U.S. patent application number 10/576523 was filed with the patent office on 2007-01-25 for heat exchanger.
This patent application is currently assigned to BEHR GmbH & CO, KG. Invention is credited to Peter Geskes, Daniel Hendrix, Rainer Lutz, Ulrich Maucher, Jens Richter, Martin Schindler, Michael Schmidt.
Application Number | 20070017661 10/576523 |
Document ID | / |
Family ID | 34524041 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070017661 |
Kind Code |
A1 |
Geskes; Peter ; et
al. |
January 25, 2007 |
Heat exchanger
Abstract
The invention relates to a heat exchanger (1), especially for
motor vehicles, comprising a housing (2) and at least one pipe (3)
disposed inside said housing (2). The heat exchanger is
characterized in that structures (4) are provided in the area
between the pipes (3) and the housing (2) and/or between the pipes
(3).
Inventors: |
Geskes; Peter; (Stuttgart,
DE) ; Hendrix; Daniel; (Stuttgart, DE) ; Lutz;
Rainer; (Steinheim, DE) ; Maucher; Ulrich;
(Korntal-Munchingen, DE) ; Richter; Jens;
(Grossbotwar, DE) ; Schindler; Martin; (Kurnach,
DE) ; Schmidt; Michael; (Bietigheim-Bissingen,
DE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GmbH & CO, KG
|
Family ID: |
34524041 |
Appl. No.: |
10/576523 |
Filed: |
October 20, 2004 |
PCT Filed: |
October 20, 2004 |
PCT NO: |
PCT/EP04/11867 |
371 Date: |
April 20, 2006 |
Current U.S.
Class: |
165/166 ;
165/157 |
Current CPC
Class: |
F28D 21/0003 20130101;
F28F 1/14 20130101; F28D 7/1653 20130101; F28F 1/126 20130101; F28F
9/0268 20130101; Y02T 10/16 20130101; Y02T 10/12 20130101 |
Class at
Publication: |
165/166 ;
165/157 |
International
Class: |
F28F 3/00 20060101
F28F003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2003 |
DE |
103 49 259.3 |
Oct 15, 2004 |
EP |
04024691.0 |
Claims
1. A heat exchanger, in particular for motor vehicles, having a
housing and at least one tube arranged in the housing, wherein
structures are provided in the region between the tubes and the
housing and/or between the individual tubes.
2. The heat exchanger as claimed in claim 1, wherein the structures
are formed from sheet-metal structures arranged between the tubes
and the housing and/or between the individual tubes.
3. The heat exchanger as claimed in claim 2, wherein the
sheet-metal structures are finned metal plates, studded metal
plates or separate tubes.
4. The heat exchanger as claimed in claim 1, wherein the structures
are formed directly on the housing and/or on the tubes.
5. The heat exchanger as claimed in claim 4, wherein the structures
are produced by means of stamping.
6. The heat exchanger as claimed in claim 1, wherein the structures
are fixedly joined to the housing and/or the tubes, in particular
by soldering.
7. The heat exchanger as claimed in claim 1, wherein the tubes are
at least in part formed by flat tubes.
8. The heat exchanger as claimed in claim 1, wherein the tubes have
supporting studs on the tube outer side.
9. The heat exchanger as claimed in claim 1, wherein the tubes have
a tube surface on the inner and/or outer side which is structured
so as to generate turbulence.
10. The heat exchanger as claimed in claim 1, wherein the
structures at least in part have an inhomogeneous structure.
11. The heat exchanger as claimed in claim 1, wherein the
structures are at least partially toothed.
12. The heat exchanger as claimed in claim 1, wherein the housing
is formed in two or more parts.
13. The heat exchanger as claimed in claim 1, wherein a medium
which is to be cooled flows within the tubes, and a coolant flows
in the space between the housing and the tubes and structures.
14. The heat exchanger as claimed in claim 1, wherein the
structures are arranged on the coolant side in the housing of the
heat exchanger.
15. The heat exchanger as claimed in claim 1, wherein the
structures are arranged in the interior of at least one tube.
16. The heat exchanger as claimed in claim 1, wherein the
structures are formed as at least one fin which is in particular
straight or of undulating depth and/or in particular has gills.
17. The use of the heat exchanger as claimed in claim 1, wherein as
an exhaust-gas heat exchanger or a charge-air cooler of a motor
vehicle.
Description
[0001] The invention relates to a heat exchanger, in particular for
a motor vehicle, as described in the preamble of claim 1.
[0002] Extensive measures, such as for example increased
supercharging, more accurate influencing of the combustion
conditions, are required to satisfy the increase in demands imposed
on modern engines with regard to reduction of emissions and fuel
consumption. This also leads to more arduous conditions of use for
motor vehicle heat exchangers, specifically higher gas and coolant
pressures, increased temperatures and greater volumetric
throughputs. At the same time, the demands imposed on power density
and service life are also increasing. In some cases, therefore, new
cooling concepts are required. For example, in the case of
charge-air coolers, the air/air coolers which have customarily been
used are at least in part being replaced by air/liquid coolers in
order to achieve the required performance and power densities
required on account of the high engine supercharging. In the case
of exhaust-gas heat exchangers, ever higher exhaust-gas
recirculation rates are required, involving likewise evermore
arduous operating conditions in terms of pressures, temperatures
and power densities. Therefore, ever higher mechanical stresses are
encountered in modern heat exchangers, in particular with regard to
pressure and oscillations.
[0003] High temperature differences between the primary medium,
which is to be cooled and is generally in gas form, and the cooling
secondary medium, which is generally in liquid form, lead to
different levels of component heating on the primary side and
secondary side. In the case of exhaust-gas heat exchangers, the
temperature difference may amount to over 700 K, and in the case of
charge-air coolers up to 300 K. On account of different thermal
longitudinal expansions between the primary and secondary sides,
considerable thermal stresses are produced. In the event of rapid
changes in operating state, these thermal stresses may also be
exacerbated by uneven temperature distributions (thermal
shocks).
[0004] Moreover, on account of higher heat exchanger power
densities, the risk of the coolant boiling rises, which can lead to
increased power losses and shorter service lives.
[0005] Finally, the processes and materials used are subject to
considerable restrictions on account of the occurrence of highly
corrosive medium, e.g. condensate from the exhaust gas in the case
of exhaust-gas heat exchangers, which given the ever increasing
demands imposed on power density leads to ever greater problems in
providing a long-term technical solution for balancing sufficient
resistance of the flow channels to internal and external pressures
with sufficient resistance to induced oscillations and thermal
stresses, while avoiding boiling.
[0006] It is an object of the invention to provide an improved heat
exchanger.
[0007] This object is achieved by the heat exchanger having the
features of claim 1. Advantageous configurations form the subject
matter of the subclaims.
[0008] The invention provides a heat exchanger having a housing and
at least one tube arranged in the housing, structures being
provided between the tubes and the housing and/or between the
individual tubes. The primary medium flows through the tubes. The
secondary medium is passed within the spaces between the individual
tubes and/or between the tubes and the housing, in which the
structures are also arranged. The structures increase the strength
by providing a stiffening action with respect to internal and
external pressures acting on the tubes. Moreover, the coupling
between the tubes and the housing brings about continuous
compensation for the thermal stresses between primary and secondary
sides over the entire length of the cooler, so that the stresses at
the ends of the tubes are considerably reduced. The structures are
also used for fluid diverting and distribution within the heat
exchanger. Furthermore, the finned metal plates allow better heat
transfer, with the result that thermal stresses can be reduced by
the improved heat transfer. The increased heat transfer surface
area leads to better cooling of the tubes, and boiling can be
avoided. Overall, therefore, the result is a considerable increase
in the power density of the heat exchanger compared to conventional
heat exchangers without structures. As the structures, it is
preferable for sheet-metal structures in the form of separate
tubes, finned metal plates, studded metal plates or the like to be
introduced. The heat exchanger may in particular be an exhaust-gas
heat exchanger or charge-air cooler, but may also be another form
of heat exchanger, for example another gas-liquid heat exchanger,
in which hot gas flows through the heat exchanger (cooler) in tubes
in order to be cooled, a liquid-gas heat exchanger, in which cold
gas flows through the heat exchanger (heater) in tubes in order to
be heated, or a liquid-liquid heat exchanger. As an alternative to
using sheet-metal structures, it is also possible for the tubes
and/or the housing to be correspondingly designed with structures,
i.e. in particular the tube surface may be of fin-like and/or
stud-like design. The structures preferably have a height of from 1
mm to 5 mm, preferably 1 mm to 3 mm, particularly preferably 1.5
mm. The pitch L of the structures is preferably 0.1 to 6 times,
particularly preferably 0.5 to 4 times, the structure height h. The
transverse pitch Q is preferably 0.15 to 8 times, particularly
preferably 0.5 to 5 times, the structure height h. The ratio of
passage height between the tubes and passage height within the tube
in the region of structures is preferably from 0.1 to 1, preferably
from 0.2 to 0.7. The hydraulic diameter between the tubes in the
region with structures is preferably from 0.5 mm to 10 mm, for
preference from 1 mm to 5 mm.
[0009] It is preferable for the structures to be fixedly joined to
the housing and/or the tubes, in particular by soldering. In this
case, in particular a fixed connection over a large part of the
length of the heat exchanger, with or without interruptions, for
example to improve distribution of coolant, is provided. The fixed
connection very efficiently increases the resistance to external
pressure (excess pressure on the secondary side), since the
structures provided high rods which prevent the tube from
collapsing. Furthermore, oscillations in the relatively labile
tubes of conventional heat exchangers are damped by the structures,
and the thermal stresses are very efficiently equalized.
Furthermore, the fixed connection assists with the heat transfer
from the tubes to the structures, resulting in better cooling of
the tubes. Moreover, the number of tubes can be reduced by an
improved heat transfer, so that the production costs can be
lowered.
[0010] The tubes are preferably at least in part formed by flat
tubes. Flat tubes in this context have a significantly better
thermodynamic performance than round tubes but have a lower ability
to withstand pressure, and consequently measures for increasing the
ability to withstand pressure are required for flat tubes, such as
in accordance with the invention a supporting structure on the
outer side of the tubes. The flat tubes in particular have an
approximately rectangular cross section with rounded corners.
Furthermore, it is possible to provide single-piece rectangular
tubes. These may have a longitudinal seam which may be welded, for
example laser-welded, friction-welded, induction-welded, or
soldered. The rectangular tubes may also be constructed from shells
which are welded or soldered together. The tubes may also have any
other desired form, for example oval, and/or may have lateral tabs
which are soldered and/or welded. Furthermore, to compensate for
tolerances between housing and tubes and the structures arranged
between them, the tubes can be of slightly convex design. It is
also possible for turbulators (winglets) to be provided in and/or
on the tubes. The tube surface (inner and/or outer) may also be
structured so as to generate turbulence.
[0011] It is preferable for the structures at least in part to have
an inhomogeneous construction, with the result that coolant can be
supplied in targeted fashion to critical regions, so that
overheating or boiling can be avoided. A correspondingly increased
supply of coolant can also be achieved by the partial emission of
structures. The pressure loss in the heat exchanger and the
transverse distribution of the coolant in the heat exchanger can be
optimized by these measures. The regions with inhomogeneous
structures are preferably in the inlet and/or outlet region of the
fluid. They are used in particular for flow diversion and to
minimize the pressure loss.
[0012] The stability of the structures can be increased by at least
partial toothing, and furthermore the flow paths of the coolant can
thereby be optimized.
[0013] To simplify the structure of the heat exchanger, the housing
is preferably formed in two or more parts, in particular as a
U-shaped shell with a cover, in which case a water chamber can be
integrated in the cover. In principle, however, a single-part
construction, for example with an integrally formed water chamber,
is also possible.
[0014] Structures can also be provided in the tubes themselves, in
which case all the abovementioned structures which may be provided
between the tubes can also be integrated in the tubes. The
structures are preferably formed by finned metal plates or studded
metal plates which are joined to the tube for example by welding,
soldering or clamping. The structures preferably have a height of
from 1 mm to 5 mm, preferably 1 mm to 3 mm, particularly preferably
1.5 mm. The pitch L of the structures is preferably 0.5 to 6 times
the structure height h. The transverse pitch Q is preferably 0.5 to
8 times the structure height h. The hydraulic diameter in the tube
in the region having structures is preferably from 0.5 mm to 10 mm,
for preference 1 mm to 5 mm.
[0015] The text which follows provides a more detailed explanation
of the invention on the basis of an exemplary embodiment and with
reference to the drawing, in which:
[0016] FIG. 1 shows a section through an exhaust-gas heat
exchanger,
[0017] FIG. 2 shows a perspective view of the heat exchanger from
FIG. 1,
[0018] FIG. 3 shows a diagrammatic perspective view of a finned
metal plate,
[0019] FIG. 4 shows a diagrammatic perspective view of a finned
metal plate in accordance with a variant, and
[0020] FIG. 5a-d show a number of variants of inlet regions.
[0021] An exhaust-gas heat exchanger 1 has a two-part housing 2 and
a plurality of tubes 3 arranged in this housing 2. Finned metal
plates 4 are provided between the individual tubes 3 and between
the housing 2 and the tubes 3 as structures, these finned metal
plates 4 in accordance with the present exemplary embodiment being
toothed, as illustrated in FIG. 3 and described in more detail
below. The tubes 3 are in the present case flat tubes.
[0022] The exhaust gas which is to be cooled and comes from the
engine (gaseous primary medium) is passed through the individual
tubes 3; the direction of flow is indicated by two solid arrows in
FIG. 2. The housing 2 in which the tubes 3 are arranged comprises a
U-shaped first housing part 2' and a housing cover 2'' which is
fitted onto the first housing part 2' from above. Two coolant
connection pieces 5 are provided in the housing cover 2'' as inlet
and outlet for the coolant (liquid secondary medium), the direction
of flow of the coolant in co-current operation being represented by
dashed arrows in FIG. 2. Flow in counter-current mode is also
possible, for which purpose the direction of flow is reversed.
Since the coolant is passed through the housing 2 and around the
tubes 3, the finned metal plates 4 are arranged on the coolant
side.
[0023] The finned metal plates 4 formed with straight toothing make
it easy for the coolant to pass through in the direction of the
arrow represented by a solid line in FIG. 3 and more difficult for
the coolant to pass through in the direction indicated by a dashed
arrow in FIG. 3. The flow can be influenced by changing the
longitudinal pitch L and transverse pitch Q as well as the fin
height h. In addition to a straight toothing, oblique toothing is
also possible. Given a suitable configuration of the individual
finned metal plates 4, these plates can also assist the passage of
coolant in targeted fashion at particularly critical locations, for
which purpose the finned metal plates 4 are inhomogeneous at least
in regions.
[0024] FIG. 4 illustrates a simple variant of a finned metal plate
with a fin running in a straight direction which has a longitudinal
pitch L of 2.4 mm and a fin or structure height h of 1.5 mm. The
finned metal plate may also be bent from a perforated metal plate,
so that the individual corrugation flanks are permeable on account
of the perforations.
[0025] According to a variant which is not illustrated in the
drawing, a corresponding construction is used for a charge-air
cooler.
[0026] FIG. 5a-d show various inhomogeneous regions of the
structures which form the finned metal plates 4. These effect
better distribution of the fluid as it flows in. According to the
first variant, illustrated in FIG. 5a, transverse distribution
passages are provided by deformation or stamping. According to the
variants illustrated in FIGS. 5b and 5c, the finned metal plates 4
have been partially cut away. FIG. 5d shows a variant with a
special distributor structure formed on the finned metal plate 4.
An inhomogeneous region corresponding to FIG. 5a to 5d may also be
provided on the outflow side.
* * * * *