DE10306848A1 - Flat tube with bend section forming heat exchanger for gas cooler or evaporator has bent over section with main bend axis parallel to flat tube plane and at definable angle to pipe length - Google Patents

Abstract

The flat tube (1) has a bent over section (3) so that connected sections (2a,2b) have opposite flow directions (4a, 4b) and mutually offset longitudinal axes (5a, 5b). The bent over section is formed so that a main bend axis (A) is parallel to the plane of the flat tube and at a definable angle to the pipe length, whereby the flat tube plane is defined by the length and width directions of the flat tube. An independent claim is also included for the following: (a) a gas cooler with an inventive device (b) and an evaporator with an inventive device.

Description

The invention relates to a Flat tube according to the preamble of claim 1 and to a constructed heat exchanger.

A generic flat tube with a reverse arc section and a heat exchanger with a built-up of this flat tube tube block are in the published patent application DE 198 30 863 A1 described. To produce the local flat tube with reverse arc section, the flat tube is bent in such a way that its two adjoining, planar tube sections extend in the longitudinal direction with opposite throughflow directions and with longitudinal axes offset at least in the transverse direction.

The publication EP 0 659 500 A1 also describes a flat tube with reverse arc section and a heat exchanger with a constructed from this flat tube type pipe block. To produce the flat tube there, a rectilinear flat-tube blank is first bent out of the flat tube plane in a U-shape until the flat-tube limbs run parallel to one another, after which the latter are twisted by 90 [deg.] Relative to the U-arc region. The resulting flat tube thus has two lying in a plane, plane pipe sections whose mouth ends lie on the same, the reverse arc section opposite side. The angle subtended by the flat tube transverse axis along the inverted arc portion with the plane in which the rectilinear tube legs lie increases from zero to the value of 90 ° present at the top end of the reverse arc portion over the one torsion region, and then over the other torsion region decrease again to 0 °. A disadvantage can be considered in the described reverse bend portion that the expansion of the flat tube perpendicular to the plane of the planar pipe legs in the head region of the Umkehrbogenabschnitts always corresponds to a flat tube width and therefore can not be reduced if necessary, so that the dimensions of the associated Wärmeübertragerrohrblocks in the direction perpendicular to Level of rectilinear flat tube legs can not be affected.

The object of the invention is a Flat tube with a Umkehrbogenabschnitt provide, which can be relatively easy to produce and to build a lot pressure stable heat exchanger with little space, as well as one of such flat tubes constructed heat exchanger specify.

This object is achieved with respect to the Flat tube with the features of claim 1 and with respect to a heat exchanger solved with the features of claims 13, 17 or 18.

The dependent claims relate to advantageous Training and developments of the invention.

The main idea of the invention exists in forming a reverse bend section such that a Main bending axis parallel to the flat tube level and below a predefinable Angle to Rohrlängserstrekkung runs, wherein the flat tube level by the length and width extension of the flat tube is determined. In an advantageous embodiment is the predeterminable angle 90 °, i.e. the main bending axis then runs perpendicular to the pipe extension.

The flat tube according to the invention is used during the forming parallel in the region of the reverse bend section in the flat tube plane moved to the tube extension by a path s, the path s itself from a flat tube width b and from a desired distance d between composed of the flat tube sections after the forming.

In the flat tube according to the invention is an angle α with in which the flat tube sections pass into the reverse curve section in the transformation of the flat tubes freely selectable and is in an advantageous embodiment of the invention in the range of 13 ° <α <67 °.

In an advantageous embodiment of the flat tube according to the invention the angle becomes α and / or the path s by at least one bending operation by at least one Bending axis (B) reaches, which is perpendicular to the flat tube plane.

In a particularly advantageous embodiment of the flat tubes according to the invention is the displacement of the flat tube by two bending operations by two Bending axes reached before or after the main bending process performed the first bending axis be, with the first bending axis in the middle of the offset range runs, where the offset range is approximately twice as long as the reverse arc section. This is especially true when a main bending operation is performed around a main bending axis, which is perpendicular to the pipe extension.

In the previously described flat tube according to the invention, the two planar tube sections adjoining the reverse curve section are arranged lying perpendicularly to the stacking direction z after the forming process in mutually laterally offset parallel planes, preferably with a spacing d in the transverse direction y between 0.2 mm and 20 mm. When using once umgestalt so bent flat tubes, if the direction of the offset is changed at each deflection, can form a serpentine tube block in which the serpentines extend laterally offset. The tube block thus formed has a depth of twice the flat tube width plus the said distance d between the planar tube sections. With bent flat tubes several times in the same direction, the tube block depth per reversal arc section increases by the flat tube width plus the said transverse distance d of the planar pipe sections. By the transverse distance form between the flat pipe sections corresponding column in a constructed with such flat tubes tube block, which facilitates the separation of condensation, for example in the application of the tube block in an evaporator of a motor vehicle air conditioning.

To achieve that the flat tubes lie in a common plane, is in a further transformation step the reverse bend section reshaped so that the two pipe sections next to each other and parallel with the distance d in a common Lie flat. This can be achieved by a symmetric or unbalanced Forming the reverse bow section done.

By switching between the Reverse arch sections in which the flat pipe sections in the same level - below referred to as first reverse arch sections - and the reverse arch sections, where the flat tubes lie in different levels - below referred to as second reverse arch sections -, can be a tube block in serpentine construction realize its depth of the number of consecutively formed first reverse arc sections. Through a constant change of first and second reverse arch sections in which the direction the offset is also carried out opposite, can be, for example, a Serpentine tube block with a depth of double Flat tube width plus realize the said distance d between the plane pipe sections, in which a temperature control, for example, a refrigerant or a coolant, first flows through the flat pipe sections, in a common Lie flat, and then flows through the flat pipe sections, the in the stacking direction or against the stacking direction in the next common plane lie.

But it is also possible to have one Serpentine design to achieve that a number of second Reverse arch sections are executed without lateral offset - below referred to as third reverse bend section -, for example in the stacking direction and then one first reverse bend portion is formed, which is a number from second reverse arc sections. Instead of the first reverse bend section of course also a second reverse bend section are arranged. At a such tube block are first all flat tube sections, one above the other lie in a front area, i. in an air facing Area, flows through the temperature control medium and then become after a first or a second turnaround section all in flows through a rear portion lying flat pipe sections "where the order of the flow also may be opposite, i. it will be the back area first and then flows through the front region, wherein the flow ever according to application from top to bottom or from bottom to top can be done.

In an alternative approach to Design of the inverted arch section, becomes the main bending process performed around the main bending axis at a predetermined angle to the pipe extension, wherein the predeterminable angle substantially corresponds to the angle α, with which the flat tube sections pass into the reverse curve section. After the main bending process are the two flat pipe sections in two mutually parallel planes, wherein the two flat tube sections a Include angles with a value of 2α. Around To obtain parallel pipe legs, the two pipe legs each with a further bending operation about a bending axis, the perpendicular to the flat tube plane, so reshaped that they each at the angle α in go over the reverse curve section. The procedure described provides in a different way the required already described offset of the flat tube.

The further transformation steps are analog performed to those already described to achieve that the two flat pipe sections next to each other and parallel with the Distance d lie in a common plane. This can, as already executed by a symmetrical or asymmetrical deformation of the reverse curve section respectively.

Basically, it is also possible the order to reverse the forming steps and by a symmetric or asymmetrical deformation of the reverse arc section, the two pipe sections first transform so that they lie in a common plane and enclose the angle of 2α and subsequently to perform the two bending operations described above to achieve that the two pipe sections parallel next to each other with the distance d in the common plane.

Overall, it is achieved by the inventive design of the reverse arc section that its extent in the stacking direction can be kept significantly smaller than the flat tube width. Accordingly, the spaces between adjacent flat tubes in the stacked structure of a tube block from these flat tubes need not be kept as large or not larger than the flat tube width, but can be much narrower, which favors the production of a compact and pressure-stable heat exchanger. In addition, the reverse bend section can be realized by relatively simple tube bending operations. The flat tube can be bent once or several times in this way, with its depth, ie its extension in the transverse direction as defined above, increases with each bend when the lateral offset always in the same Direction takes place. As a result, can be with arbitrarily narrow, pressure-stable flat tubes an arbitrarily deeper, ie forming in the transverse direction tube block, said transverse or depth direction usually represents that direction in which a medium to be cooled or heated passed outside the flat tube surfaces through the heat exchanger becomes. In this case, additional heat-conducting fins are usually provided between the stacked pipe block sections in order to improve the heat transfer. Since, as I said, the pipe interspaces can be kept very tight, also correspondingly low heat-conducting corrugated fins can be used, which also improves the compactness and stability of a tube-finned block thus formed.

For the production of a flat tube heat exchanger for motor vehicle air conditioners be several flat tubes according to the invention Stacked in stacking direction z to form a tube block. The flat tubes flow with one end in at least one laterally arranged in the stacking direction of Pipe block extending collection channel, wherein at least one of both, over the reverse bend portion interconnected pipe sections one in the stacking direction z wound pipe serpentine can form, and wherein the two flat tube ends on the same or on opposite Pages lie and at least one of the two pipe ends to one Angle between 0 ° and 90 ° twisted can be.

Due to the inventive design of the Flat tubes with a 180 ° deflection in the flow direction, Is it possible a smaller space for the heat exchanger such as a gas cooler or to realize an evaporator, because closer distances in the stacking direction and / or between the pipes can be realized. In addition, a spring-up the flat tube legs almost avoided. Another advantage lies in that the constructed with the flat tubes according to the invention Heat exchanger have a stiffer construction with tighter tolerances.

In the present gas cooler variant becomes the refrigerant in a flat tube in cross-countercurrent to the air out. At the opposite Blokkende takes a deflection by 180 °, d. H. the flat tube runs in the Same level as on the way back, but one way s offset laterally, so that the leading portion of the flat tube from the returning one Section is distanced by a distance d. The two flat pipe sections lie in the same plane, by the longitudinal and latitudinal extension the flat tubes is determined in their straight sections. The transformation is preferably carried out in three stages. In the first stage that experiences Flat tube from the extended state of a lateral offset. The amount of offset s corresponds to the sum of flat tube width b and distance d. Subsequently a bend is made with a radius r around a main bending axis A parallel to the flat tube plane and perpendicular to the tube extension, where r is the inner radius of the bend. The main bending axis A lies approximately in the middle of the offset area. The sections of the flat tube lie next parallel to each other in different levels. In a third step the Umkehrbogenabschnitt is reshaped so that the flat pipe sections again lie in a common plane. The transformed reverse arch section can be either completely below or above lie the common flat tube plane or symmetrical with respect to this common plane. In addition, any asymmetrical positions the reverse arc section to the common plane possible. alternative to the described Umformungsreihenfolge, the transformation steps also be reversed.

For the offset of the flat tube in the plane can be the following geometric Establish relationships: The angle α in which the flat tube in the offset area different from the original pipe extension extends is given by α = arctane (b + d / U). B: flat tube width, d: distance between the flat tubes, U: offset range.

For the offset range U, the following estimate results: U = 2 Π r, where r is the inner radius of the 180 ° arc. For the maximum inner radius r max: (h _r -d _FR ) / 2, where h _{r is} a fin height and d _{FR is} a flat tube thickness. A reasonable lower limit for r min is the flat tube thickness d _FR . According to these formulas, a meaningful value for α lies in the limits 13 ° <α <67 °. In an advantageous embodiment, the flat tube according to the invention forms a serpentine flat tube, by bending at least one of the two flat tube sections connected via an inverted arc section in the stacking direction to a tube serpentine; that is, it consists of successively in the stacking direction third Umkehrbogenabschnitten with the corresponding planar pipe sections. With flat tubes designed in this way, it is possible to build up a so-called serpentine heat exchanger with an arbitrary number of serpentine block parts which follow each other in the depth direction.

In a further embodiment of the flat tube according to the invention, the mouth ends lie on the same or on opposite sides, wherein at least one end, preferably both ends, are twisted in relation to the adjoining center region. By this twisting the flat tube transverse axis is rotated in the direction of the mouth end to the stacking direction, so that the extension of the flat tube ends in the transverse direction can be kept smaller than the flat tube width. At the maximum, the twisting takes place by 90 °, so that then, when the pipe sections are perpendicular to the stacking direction, the pipe ends are parallel to the stack tion and their extent in the transverse direction is only as large as the flat tube thickness. This enables a comparatively narrow arrangement of associated, in the depth direction of a pipe block constructed therewith, collecting and distribution channels extending in the stacking direction on the relevant pipe block side.

A heat exchanger is by use one or more of the flat tubes according to the invention in the construction of a corresponding tube block characterized with the above-mentioned properties and advantages of such a tube block construction. In particular, can be in this way, a compact, highly pressure-stable evaporator with relatively low weight, low internal volume and good condensate separation for one Realize air conditioning of a motor vehicle, preferably Multi-chamber flat tubes are used. The heat exchanger is both in single-layer construction, in which the flat pipe sections between two Umkehrbogenabschnitten or between an inverted arc section and a flat tube end consist of a plan, straight pipe section, as well Serpentine construction, in which these flat pipe sections bent into a coil are.

For a trained heat exchanger are the tube ends of the flat tubes used and thus also the associated ones Collection and distribution channels, hereafter referred to as collection channels for the sake of simplicity, on opposite Tube block sides. The collection channels can then be formed by a respective collection box or manifold, the at the relevant pipe block side along the stacking direction, too run as Blockhochrichtung run and the parallel feed or removal of the tempering medium conducted through the interior of the pipe to or serve from the individual flat tubes.

In an alternative training of the invention the flat tube ends all on the same tube block side. Due to the design of the flat tubes are the two pipe ends of each flat tube to each other offset in the block depth direction, so that they two in accordance with Block depth direction associated with adjacent collecting channels can be. Accordingly, supply and discharge of the through the tube interior guided tempering on the same heat exchanger side.

In a further embodiment of this Wärmeübertragertyps with two adjacent collection channels on the same tube block side is provided, these collection channels by two separate headers, followed by simplicity half uniformly referred to as headers, or by a common To form manifold. The latter can be realized by the existence first uniform collection tube interior with a longitudinal partition divided into the two collection channels is, or by the fact that the manifold as an extruded tube profile with two separate, forming the collection channels Hollow chambers is made.

For a trained heat exchanger is at least one of the two manifolds or at least one the two hollow chambers of a longitudinally divided Collecting pipe by transverse partitions in several subdivided in block vertical direction collecting channels. As a result, a group-wise serial flow through the flat tubes in the tube block achieved by the pipe block via a first collecting channel the transversely divided manifold or the transverse split chamber supplied temperature control first only in the opening there Part of all flat tubes is fed. The collecting channel in the this part of the flat tubes opens with the other end of the tube, then acts as a deflection channel, in which the tempering of the there emanating Flat tubes in another, also there opens out with one end Part of all flat tubes is deflected. Determine the number and position of the transverse partitions the division of the flat tubes in successively flowed through groups flowed through in parallel Flat tubes.

In a flat tube produced according to the invention the arrangement of the flat tubes with respect to an air flow remains despite the reverse curve section unchanged, d. H. an air-facing side of the flat tube is also after the reverse arc section continues to face the air and one of Air side facing away from the flat tube is also after the reverse arc section still averted from the air.

In contrast, a situation becomes the Rohrunter- or Rohroberseite by the reverse bend section changed d. H. the tube underside of the flat tube becomes the tube top of the Flat tube and a Rohroberseite the flat tube is the tube bottom of the flat tube.

Advantageous embodiments of the invention are shown in the drawings and will be described below. Hereby show:

1 a plan view of a flat tube with a Umkehrbogenabschnitt and twisted pipe ends;

2a Side view along the arrow I in 1 a flat tube having a second reverse arc portion;

2 B to 2d Side views along the arrow I of 1 of flat tubes with differently executed first Umkehrbogenabschnitten;

3a a plan view of a flat tube before a bending operation about a main bending axis A;

3b a plan view of a flat tube after a bending operation about a main bending axis A;

4 a partial side view of a flat tubes according to the 1 and 2 constructed tube / rib block of a heat transfer gers,

5 1 is a partial side view of a tube / rib block of a heat exchanger with serpentine flat tubes,

This in 1 Flat tube shown in a plan view 1 is manufactured in one piece from a linear multi-chamber profile using suitable bending processes. It includes two flat, straight tube sections 2a . 2 B , which have a reverse curve section 3 are interconnected and opposite flow directions for one through the plurality of parallel chambers in the interior of the flat tube 1 passed tempering medium, for example, a refrigerant of a motor vehicle air conditioner, have. One of the two possible flows is in 1 through appropriate flow arrows 4a . 4b shown. The parallel to the flow directions 4a . 4b extending longitudinal axes 5a . 5b the two plan, straight pipe sections 2a . 2 B define a longitudinal direction x and are offset from one another in a transverse direction y perpendicular thereto. As in particular from the side views of 2 B to 2c it can be seen, are the two plan pipe sections 2a . 2 B with a first turnaround section 3 in a common xy-plane, which is perpendicular to a stacking direction z, in which a plurality of such flat tubes are stacked to form a heat exchanger tube block, as described below with reference to 4 , and 5 is explained in more detail. For better orientation are in the 1 to 5 in each case the corresponding coordinate axes x, y, z drawn.

The reverse arch section 3 is obtained in that the initial, straight flat tube profile of a desired width b in the region of an offset region U as in 3a shown in the flat tube plane parallel to the tube extension is displaced by a distance s, which is composed of the tube width b and the desired distance d. The shift or the offset can take place in the positive y-direction or in the opposite direction in the negative y-direction. The transition between the flat pipe sections 2a . 2 B and the turnaround section 3 occurs at a predetermined angle α. The angle α and / or the path s are achieved by at least one bending operation about at least one bending axis B1, B2, which runs perpendicular to the flat tube plane. Preferably, the described offset by the path s by two bending operations around the in 3a achieved bending axes B1 and B2, wherein these two bending operations are preferably performed before the bending process about the main bending axis A. The main bending axis A runs in the illustrated embodiment in the middle of the offset region U, wherein the offset region U is approximately twice as long as the reverse arc section 3 ,

In the manner described one obtains the two rectilinear pipe sections 2a . 2 B of the flat tube 1 , After the offset of the flat tube 1 and the main bending process are the two rectilinear pipe sections 2a . 2 B as in 2a represented offset in mutually parallel planes with a selectable distance 2r in the z-direction and in the selectable distance d in the y-direction, with the following for the maximum inner radius r: (h _r -d _FR ) / 2, where h _{r is} the fin height and d _{FR is} the flat tube thickness, this makes more sense lower limit for r the flat tube thickness d _FR . According to these formulas, a reasonable value for the angle α lies in the limits 13 ° <α <67 °. The selectable distance is preferably between about 0.2 mm and 20 mm, while the flat tube width b is typically between one and a few centimeters.

While the straight pipe sections 2a . 2 B on one side over the reverse curve section 3 connected to each other, they both run on the opposite side in the form of twisted pipe ends 6a . 6b out. The twisting takes place around the respective longitudinal central axis 5a . 5b , Alternatively, to a longitudinal axis parallel thereto, ie with a transverse offset with respect to the longitudinal center axis, by any angle between 0 ° and 90 °, in the case shown, the torsion angle is about 90 °.

Out 2 It is clear that due to the described formation of the Umkehrbogenabschnitts 3 the height c of the turnaround section 3 and thus the expansion in the stacking direction z is small and can be selected depending on the bending radius. In particular, this height c of the reverse curve section remains 3 significantly smaller than the flat tube width b. As a result, a plurality of such flat tubes can be stacked in a heat exchanger tube block with a stack height, which can be kept significantly smaller than the flat tube width, as the heat exchanger examples described below show. Another modification of the flat tube of the 1 and 2 may be that the two plan pipe sections 2a . 2 B as in 2a shown in two staggered xy planes lie. In this case, the transverse direction y is defined by being perpendicular to both the longitudinal direction x of the rectilinear pipe sections and the pipe block stacking direction z.

The 3b shows an alternative way to design the reverse curve section 3 after a main bending process. How out 3b It can be seen here is only the main bending process performed around the bending axis A, before the offset is realized by further bending operations about a bending axis B3. The main bending axis A extends at the predeterminable angle α in the limits of 13 ° <α <67 ° to the tube longitudinal extension. After the main bending process, the two pipe sections are each around the bending axis 3 bent inwards according to the arrows. As shown in 3b the distance d between the flat tubes is realized by a limitation, in the example shown realized by a boundary strip with the width d, in the illustrated example, the bending axis B3 is realized by an upper end of the boundary strip. The illustrated flat pipe sections 2a and 2 B lie in different parallel planes and close a diaper of 2a on. After the additional bending operations are the two flat pipe sections 2a and 2 B parallel to each other in the different parallel planes, as in 2a represented, so that the other already described forming steps can be performed in order to achieve that the two flat pipe sections 2a . 2 B lie parallel with the distance d in a common plane (see 2 B to 2c ).

The 4 and 5 show an application for the flat tube type of 1 and 2 in the form of a tube / rib block 9 an evaporator 10 as it is particularly useful in automotive air conditioning systems. It is understood that the heat exchanger shown in some sections can also be used for any other heat transfer purposes, for example as a gas cooler, depending on the design. How out 4 As can be seen, this evaporator includes 10 between two end cover plates 11 . 12 a stack of several flat tubes 1 according to 1 and 2 with intermediate, thermally conductive corrugated ribs 8th , The height of the heat-conducting ribs 8th corresponds approximately to the height c of the flat tube reverse arc sections 3 and is thus significantly smaller than the flat tube width b.

By using the flat tube 1 of the 1 and 2 becomes a tube-rib block 9 formed in the depth, ie in the y-direction, two-part structure, wherein in each of the two block parts in each case the pipe sections with the same flow direction in the stacking direction z are superimposed. Between the two block parts is the distance d of the two straight pipe sections 2a . 2 B each flat tube 1 corresponding gap formed. The corrugated ribs 8th extend in the illustrated embodiment in one piece over the entire flat tube depth and thus across this gap away, where they can survive on both sides, ie at the front and at the back of the block, as needed. But it is also possible multi-part, in particular two-piece corrugated fins 8th to use. The block front side is in this case defined by the fact that it is in the tube transverse direction y, ie in the block depth direction, by a second tempering, for example to be cooled supply air for a vehicle interior on the outside over the evaporator surfaces, flows.

The transverse extent of the flat tube mouth ends is smaller than the flat tube width b due to their twisting. This facilitates the connection of two associated, in the 4 not shown collecting ducts, each of which may be formed by a collection box or manifold whose transverse extension in the y direction does not need to be greater than the flat tube width b and in its diameter at a torsion angle of the flat tube ends of about 90 ° even only slightly larger than the flat tube thickness needs to be. It is therefore easily possible to arrange two manifolds on the relevant side of the tube block side by side in the stacking direction z running, in each case one of the two ends of each flat tube 1 take. Alternatively, a common manifold for both stack rows of pipe ends 6a . 6b be provided, which is divided by means of a longitudinal partition in the two required, separate collection channels.

It turns out that the evaporator 10 with the tube / rib block thus formed 9 in a compact design and very pressure stable can be realized while having a high heat transfer efficiency. By bending the flat tubes to two offset in the block depth pipe sections 2a . 2 B can be achieved with relatively narrow flat tubes, a heat transfer performance for the otherwise at least about twice as wide, not curved flat tubes would be required. At the same time is achieved by the one-time Flachrohrumlenkung that the passing through the inside of the tube temperature control on one and the same side of the tube block can be supplied and removed, which is advantageous in some applications.

In the 5 an embodiment is shown in serpentine construction. The cutaway view of 5 shows several serpentine flat tubes 13 , which are stacked to form the local serpentine tube block in any desired number of stacked. The serpentine flat tube used for this purpose 13 is largely identical to the one of 1 and 2 with the exception that on both sides of that of the 1 and 2 similar reverse arc section 3 each not only a straight, single-layer pipe section, but a multiple serpentine wound coil section 12 connects, which in turn are offset in block depth direction by a corresponding gap. The serpentine turns 12 of the respective coil section 13 are formed as usual by bending the flat tube at the relevant point to the local pipe transverse axis by an angle of 180 °. Between the individual pipe coil turns 13 as well as between successive serpentine flat tubes 12 are thermally conductive corrugated ribs 8th continuously introduced from the block front side to the back of the block with optional projection. It is understood that here as well as in the example of 4 and 5 instead, one row of corrugated fins may be provided for each of the two rows of tube blocks offset in the direction of the block depth, in which case the gap between the two block rows may also remain free. Instead of this half pitch with two equal width corrugated fins, of course, any other over the tube block depth in each corrugated fin layer Number of corrugated fins and / or corrugated fins are used with different widths, for example, a first, over two-thirds of the tube block depth extending and a second, extending over the remaining third of the tube block depth corrugation. In any case, the gap promotes the condensation of the evaporator.

Like from the 4 and 5 to recognize corresponds in this example, the height of the heat-conducting ribs 8th and thus the stack spacing of adjacent, straight flat tube sections both within a serpentine flat tube 13 as well as between two adjacent serpentine flat tubes 13 in about the opposite to the flat tube width b significantly lower height c of the Umkehrbogenabschnitts 3 ' , The selected in this case twisting of the turn opening on the same side of the block flat tube ends 6 of 90 ° does not collide with this low stack height, since the serpentine flat tubes 13 due to their coil snake sections 12 in total, each have a height greater than the flat tube width in the stacking direction z. The orthogonal twisting of the ends 6 by 90 ° allows, as mentioned, the use of particularly narrow collecting ducts or these forming headers. In 5 is such a front header 7 represented, in which the front row of the flat tube ends 6 opens. In addition, as in 5 illustrated the serpentine flat tubes 13 with the flat tube 1 of the 1 and 2 be combined.

To the two shown flat tube designs Many other alternatives are possible. So can the flat tube have two or more reverse bow sections and corresponding deflections.

In addition, the serpentine flat tube 13 from 5 be modified to the effect that at least one more serpentine turn in one and / or in the other serpentine tube section, the respective flat tube end 6 on the reverse curve section 3 opposite block side comes to rest. In another embodiment, a serpentine flat tube 13 the kind of 5 but with one or more additional reverse bend sections 3 be provided so as to build a block in the depth direction at least three-part tube block for a serpentine heat exchanger. Depending on the application, the flat tube ends 6 also be left untrained.

In those embodiments in which the flat tube ends 6 on the same block side can, instead of two manifolds 7 or a common manifold into which a longitudinal partition is separately introduced in the manufacture, a two-chamber manifold can be used which already has two separate, longitudinal hollow chambers in the production stage. It is made of an extruded profile and integrally includes two separate longitudinal chambers, which form the collecting channels for the relevant heat exchanger. For this purpose, as in the other manifold versions, suitable circumferential slots in the manifold 7 bring in, in which the flat tube ends 6 be tightly inserted.

Depending on the heat exchanger type can also manifolds be used, which by means of corresponding transverse walls several, in the block uprising z include separate collection channels. As a result, the flat tubes in the tube block to several groups such summarized, that the Pipes of one group in parallel and the different pipe groups in series flows through become. A fed Temperature control medium flows from an inlet-side collection channel in the group of there opening Flat tubes and then passes at the other end in a deflection space acting collecting channel, in addition to this first group a second flat tube group opens, in which the temperature control medium is then deflected. This can be done by appropriate positioning of the transverse walls in one or both headers continued in any way up to an exit-side collection channel be over the tempering then leaves the tube block.

The above description of various embodiments shows that yourself with the flat tubes according to the invention very compact, pressure stable flat tube blocks in single layer construction or serpentine construction with high heat transfer capacity to let. With it produced heat exchanger are suitable e.g. also for relatively high pressure CO2 air conditioning systems, such as she increasingly for Motor vehicles to be considered.

Claims (18)

Flat tube with an inverted arc section ( 3 ), in which the flat tube ( 1 ) is bent over in such a way that its two adjoining, planar pipe sections ( 2a . 2 B ) in the longitudinal direction with opposite flow directions ( 4a . 4b ) and with at least in the transverse direction (y) offset longitudinal axes ( 5a . 5b ), characterized in that the reverse bend section ( 3 ) is formed such that a main bending axis (A) extends parallel to the flat tube plane and at a predeterminable angle to the tube longitudinal extension, wherein the flat tube plane through the length and width extent of the flat tube ( 1 ) is determined. Flat tube according to claim 1, further characterized that the predetermined angle is 90 °. Flat tube according to claim 1 or 2, further characterized in that the flat tube ( 1 ) in the area of the reverse curve section ( 3 ) in the flat Tube level is parallel to the pipe extension by a distance (s) is shifted. Flat tube according to one of claims 1 to 3, characterized in that the pipe sections ( 2a . 2 B ) at a predeterminable angle (α) in the reverse bend section ( 3 ) pass over. Flat tube according to one of claims 3 or 4, characterized that the angle (α) and / or the path (s) by at least one bending operation by at least one Bending axis (B) is reached, which is perpendicular to the flat tube plane. Flat tube according to claim 5, further characterized in that the displacement of the flat tube ( 1 ) is achieved by two bending operations around two bending axes (B1, B2), which are performed before or after the main bending operation about the first bending axis (A), wherein the first bending axis (A) extends in the middle of an offset region (U). Flat tube according to one of the preceding claims, further characterized in that the two, at the reverse arc section ( 3 ), plan pipe sections ( 2a . 2 B ) in mutually parallel planes perpendicular to the stacking direction (z) lying at a distance (d) are arranged, Flat tube according to one of the preceding claims, further characterized in that in a further reshaping step the reverse arc section (FIG. 3 ) is formed so that the two pipe legs ( 2a . 2 B ) lie side by side and parallel with the distance (d) in a same plane. Flat tube according to claim 7, further characterized in that the reverse bend portion ( 3 ) is deformed symmetrically or asymmetrically. Flat tube according to one of claims 7 or 8, characterized that the distance (d) in the transverse direction (y) between 0.2 mm and 20 mm is. Flat tube according to one of the preceding claims, characterized in that by the reverse arc section ( 3 ) an air-facing side of the flat pipe section ( 2a ) to an air facing side of the flat pipe section ( 2 B ) and a side facing away from the air of the flat pipe section ( 2a ) to a side facing away from the air of the flat pipe section ( 2 B ) becomes. Flat tube according to one of the preceding claims, characterized in that by the reverse arc section ( 3 ) a pipe underside of the pipe section ( 2a ) to the pipe top side of the pipe section ( 2 B ) and a Rohroberseite the pipe section ( 2a ) to the pipe bottom of the pipe section ( 2 B ) becomes. Flat tube heat exchanger for a motor vehicle air conditioning system, with - a tube block ( 9 ) with one or more in a stacking direction (z) stacked flat tubes ( 1 ) according to one of claims 1 to 11. Flat tube heat exchanger according to claim 13, characterized in that the side of the tube block ( 9 ) along the stacking direction (z) extending collecting channels ( 7 ) are arranged, in which the flat tubes ( 1 ) with one end each ( 6 ). Flat tube heat exchanger according to claim 13 or 14, characterized in that at least one of the two, over the reverse arc section ( 3 ) interconnected pipe sections ( 2a . 2 B ) a wound in the stacking direction (z) pipe serpentine ( 12 ). Flat tube heat exchanger according to one of claims 13 to 15, characterized in that the two flat tube ends ( 6 ) lie on the same or on opposite sides and at least one of the two pipe ends ( 6a . 6b ) is twisted by an angle between 0 ° and 90 °. Gas cooler with a flat tube heat exchanger ( 10 ) according to any one of claims 13 to 16. Evaporator with a flat tube heat exchanger ( 10 ) according to any one of claims 13 to 16.