exchangers, especially for larger large diameter greater than or equal to 0.5 meters, it is usual to build the body by rolling of a ferrule and welding of the flanges, the body of the small heat exchangers (in greater diameter less than 0.25 meters) are usually manufactured by molding (without pressure) of a metal alloy, the body and the flanges being molded in one piece; this technique has disadvantages: the face internal body must be machined along its entire length to have a roughness and a geometric quality compatible with the use made of it; the faces outer flanges must also be erected; these molded parts frequently have defects in their mass resulting in porosity incompatible with the waterproof wall function they must perform; in addition, these defects can only be validly checked after mechanical machining (bore, turning ...); it is thus necessary to discard expensive parts; the pressure-free molding technique (in sand molds) also prevents to make thin walls.

Furthermore, it has been proposed in patent FR 623 803 a heat exchanger multitubular whose body consists of an ordinary piece of pipe and is devoid end flanges.

An object of the invention is to propose such exchangers which are improved, as well as a method of manufacturing these exchangers which make it possible to reduce the cost.

According to a first aspect, the invention consists of a method of manufacturing such exchangers, in which a blank of the hollow body is produced by extrusion of a material for forming a hollow section, and in which a section of said section is cut shaped; this method makes it possible to obtain a blank delimiting a cylindrical cavity of generally circular section whose geometry and surface state are good enough to avoid the need for subsequent machining of the inner face of the wall of the body even when the end of this wall forms a scope for joints; using a homogeneous material and thanks to the pressurization of the material allowing its passage through the die, we obtain a blank free from defects (micro cavities), and therefore non-porous.

In particular, when an aluminum-based alloy is used as the material, it is It is preferable to proceed with a heat treatment (soaking) of the profile in order to improve the mechanical strength; this allows a body sketch hollow, whose tubular wall is thin, while being sufficiently resistant: for operating pressure of the order of 1 to 100 bar, tests have shown that a wall whose thickness is such that its ratio to the radius of the cross-section of the cylindrical cavity of the body is located in a range of 1% to 20%, is satisfactory; alternatively, other materials, in particular metals, preferably non-ferrous, or plastics may be used.

According to another aspect, the invention consists in proposing such exchangers the hollow body consists essentially of one or more sections of profile extrusion molded, and does not have an end flange.

Preferably, the profile (or contour) - in a cross section - external of the external face of the hollow cylindrical body is not entirely circular: this profile external may have at least one rectilinear segment that is tangent to a first circle concentric to a second circle corresponding to the transverse profile of the inner face of the wall and / or the body; to this rectilinear segment of the external profile corresponds to a flat part of the external face of the hollow body; this flat face thus extends preferably tangentially to a cylinder coaxial with the hollow body, in a part of the body wall which has said inlet and outlet ports said second fluid; this facilitates the mechanical connection to the hollow body of two external conduits for transporting this fluid; preferably this part of the wall of the body, which extends under (opposite) this flat face, is provided with a thickness greater than the average thickness of the tubular wall of the body; this results in a wide rib (or longitudinal boss) which facilitates the realization of said orifices under tapped holes adapted to receive a screw connection for the connection of transport ducts of the second fluid.

In addition, the transverse external profile of the body may preferably comprise other rectilinear segments, to which correspond salient ribs (or many recessed grooves) formed on the outer surface of the hollow body and extending longitudinally; in particular these ribs or grooves can marry an I, V or U profile and can be used to fix the body (and the exchanger) on a support, and / or to the connection connection connection of the transport conduits of the second fluid (Figure 9).

The exchangers according to the invention do not comprise rigid connection means between the hollow body and the tubular bundle, the mechanical connection between these elements resulting essentially from the contact (support) forces acting between these two parts through two first sealing members such as two seals O-rings, which are flattened (compressed) between two cylindrical bearing faces (or carried) respectively on each of these two pieces; in the absence of these sealing members, the beam can freely slide in the body cavity; in the presence of these sealing members the beam can slide in the cavity under the action of a sufficient effort, especially under the action of the elongation of tubes of the bundle, due to their thermal expansion; each of said bodies Sealing is usually housed in an annular groove; preferably these grooves are provided on the outer face of the tubular plates; this avoids the realization (more expensive) grooves on the inner face of the wall of the hollow body; it then only requires the completion of a chamfer at its end (s) internally (s), which allows to introduce by sliding a beam whose plate tubular is provided with the seal without damaging the seal and facilitating its crushing.

• permettre d'obtenir une étanchéité satisfaisante par appui d'un organe d'étanchéité sur la face interne de cette cavité ;
• limiter le jeu entre la face interne du corps et le faisceau ;
• éviter le coincement du faisceau lors de son insertion dans le corps ;
• éviter d'endommager les organes d'étanchéité par frottement sur la face interne de la cavité, lors du montage du faisceau par coulissement dans la cavité.

The invention thus rests in part on the fact that, despite the presence of striations and roughnesses on the internal face of the body, resulting from the extrusion thereof, and despite the deformations (difficult to control) of the profile during its cooling, which are further accentuated when the profile is not of constant thickness, it is possible to obtain by extrusion a hollow body delimiting a cylindrical cavity whose geometry is sufficiently precise and regular and whose roughness is sufficiently low, without that it is necessary to machine this one, for, at the same time:

• allow to obtain a satisfactory seal by pressing a sealing member on the inner face of this cavity;
• limit the clearance between the inner face of the body and the beam;
• avoid jamming the beam when inserted into the body;
• avoid damaging the sealing members by friction on the inner face of the cavity, when mounting the beam by sliding in the cavity.

In the exchangers according to the invention, the caps are fixed on the plates tubular beam, without being fixed on the hollow body; this assembly allows, in providing for a clearance between the body and the caps, the free differential expansion of the main parts and assemblies constituting the exchanger (body / cap / beam); preferably each cap is respectively attached to one or other of the plates of the bundle, by means of a first rigid connection means provided in part center of the outer face of the plate, such as a tapped hole, and through a means guide and support which is provided in the central part of the cap, such as a socket (or insert), which is adapted to receive a second rigid connection means - such as a screw complementary to said first rigid connection means.

At this central fixation of the cap on the tube plate of the beam is preferably associated with a second annular sealing member which is preferably in support (radial) on two cylindrical faces respectively provided on the plate on the one hand and on the cap on the other hand, the sealing member being slightly crushed (compressed) between these two faces arranged coaxially and facing one another; in arranging these two faces respectively at each end of the plate tubular on the one hand and the cap on the other hand, we obtain a commitment of these bearing faces (span) of seal with the seal to form a tight assembly, in exerting a relatively small effort that may result from reciprocal engagement said rigid connection means provided in the central part of the cap and the plate, in particular by screwing a single screw; these efforts are far less than those to be exerted to ensure a tight connection by a crushed O-ring between two flat parallel support faces, as is the case in the flange connections.

According to a preferred embodiment, each of said two plates tubular end comprises a groove receiving said first sealing member with the hollow body, and comprises a countersink opening on its outer face and carrying said second sealing member with the associated cap, and the length of the body hollow is greater than the distance separating the two grooves respectively provided on each of the tube plates and is less than the distance separating the two counters; therefore, the first sealing members are (after assembly) arranged recessed from the ends of the body and the second sealing members are disposed beyond the ends of the body, that is to say outside of it; he in the event of a fault in one of these sealing members producing a leak of one or the other of the two fluids, the leakage current flows outside the body and is therefore identifiable; in addition, no mixing of these two fluids can result from such default.

This "radial" design of the sealing means between the tube plate and the cap allows to use, for the realization of the cap, a resistance material mechanical medium and thin, such as a plastic case optionally reinforced with mineral fibers preferably, the caps are molded and integrate (in one piece) said sleeve (or insert) allowing their attachment central on the tube plate.

La figure 1 illustre en vue d'extrémité un tronçon de profilé extrudé formant un corps d'échangeur selon l'invention.

La figure 2 est une vue en coupe longitudinale partielle du corps de la figure 1.

La figure 3 est une vue en coupe longitudinale d'un échangeur selon l'invention, qui est équipée de deux calottes d'orientation axiale (longitudinale) ; sur cette figure, les tubes du faisceau ne sont pas représentés pour en faciliter la compréhension.

La figure 4 est une vue d'extrémité du faisceau de tubes de la figure 5,

La figure 5 illustre en vue en coupe longitudinale un faisceau multitubulaire d'un échangeur selon l'invention qui comporte un corps en deux parties séparées et qui permet de réaliser un échange de chaleur entre un premier fluide et deux deuxièmes fluides ; à cet effet le faisceau est équipé d'une plaque tubulaire intermédiaire disposée entre les deux plaques tubulaires d'extrémité et comportant deux gorges destinées à recevoir deux joints pour l'étanchéité avec chacune des portions de corps.

Les figures 6 et 7 illustrent respectivement en vue en coupe longitudinale et en vue d'extrémité, un mode de réalisation d'une calotte d'un échangeur selon l'invention ; la figure 6 est une vue selon VI-VI de la figure 7 qui est elle-même une vue d'extrémité de la figure 6. Cet exemple montre la possibilité d'intégrer d'autres éléments tels que bouchon de vidange, anode de zinc, grâce à la présence d'un orifice radial 200.

La figure 8 illustre schématiquement en vue en coupe longitudinale une calotte coudée d'un échangeur selon l'invention.

La figure 9 illustre en vue en coupe transversale schématique un mode de réalisation du raccordement des orifices d'entrée et de sortie du corps à des conduits externes.

La figure 10 illustre en vue d'extrémité la fixation d'un échangeur par deux pattes 80 coudées en forme de L et dont une extrémité forme un crochet venant en prise dans une rainure du corps.

Other advantages and features of the invention will be understood through the following description which refers to the accompanying drawings, which illustrate without any limiting nature of the preferred embodiments of the invention.

FIG. 1 illustrates, in end view, an extruded profile section forming an exchanger body according to the invention.

Figure 2 is a partial longitudinal sectional view of the body of Figure 1.

Figure 3 is a longitudinal sectional view of an exchanger according to the invention, which is equipped with two caps of axial orientation (longitudinal); in this figure, the tubes of the beam are not shown to facilitate understanding.

FIG. 4 is an end view of the tube bundle of FIG. 5,

FIG. 5 illustrates, in longitudinal sectional view, a multitubular beam of an exchanger according to the invention which comprises a body in two separate parts and which makes it possible to exchange heat between a first fluid and two second fluids; for this purpose the beam is equipped with an intermediate tubular plate disposed between the two end tube plates and having two grooves for receiving two seals for sealing with each of the body portions.

Figures 6 and 7 respectively illustrate in longitudinal sectional view and in end view, an embodiment of a cap of an exchanger according to the invention; FIG. 6 is a view along VI-VI of FIG. 7 which is itself an end view of FIG. 6. This example shows the possibility of integrating other elements such as drain plug, zinc anode due to the presence of a radial orifice 200.

Figure 8 schematically illustrates a longitudinal sectional view of a bent cap of an exchanger according to the invention.

FIG. 9 is a diagrammatic cross-sectional view of an embodiment of the connection of the inlet and outlet ports of the body to external ducts.

Figure 10 illustrates in end view the attachment of an exchanger by two lugs 80 bent L-shaped and one end forms a hook engaging in a groove of the body.

With reference to FIGS. 1 to 5 in particular, exchanger 1 consists essentially in a body 2 delimiting a cylindrical cavity 3 of longitudinal axis 4, a bundle 5 of tubes 6 extending into the cavity 3, parallel to the axis 4, and of which the ends are attached to two tubular plates 7, 8, and two caps 9 and 10 of connection.

The invention is particularly suitable for oil coolers, water coolers, fuel, air equipping the engines of boats or trucks, the gearboxes, inverters, reducers, compressors, hydraulic units ..., and in which the cold source is freshwater or seawater; the water enters according to the arrow 11 in the cap 10, circulates in the tubes 6 and is collected at the outlet of these in the cap 9 for its evacuation according to the arrow 12.

As illustrated in FIGS. 1 and 2, the body 2 has an internal face 13 cylindrical of circular section and axis 4; at each longitudinal end of the body 2, a chamfer 14, 15 extends the unmachined cylindrical face 13 to facilitate the introduction into the cavity of a tubular plate equipped with an O-ring peripheral as marked 16, 17 figure 3.

The wall 20, 33 of the body 2 is radially pierced with two orifices 18, 19 respectively allowing the inlet (arrow 13) and the outlet (arrow 14) of the fluid to cool.

As illustrated in FIG. 1, the transverse profile of the external face 21 of the wall 20 consists of a plurality of rectilinear segments: segments such as those marked 22 and 23 correspond to a longitudinal groove 24; segment 25 extending between the grooves 24 corresponds to a rib whose tail profile dovetail can be used to cooperate with a hook (shown in FIG. complementary shape for fixing the body of the exchanger to a support; the segments 26 to 30 correspond to a longitudinal tongue 31 likely to be breakthrough along the axis 32 for fixing the exchanger.

The body of FIG. 1 has a rib 33 whose thickness 34 can be close to 10 mm while the average thickness of the wall 20 is of the order of 2 to 3 mm when the body is made of aluminum alloy; this rib has the holes tapped 18, 19 of connection fitting to the circuit of the fluid to be cooled.

In the variant illustrated in FIG. 9, the transverse profile of the outer face 21 is essentially circular, with the exception of a protruding rib 33 in profile dovetail for fixing a fitting 36 equipped with an O-ring 37, for the connecting the body to fluid transport conduits.

The tubular bundle of FIGS. 4 and 5 comprises tubes 6 parallel to the axis 4 whose ends are sealingly attached in orifices 38, 39 respectively provided in the plates 7, 8; this beam has a plate intermediate tubular 40 parallel to the plates 7, 8 and provided at its periphery with two annular grooves 41, 42 each receiving an O-ring 43; the tubes 6 extend through this plate whose outer face is sealed, so that when this beam is housed in a body, the plate 40 and the joints 43 separate the cavity of the body in two parts, sealingly; this allows to cool a first second fluid circulating along the current lines marked 44 in the left part of the exchanger (Figure 5), and allows to cool a second second fluid flowing along the current lines 45 in the right part of the exchanger, without that these fluids mix.

As particularly shown in FIG. 5, the body of the exchanger can be constituted by two sections 2a, 2b aligned end to end without being secured to each other. the other.

As illustrated in particular in FIG. 3, the assembly formed by the beam tubular and by the caps 9, 10 is not fixed rigidly to the body 2: the connection between this assembly and this body results from the elasticity of the O-rings 16, 17 respectively housed in the grooves 46, 47 provided at the periphery of the plates 7, 8, and which were compressed upon introduction of the beam into the cavity; this non-rigid connection allows the rotation of the body 2, along the axis 4, around the beam 5; he For this purpose, it suffices to exert a sufficient torque to overcome the friction forces of the joints 16, 17 on the inner face 13 of the wall 20 of the body 2; preferably this link also allows the translation of the body 2 along the axis 4 around the beam 5, when a force greater than the friction of the seals 16, 17 is applied to the face 13, and thanks to an axial clearance 48 provided between the end (49 Figure 3) of the body and the end 50 the corresponding cap; this connection also allows the free expansion of the body without stress on the caps.

By providing such an axial clearance of sufficient value, it is not necessary to precisely machine the ends of the tubular body, whose perpendicularity with Axis 4 is not critical; it is enough to cut the profile then to realize the case the chamfers 14, 15.

Thus, each of the tubular plates 7, 8, 40 is in the form of a thick disc whose slice receives the seals.

FIG. 3 shows that the beam extends beyond each end length of the body, the length 51 of the beam being greater than that (52) of the body: at each end of the beam, a portion of each plate 7, 8 protrudes to the outside of the body; this outer portion of the plate 7, 8 comprises a counterbore annular peripheral 53, 54 opening on the outer face 55, 56 respectively of the plates 7, 8; each countersink receives an O-ring 57, 58 sealing (by radial support) between the periphery of the plate and the end cylindrical end 59, 60 caps 9, 10; each of these endpieces is provided with a chamfer 61 (FIG. avoid damaging the seal during tight fitting of the nozzle around the plate tubular equipped with the seal.

Each cap has a flared wall 62 extending the nozzle 59, 60 and extended by a second cylindrical nozzle 63 for connection to a non-duct represent.

In the variant shown in FIG. 8, the cap 9 has a central portion flared and bent wall 162 which connects the connecting end piece 163 (to a duct inclined relative to the axis 4) to the nozzle 59 of connection with the tube plate; sealing can be provided by a seal provided under the head of the screw.

The mechanical fastening of each cap on the respective tube plate is obtained by a screw extending along the axis 4 through a cylindrical sleeve 65 axis 4 integrated into the cap and on which the head 64 of the screw; the screw is screwed in a tapped hole 66 provided in the center of each plate 7, 8, and opening on the external side of it only.

When the cap is made of plastic (Figure 3) molded, it is preferable to provide a metal insert 67 in the sleeve 65 to support the clamping force of the screw; such an insert is not useful when the cap is cast in a metal alloy (Figures 6 to 8).

Figure 7 illustrates three radial arms 68 arranged at 120 degrees about the axis 4, which connect the central sleeve 65 to the flared wall 62 of the cap; the number and the form of the arms (sails) is adapted to the diameter and straining efforts of the cap.

In the case of the cap illustrated in FIGS. 3 and 6, the fixing screw is embedded in the fluid circulating in the cap.

The thin connecting arms 68 extend substantially radially from each other to the axis 4 along which the connecting sleeve 63 and the sleeve extend. cylindrical 65.

With reference to FIG. 5, the tubular bundle comprises baffles 69 annular disc-shaped, pierced in the middle for the central passage fluid 44, which are alternated with non-drilled disk-shaped baffles 70 in their middle and smaller diameter than the baffles 69 for the passage of the fluid between the periphery of the baffles 70 and the wall 13 of the body 2; the diameter outside the baffles 69 is adjusted to limit leakage by circulation between their periphery and the wall 13 of the body 2.

Claims (15)

1. A heat exchanger (1) for exchanging heat between at least two fluids, the heat exchanger comprising a body (2) defining a cylindrical cavity (3) of axis (4), a multiple tube bundle (5) extending inside the cavity and comprising a plurality of tubes (6) secured to two end tube plates (7, 8), the heat exchanger further comprising two caps (9, 10) fixed to the tube plates, together with two first sealing members (16, 17) provided at the respective peripheries of the two tube plates, and bearing radially against the cylindrical inside face (13) of the body (2) defining the cavity (3), which body (2) does not have a flange for fixing the caps and/or the bundle, the heat exchanger being characterized in that the body is essentially constituted by at least one section member segment extrusion-molded out of a non-ferrous metal alloy and in which the inside face (13) of the body (2) is not machined.
2. A heat exchanger according to claim 1, in which each of said two end tube plates (7, 8) includes a groove receiving said first sealing member constituted by an O-ring (16, 17).
3. A heat exchanger according to claim 1 or claim 2, in which the caps are molded out of plastics material.
4. A heat exchanger according to any one of claims 1 to 3, in which the body is made of quenched aluminum alloy.
5. A heat exchanger according to any one of claims 1 to 4, in which the bundle (5) further includes annular baffles (69) and disk-shaped baffles (70) which are disposed in alternation and are crimped onto the tubes (6).
6. A heat exchanger according to any one of claims 1 to 5, including two second sealing members (57, 58) provided respectively between each tube plate and the cap fixed thereto, said members being preferably being provided at the peripheries of the two tube plates and bearing radially against respective cylindrical end fittings (59, 60) of the caps (9, 10), and in which each end of the face (13) is extended by a chamfer (14, 15).
7. A heat exchanger according to any one of claims 1 to 6, in which the transverse profile of the outside face (21) of the body (2) is not entirely circular.
8. A heat exchanger according to claim 7, in which the wall (20) of the body (2) includes at least one longitudinal strip (24, 31, 33) projecting from the outside face (21) of the wall, and pierced by two orifices (18, 19) constituting inlet and outlet orifices for fluid into and from the cavity (3), and/or enabling the heat exchanger to be fixed to a support, and/or enabling connection couplings (36) to be fixed to fluid transport ducts.
9. A heat exchanger according to any one of claims 1 to 8, in which a cap (9, 10) is rigidly fixed to the central portion of a tube plate (7, 8) by removable rigid fastener means such as a screw via support means (65, 67) such as a bushing and/or an insert integrated in the cap, which screw extends inside the cap so as to be immersed in the fluid.
10. A heat exchanger according to claim 9, in which the cap includes at least two integrated thin connection elements (68) connecting the support means (65, 67) to the wall (62) of the cap.
11. A heat exchanger according to claim 10, in which said connection elements (68) extend radially, relative to the longitudinal axis (4) of the support means (65, 67), and in which the axis (4) passes through and/or extends in an extension of an opening for coupling the cap to a transport duct.
12. A heat exchanger according to any one of claims 1 to 11, in which the bundle of tubes further comprises at least one intermediate tube plate (40) having two annular grooves (41, 42) each receiving a sealing member (43) engaging the body.
13. A heat exchanger according to any one of claims 1 to 12, in which the body (2) comprises at least two portions (2a, 2b) in end-to-end alignment without being rigidly secured one to the other.
14. A heat exchanger according to any one of claims 1 to 13, in which a portion (23, 25) of the outside transverse profile of the body is dovetail-shaped, and in which the transverse profile of the inside face (13) of the wall (20) of the body is circular.
15. A method of manufacturing a heat exchanger according to any one of claims 1 to 14, in which a blank of the hollow body is made by extruding a non-ferrous metal to form a hollow section member that is cut up into segments, without machining the inside cylindrical portion and without machining the gasket-engaging surface.

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