WO2005066566A1

WO2005066566A1 - Heat exchanger

Info

Publication number: WO2005066566A1
Application number: PCT/EP2004/013832
Authority: WO
Inventors: Wolfgang Kramer
Original assignee: Behr Gmbh & Co. Kg
Priority date: 2004-01-07
Filing date: 2004-12-06
Publication date: 2005-07-21
Also published as: DE102004001306A1; EP1706698A1; US20080190589A1

Abstract

The invention relates to a heat exchanger and a rib (1), in particular a corrugated rib (1), especially for a flat tube heat exchanger, in particular a coolant or charge-air cooler for motor vehicles. The corrugated rib (1) is arranged between flat tubes (3) of the heat exchanger, is connected thereto in a material fit, comprises gills (6, 8), can be exposed to a flow of air and comprises moulded reinforcement means.

Description

BEHR GmbH & Co. KG Mauserstrasse 3, 70469 Stuttgart

Heat exchanger

The invention relates to a heat exchanger, such as, in particular, a flat tube heat exchanger, and a fin, such as, in particular, a corrugated fin, for example for a flat tube heat exchanger, in particular for a coolant, charge air cooler or condensers or evaporators for motor vehicles according to the preamble of patent claim 1.

Such heat exchangers are known from the applicant's EP 0 547 309 Bf.

Corrugated fins and flat tubes form a soldered cooling system in which a medium to be cooled, e.g. B. a coolant or charge air flows through the flat tubes and a cooling medium, eg. B. Ambient air flows over the corrugated fins. Such soldered cooling systems are used for coolant coolers for cooling an internal combustion engine or as charge air coolers for cooling the compressed intake air of internal combustion engines in motor vehicles. Radiators or condensers or evaporators are also constructed similarly, for example. Ribs can also be used in mechanically joined heat exchangers in which the ribs and the tubes of the heat exchangers are mechanically connected to one another.

The trend of development goes in the direction of higher pressures for the medium to be cooled, in particular in the coolant circuit, the flat tubes Because of the lower air pressure drop, they are extremely slim and therefore extremely unstable against increased internal pressure. The flat tubes therefore tend to "inflate", ie bulge when subjected to internal pressure. This bulge can be counteracted from the inside and outside The flat tubes are covered with gills to improve the heat transfer, which has disadvantages in terms of strength. The corrugated fins therefore buckle when the flat tubes are subjected to higher internal pressure.

It has therefore been proposed in US-A 4,693,307 to form a stiffening bead in the middle of a gill field, i. H. a roof-shaped single double gill, which simultaneously causes a flow deflection.

EP 0 547 309 B1 from the applicant discloses a corrugated fin for flat tubes, in which a stiffening bead is arranged between two gill panels and in the middle of the flat tube, i. H. where the greatest buckling stress occurs for the corrugated fin. However, this only results in a selective stiffening of the corrugated fin, which is no longer sufficient with increasing stress as a result of increased internal pressure.

It is the object of the present invention to improve a corrugated fin of the type mentioned at the outset with regard to its supporting action without impairing its thermodynamic properties such as heat transfer and pressure drop.

This object is achieved by the features of claim 1 and claim 11. According to the invention, the stiffening means are integrated in the gills, ie basically all gills of the corrugated fin contribute to the support effect. The flat tubes are thus supported over their entire length by a stiffened corrugated fin. Each individual gill advantageously has a kink-resistant profile, which gives the entire corrugated fin increased security against kinking. According to an advantageous embodiment of the invention, the profile of each gill has an S-shaped cross section. This gives the advantage of a greater section modulus against buckling without significantly increasing the air-soapy pressure drop across the corrugated fin - on the contrary. a lower pressure drop can be expected. The gill, which is S-shaped in cross-section, thus has a variable gill angle - compared to the prior art - which initially rises from a very low value to a maximum value in the middle of the gill length and then decreases again to a minimum value. This results in a "gentle" deflection of the air flow without - as in the prior art - lossy eddies occurring at the leading and trailing edge of the gills. An advantage is an unexpected combination effect in that the kink stiffness of the gills increases and whose pressure drop is reduced at the same time.

According to a further advantageous embodiment of the invention, the cross section of the gills is angled twice and has an approximately Z-shaped course, i. H. the gill angled according to the invention has three gill angles, the gill angle jumping from a low to a high value at the first kink and back to the low value at the second kink. Thus, the Z-shape has an inconsistent course of the gill angle over the gill length compared to the S-shape, which simplifies production technology. Incidentally, the advantage of increased buckling rigidity combined with a reduced pressure drop is also achieved here.

According to further advantageous refinements of the invention, advantageous angular dimensions are given both for the S-shaped and for the Z-shaped cross section of the gill. The low inflow and outflow angle is particularly advantageous because, as already mentioned, this avoids eddy formation behind the inflow and outflow edge. At the same time, the heat transfer performance of the corrugated fin is not deteriorated, since the thermal boundary layer is still started up on each leading edge of a gill. This mechanism is responsible for a large part of the heat transfer. This ultimately also has the advantage that the entire heat exchanger is improved in terms of its performance.

Embodiments of the invention are shown in the drawing and are described in more detail below. Show it

1 shows a corrugated fin with gills according to the prior art in a view from the front, FIG. 2 shows the corrugated fin according to the prior art in a plan view,

3 shows a section through the corrugated fin according to FIG. 2 along the line III-III,

4 the corrugated fin according to the prior art and its load,

5 a corrugated fin according to the invention with an S-shaped cross section, FIG. 6 a corrugated fin according to the invention with a double kink cross section,

Fig. 7 shows a detail X from Fig. 5 and

8 shows a detail Y from FIG. 6.

Fig. 1 shows a corrugated fin 1 with gills 2 seen in the air flow direction.

The corrugated fin 2 is part of a cooling system, not shown, consisting of corrugated fins and flat tubes 3, which are indicated by dashed lines. The corrugated fins are each arranged between two tubes. The tubes are in turn connected in a fluid-tight manner to header boxes at their end regions. The pipes are typically inserted into openings in the collecting box and connected to them in a fluid-tight manner. The tubes are preferably pushed into a tube plate with openings and connected in a sealed manner, so that the fluid can get from one header box through the fluid connections within the tubes to the other header box. The corrugated fin 1 and the flat tubes 3 preferably each consist of an aluminum material and are soldered to one another. However, other materials can also be used in other design variants, such as steel in particular for exhaust gas heat exchangers, copper or other alloys. 2 shows the corrugated fin 1 in a plan view, the direction of air flow being represented by an arrow L. The gills 2 form two gill arrays with front gills 2a and rear gills 2b.

Fig. 3 shows a section along the line III-III and the opposite gill angles α1 and α2 of the front gills 2a and the rear gills, 2b.

Fig. 4 shows the corrugated fin 1 according to the prior art and its loading by the flat tubes, not shown here, when these are subjected to internal pressure. The load on the corrugated fin 1 is represented by arrows P1, P2, which each act on a fin arch 1 a, 1 b. This leads to a pressure load on the rib sections between the rib arch 1 a, 1 b, d. H. also to a pressure load on the gills 2, which are therefore also subject to a buckling load. Due to the rectangular cross section of the known gills 2, there is a relatively low buckling load which causes the corrugated fin 1 to buckle according to the prior art (cf. Dubbel, Taschenbuch für den Maschinenbau, 20th edition, C 43).

5 shows a corrugated fin 5 according to the invention with front gills 6a and rear gills 6b, which have an S-shaped cross section. The S-shaped cross-section is characterized by a constantly changing gill angle from the inlet to the outlet of the air flow. An enlarged cross section is shown as detail X in FIG. 7 and is described in more detail there.

6 shows a further embodiment of the invention, namely a corrugated fin 7 with front gills 8a and rear gills 8b, which are each angled twice, ie have a double kink. The gill angle changes discontinuously in this double-knee gill 8a, 8b, ie in each case at the kink point. An enlarged view is shown as detail Y in FIG. 8 and is described in more detail there. FIG. 7 shows the detail X from FIG. 5, ie the gill 6a, which is arranged symmetrically upwards and downwards relative to a central plane e of the corrugated fin 5. The S-shape of the gill 6a has an approximately sinusoidal shape and is characterized by three sections, namely an inflow area 9, a central deflection area 10 and an outflow area 11. The slopes of the individual areas 9, 10, 11 are represented by straight lines a, b, c. There is a continuous transition between sections 9, 10, 11. The inflow section 9 forms an inflow angle αs with the central plane e, and the outflow region 11 forms an outflow angle αs with the central plane e, ie the angle between the straight lines c and e. The central cross-sectional area 10, that is to say the deflection area, forms a deflection angle βs with the center plane e (angle between the straight lines b and e). The angles αs are in a range from 0 to 10 degrees, preferably in a narrower range from 0 to 5 degrees. The deflection angle βs is in a range from 15 to 35 degrees and preferably in a range from 20 to 30 degrees. The air flow marked by an arrow L thus meets an extremely small inflow angle αs in the inflow region 9, so that no detachments and eddies form on the rear or suction side of the gill profile. The inflow angle αs, which corresponds to the gill angle α in the prior art, changes with increasing flow around the gill 6a up to the value βs and then decreases again to the value αs in the region 11. This also results in a non-detachable outflow of air. The S-shaped cross section of the gill 6a results in an increased section modulus against buckling, ie a higher permissible buckling load - in comparison to the known rectangular cross section.

FIG. 8 shows the detail Y from FIG. 6, ie the corrugated fin 7 with gills 8a, which are angled twice and have a double kink cross section or an approximately Z-shaped course. The center plane of the corrugated fin 7 is also marked with e here, ie as a reference plane for the individual angles. The cross-section of the gill 8a is divided into three sections, namely an inflow section 12, a central deflection section 13 and an outflow section 14, all three sections 12, 13, 14 being approximately rectilinear and connected to one another by radii r. The slopes of the individual sections 12, 13, 14 are marked by straight lines a, b, c and form the inflow and outflow angles αz and the deflection angle ßz with the reference plane e. The air flow is again represented by an arrow L, and it can be seen that the inflow angle αz is relatively small, so that there are no or hardly any signs of separation of the flow on the suction side of the inflow section 12 and also the deflecting section 13. The air flow can therefore also be present on the suction side of the gill 8a, which results in a low pressure drop. The inflow and outflow angles αz are in the range from 0 to 25 or preferably in the range from 5 to 15 degrees, and the deflection angle βz is in the range from 15 to 35 degrees or preferably in the range from 20 to 30 degrees. This Z-shaped profile of the gill 8a also results in an increased resistance moment against buckling, which, with the number of gills, adds up to an increased total resistance moment against buckling for the entire rib.

The manufacture of the gills described above, i. H. both with S-profile and with Z-profile is carried out in a similar manner as in the prior art, i. H. using so-called rib cutting rollers, which cut and shape the gills from a flat sheet metal strip.

Claims

Patent claims

1.Fin, in particular corrugated fin, in particular for a flat tube heat exchanger, in particular a coolant or charge air cooler for motor vehicles, the fin being arranged between flat tubes of the heat exchanger or being arranged perpendicularly to them and being integrally or mechanically connected to them, with gills and can be flowed over by air and has molded-in stiffening means, characterized in that the stiffening means are integrated in the gills (6a, 6b; 8a, 8b).

2. Rib according to claim 1, characterized in that the gills (6a, 6b; 8a, 8b) have a kink-resistant profile which is different from a straight line or a rectangular profile.

3. Rib according to claim 2, characterized in that the profile has an S-shaped cross section (6a) with two curves.

4. Rib according to claim 2, characterized in that the profile has a double, triple or multiple angled, for example approximately Z-shaped cross section (8a).

Rib according to claim 2, characterized in that the profile has a simply angled, approximately V-shaped cross-section (8a).

6. Rib according to claim 3, 4 or 5, characterized in that the cross section (6a; 8a) has an inflow and an outflow region (9, 11; 12, 14) and a deflection region (10; 13) arranged between the two, the inflow and outflow areas each have an approximately equal inflow and outflow angle (αs, αz) and the deflection area has a deflection angle (ßs, ßz) and that the deflection angle is greater than the inflow and outflow angle, i. H. ßs> αs and ßz> αz.

7. Rib according to at least one of the preceding claims, characterized in that the following ranges apply to the angles αs and βs:

0 αs <10 degrees and 15 ßs ≤ 35 degrees.

8. Rib according to at least one of the preceding claims, characterized in that the following ranges apply to the angles αs and βs:

0 αs 5 degrees and 20 ßs <30 degrees.

9. rib according to at least one of the preceding claims ,, da-. characterized in that the following ranges apply to the angles αz and ßz:

0 αz <25 degrees and 15 ßz ≤ 35 degrees. ,

10. Rib according to at least one of the preceding claims, characterized in that the following ranges apply to the angles αz and βz: 5 αz ≤ 15 degrees and 20 ßz <30 degrees.

11. Heat exchanger with manifolds and with these fluid-tightly connected fluid channels, such as pipes, the pipes being tightly received in openings in the manifolds, with an inlet and an outlet, ribs being arranged between the pipes or perpendicular to the pipes, thereby characterized in that the ribs are designed according to at least one of the preceding claims.