EP0391781B1 - Double tubes for mixed boiler, methode of production and corresponding boilers - Google Patents

Abstract

Double tube for a mixed boiler, comprising rectilinear segments in which the two sections of pipe are juxtaposed laterally. Each section (A, B) is delimited on the side furthest from the other section by a sheet (1, 7), the two longitudinal edges (2, 3, 8, 9) of which are curved and are welded against the longitudinal edges of an intermediate partition (4) and this intermediate partition has shaped bosses (5), the tops (6) of which are in contact with and joined to said sheets. <IMAGE>

Description

The invention relates to mixed hot water boilers, that is to say boilers intended to heat water to supply both a central heating circuit and a sanitary or hot water drawing circuit.

It relates more particularly, among these boilers, those whose heat exchanger is equipped with double pipes, that is to say comprising two metal pipes assigned respectively to the two independent water circuits, these pipes comprising rectilinear segments in which the two conduits are juxtaposed laterally, segments generally braced by parallel cooling fins brazed to them, and curved segments, generally in a semicircle connecting together the rectilinear segments and forming with them a serpentine.

The invention also relates to the double pipes of said boilers and more particularly their rectilinear segments.

In the known embodiments (see for example the patent FR-A-1 332 607) and CH-A-398 657 the rectilinear segments of the kind in question consist of two metal tubes welded laterally one against the other.

• - il est difficile de prévoir à l'intérieur de chaque tube des entretoises rigides reliant la paroi, de ce tube, qui est accolée à l'autre tube, à la paroi opposée, entretoises aptes à empêcher les déformations du tube lors du fonctionnement de la chaudière par suite des dilatations thermiques et/ou des poussées hydrauliques dues à la circulation de l'eau,
• - la paroi double qui se trouve au milieu de la tubulure correspond à un excédent de métal inutile,
• - il est difficile d'assurer un bon soudage mutuel des deux composants de ladite paroi double.

This formula has a number of drawbacks and in particular the following:

• - It is difficult to provide inside each tube rigid spacers connecting the wall, of this tube, which is attached to the other tube, to the opposite wall, spacers capable of preventing deformation of the tube during the operation of the boiler as a result of thermal expansion and / or hydraulic thrusts due to the circulation of water,
• - the double wall which is in the middle of the tubing corresponds to an unnecessary excess of metal,
• - It is difficult to ensure good mutual welding of the two components of said double wall.

The invention aims, among other things, to remedy these drawbacks.

To this end, the rectilinear segments of the double pipes of the kind in question according to the invention, comprising two sections of metal pipe juxtaposed laterally, are essentially characterized in that at least one of these two sections is delimited, on its most distant from the other section, by a metal strip whose two longitudinal edges are curved and are welded against the longitudinal edges of an intermediate metal partition also forming part of the segment considered and in that this intermediate partition has stamped bosses whose vertices are in contact with the blade and are secured to it.

• - les deux tronçons sont délimités extérieurement par des lames symétriques l'une de l'autre par rapport au plan moyen de la cloison intermédiaire, alors plane,
• - dans un segment rectiligne selon l'alinéa précédent, chaque extrémité longitudinale de la cloison intermédiaire est déformée transversalement en S de façon à présenter deux demi-godets longitudinaux ouverts vers l'extérieur, séparés l'un de l'autre par un pontet non déformé de la cloison, et dont les fonds sont juxtaposés jointivement contre les lames en regard, et chaque extrémité longitudinale de lame est elle-même déformée en son milieu par un demi-godet longitudinal ouvert vers l'extérieur dont le fond est juxtaposé jointivement contre le pontet de la cloison intermédiaire, ce qui délimite deux cols dont les sections sont de préférence différentes, ces cols étant raccordés à des tronçons de tuyauterie extérieurs indépendants,
• - les bords recourbés des lames sont orientés perpendiculairement aux bords de la cloison intermédiaire sur lesquels ils sont soudés et les tranches terminales des premiers bords sont juxtaposées contre les faces latérales des seconds bords,
• - les bossages faisant saillie respectivement sur les deux faces de la cloison intermédiaire sont prévus de façon telle que les perturbations qu'ils créent sur les courants d'eau circulant dans les deux tronçons de conduite constitutifs du même segment rectiligne comprenant cette cloison soient différentes,
• - dans un segment rectiligne selon l'alinéa précédent, les bossages faisant saillie respectivement sur les deux faces de la cloison intermédiaire sont tous identiques, mais leurs nombres sont différents,
• - la cloison intermédiaire est constituée par une feuille plus épaisse que les feuilles constitutives des deux lames à bords recourbés rapportées par soudure sur cette cloison.

In certain embodiments, use is also made of one and / or the other of the following provisions:

• the two sections are delimited externally by blades which are symmetrical to one another with respect to the mean plane of the intermediate partition, then plane,
• - In a rectilinear segment according to the preceding paragraph, each longitudinal end of the intermediate partition is deformed transversely in S so as to present two longitudinal half-buckets open towards the outside, separated from each other by a non-trigger guard deformed of the partition, and the bottoms of which are juxtaposed contiguously against the facing blades, and each longitudinal end of the blade is itself deformed in its middle by a longitudinal half-bucket open towards the outside, the bottom of which is juxtaposed contiguously against the trigger guard of the intermediate partition, which delimits two necks whose sections are preferably different, these necks being connected to independent external pipe sections,
• the curved edges of the blades are oriented perpendicular to the edges of the intermediate partition on which they are welded and the end sections of the first edges are juxtaposed against the lateral faces of the second edges,
• the bosses projecting respectively on the two faces of the intermediate partition are provided in such a way that the disturbances they create on the water currents flowing in the two pipe sections constituting the same rectilinear segment comprising this partition are different,
• - in a rectilinear segment according to the preceding paragraph, the bosses protruding respectively on the two faces of the intermediate partition are all identical, but their numbers are different,
• - The intermediate partition is constituted by a thicker sheet than the constituent sheets of the two blades with curved edges reported by welding on this partition.

The invention also relates to heat exchangers comprising pipes as defined above as well as boilers equipped with such exchangers.

It also relates to the methods for manufacturing such pipes, said methods being essentially characterized in that, during the juxtaposition of the elements to be welded against each other, there is slightly overflowed in each zone to be welded an edge of a such an element so that the excess edge constitutes filler metal during welding, which is obtained by scrolling said zone opposite a welding head.

The invention comprises, apart from these arrangements high to melt said material at the vertices 6.

As can be seen in the drawing, each rectilinear segment composed of two adjoining sections A and B is ultimately delimited by two parallel flat portions connected to each other by two curved portions of semi-circular section: the cross section of this segment is basically writable in an elongated rectangle whose width is generally between 40 and 100 mm, being generally of the order of 60 mm.

The bosses 5, for their part, are advantageously in the form of rounded nipples whose base is oval and elongated in the longitudinal direction of the tuber, the major axis of the oval being of the order of 8 mm and its small axis, of the order of 4 mm and the longitudinal gap reserved between the successive bosses being of the order of 8 mm.

To allow easy mutual connection of the rectilinear segments U defined above with the aid of the intermediate curved degents V, the longitudinal ends of these rectilinear segments are advantageously arranged in the following manner (see FIGS. 3 and 4).

Each longitudinal end of the intermediate partition 4 is deformed transversely along an S so as to reveal two longitudinal half-cups 11, 12 open longitudinally towards the outside and projecting respectively on the two opposite faces of the partition.

These two half-buckets are separated from each other by a bridge 13 not deformed from said partition.

The depth of each half-bucket is equal to the thickness of a section (A, B) so that its bottom is juxtaposed contiguously against the blade (1, 7) opposite. Each dem-bucket 11, 12 is separated from the adjacent longitudinal edge of the partition 4 by a flat, non-deformed narrow margin (15, 16) of this partition.

In addition, the central region of each longitudinal end of the blade is deformed so as to reveal there a longitudinal half-bucket 14 smaller than the previous ones, also open longitudinally towards the outside and the depth of which is such that its bottom is juxtaposed. joined against the trigger guard 13.

The portions of walls in mutual contact are advantageously shuffled against one another.

Under these conditions, two cylindrical terminal necks 17, 18 are formed at each longitudinal end of each straight segment U, necks each serving only one of the two sections A and B of this segment.

Thus the neck 17 serving the only section A (fig. 3 and 4) is delimited by the half-bucket 11 and the facing portion of the blade 1, this neck being closed, on the side of the longitudinal edge of the segment considered, by welding the curved edge 2 against the margin 15, and on the middle side of the height of said segment, by applying the bottom of the corresponding half-bucket 14 against the trigger guard 13.

• - de préparer les pièces 1, 4 et 7 par un emboutissage de bandes métalliques rectangulaires faisant apparaître dans ces bandes les différentes aspérités ci-dessus décrites (bossages 5 et demi-godets 11, 12 et 14),
• - de juxtaposer ces trois pièces avec interposition éventuelle d'un matériau de brasage,
• - de les réunir par les cordons de soudure 10 ci-dessus décrits,
• - et de chauffer le tout jusqu'à obte,tion d'une liaison intime entre les différentes surfaces juxtaposées jointivement.

The manufacture of the collars 17 and 18 follows automatically from the manufacture of the rectilinear segment of corresponding tubing, which is extremely simple since it suffices:

• - to prepare the parts 1, 4 and 7 by stamping rectangular metal strips showing in these strips the different roughness described above (bosses 5 and half-cups 11, 12 and 14),
• - to juxtapose these three parts with possible interposition of a brazing material,
• - to join them by the weld beads 10 described above,
• - and to heat everything until an intimate connection is created between the different surfaces juxtaposed contiguously.

It is then easy to connect in pairs the cylindrical necks 17, 18 of the successive rectilinear segments U using the segments V curved in a semicircle and having profiles complementary to those of said necks, the ends of these curved segments being fitted joined in said passes as well as visible on fugure 5.

In the embodiments which have been illustrated in FIGS. 2 and 3, the numbers of the bosses 5 projecting respectively from the two faces of the partition 4 are identical so that the turbulence imposed on the water currents flowing respectively in the two sections A and B is the same.

According to a variant which may be advantageous in certain cases and which has been shown diagrammatically in FIG. 6, the numbers of these bosses projecting respectively on either side of the partition 4 are given different values, this number being higher for the section A in which the heating water circulates as in the section B in which the drawing water circulates.

The Applicant has in fact observed that the risk of scaling is higher than in the second circuit than in the first since, in the first case, the heating water circulates in a closed circuit and therefore carries a proportion of charges mineral weaker and weaker as it circulates.

As the degree of scaling of a pipe is as much higher as the water circulating in this trubulence is itself all the higher as the number of bosses protruding in the pipe considered is itself higher, we it would be beneficial to give this number a higher value here in the heating section A than in the drawing section B.

In the example illustrated in Figure 6, the number

of these bosses projecting in the section A, bosses represented in spectrum, is equal to twice the number of the bosses projecting in the section B and shown in solid line.

The pressure drops having more disadvantages in the heating circuit - which generally includes a circulator - than in the drawing circuit, it is advantageous to reduce these pressure drops in the first circuit as much as possible.

To this end, according to a preferred embodiment, the necks 17 above assigned to the heating circuit are given a larger section than that of the necks 18 assigned to the drawing-off circuit.

Following which, and whatever the embodiment adopted, there are finally tubes and heat exchangers whose constitution results sufficiently from the above.

• - les tubulures considérées sont indéformables du fait de la présence des bossages d'entretoisement dans celles-ci,
• - les échanges thermiques entre les deux conduites sont excellents, vu en particulier la conductibilité thermique assurée par les bossages eux-mêmes,
• - la formule proposée permet une économie de métal par rapport à celles faisant appel à des tubes rapportés l'un contre l'autre et conduisant à la formation de parois doubles,
• - la fabrication est très simple puisque les opérations d'emboutissage et de juxtaposition sont elles-mêmes très simples et que les opérations de soudure sont ici faciles à exécuter et localisées selon des cordons de faible épaisseur.

These pipes and exchangers have many advantages over those previously known, and in particular the following:

• - the pipes considered are non-deformable due to the presence of the bracing bosses therein,
• - the heat exchanges between the two pipes are excellent, in particular given the thermal conductivity provided by the bosses themselves,
• - the proposed formula allows a saving of metal compared to those using tubes added against each other and leading to the formation of double walls,
• - The manufacturing is very simple since the stamping and juxtaposition operations are themselves very simple and that the welding operations are here easy to execute and localized according to thin cords.

As is obvious, and as already follows from the foregoing, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all its variants.

Claims (10)

1. Double pipe rectilinear segment for mixed boilers comprising two laterally juxtaposed metal duct sections (A,B), characterized in that one at least of these two sections (A) is defined, on its side the furth- est away from the other section (B), by a metal plate (1) whose two longitudinal borders (2,3) are curved and are welded against the longitudinal borders of an intermediate metal partition (4) also forming part of the segment considered and in that this intermediate partition has stamped bosses (5) whose tops (6) are in contact with the plate and are fixed thereto.

2. Pipe segment according to claim 1, characterized in that the two sections (A,B) are defined outwardly by plates (1,7) which are symmetrical with each other with respect to the mean plane of the intermediate partition (4), then flat.

3. Pipe segment according to any one of the pre- ceding claims, characterized in that the curved borders (2,3,8,9) of the plates (1,7) are oriented perpendicularly to the borders ofthe intermediate partition (4) to which they are welded and in that the end edges of the first borders are juxtaposed against the lateral faces of the second borders.

4. Pipe segment according to any one of the preceding cliams, characterized in that the bosses (5) projecting respectively from the two faces of the intermediate partition (4) are formed so that the disturbances which they create in the water streams flowing through the two duct sections (A,B) forming the segment are different.

5. Pipe segment according to claim 4, characterized in that the bosses (5) projecting respectively from the two faces of the intermediate partition (4) are all identical, but their numbers are different.

6. Pipe segment according to any one of the preceding claims, characterized in that the intermediate partition is formed by a sheet thicker than the sheets forming the two plates (1,7) with curved borders welded to this partition.

7. Pipe segment according to at least claim 2, characterized in that each longitudinal end of the intermediate partition (4) is deformed transversely in the form of an S so as to have two longitudinal halfcups (11,12) open outwardly, separated from each other by a non deformed bridge (13) of the partition and the bottoms of which are juxtaposed jointingly against the facing plates (1,7), and in that each longitudinal plate end (1,7) is itself deformed in the middle by a longitudinal outwardly open half-cup (14) whose bottom is juxtaposed jointingly against the bridge (13) of the intermediate partition (4), what defines two necks (17,18).

8. Pipe segment according to claim 7, characterized in that one of the necks (17) has a larger section than the other (18).

9. Double pipe for mixed boilers, characterized in that it is formed of rectilinear segments (U) according to any one of claims 7 and 8 connected together by curved tubular segments (V), particularly in the form of a semi-circle, fitted jointingly in the necks (17,18) of said rectilinear segments.

10.Method for manufacturing a rectilinear pipe segment according to any one of claims 1 to 7, characterized in that, when the elements to be welded (1,4,7) are juxtaposed one against the other, the border of one of such elements is caused to project slightly in each zone to be welded so that the projecting border (T) forms a filler metal for welding, what is obtained by causing said zone to travel past a welding head (S).

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