U.S. patent application number 17/168902 was filed with the patent office on 2021-08-12 for inner fin and flat tube including an inner fin.
This patent application is currently assigned to MAHLE International GmbH. The applicant listed for this patent is MAHLE International GmbH. Invention is credited to Frank-Heiner SCHENK, Matthias SEITZ.
Application Number | 20210247149 17/168902 |
Document ID | / |
Family ID | 1000005479232 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210247149 |
Kind Code |
A1 |
SCHENK; Frank-Heiner ; et
al. |
August 12, 2021 |
INNER FIN AND FLAT TUBE INCLUDING AN INNER FIN
Abstract
An inner rib, in particular for a flat tube, in particular of a
heat exchanger, made from a metallic flat strip, which is shaped in
a wavy modulated manner, having a large number of wave crests and
wave troughs, which are each arranged alternately in a longitudinal
direction of the inner fin, an essentially straight, web-like fin
area being provided between one wave crest and an adjacent wave
trough and connecting the wave crest to the wave trough, the
metallic flat strip having a first strip thickness L1, which is
essentially constant in the area of the wave crests and the wave
troughs, the flat metallic strip having a second strip thickness
L2, which is provided in the area of the web-like fin area, L2
being smaller than L1.
Inventors: |
SCHENK; Frank-Heiner;
(Stuttgart, DE) ; SEITZ; Matthias; (Oberkochen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAHLE International GmbH |
Stuttgart |
|
DE |
|
|
Assignee: |
MAHLE International GmbH
Stuttgart
DE
|
Family ID: |
1000005479232 |
Appl. No.: |
17/168902 |
Filed: |
February 5, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 1/0535 20130101;
F28F 1/40 20130101; F28F 2275/06 20130101; F28F 2275/025
20130101 |
International
Class: |
F28F 1/40 20060101
F28F001/40; F28D 1/053 20060101 F28D001/053 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2020 |
DE |
10 2020 201 556.2 |
Claims
1. An inner fin for a flat tube of a heat exchanger comprising: a
metallic flat strip formed in a wavy modulated manner; a plurality
of wave crests and wave troughs formed in the metallic flat strip,
the plurality of wave crests and wave troughts being arranged
alternately in a longitudinal direction of the inner fin; and an
essentially straight, web-like fin area formed between one wave
crest and an adjacent wave trough, the web-like fin area connecting
a wave crest to a wave trough, wherein the metallic flat strip has
a first strip thickness L1, which is essentially constant in an
area of the wave crests and the wave troughs, wherein the flat
metallic strip has a second strip thickness L2, which is formed in
the area of the web-like fin area, and wherein L2 is smaller than
L1.
2. The inner fin according to claim 1, wherein the metallic flat
strip has a first strip thickness L1, which is essentially constant
in the entire area of the wave crests and the wave troughs, and
wherein the flat metallic strip has a second strip thickness, which
is essentially formed in the entire area of the web-like fin
area.
3. The inner fin according to claim 1, wherein the metallic flat
strip is curved in the area of the wave crests and the wave
troughs.
4. The inner fin according to claim 1, wherein the strip thickness
reduction R from the first strip thickness L1 to the second strip
thickness L2 takes place in a range from 0.2*L1 to 0.9*L1, i.e.
0.2*L1<L2<0.9*L1, in particular 0.3*L1<L2<0.7*L1 or
further in particular 0.35*L1<L2<0.55*L1 or further in
particular L2=0.5*L1.
5. The inner fin according to claim 1, wherein the metallic flat
strip has two oppositely situated wide sides, between which the
strip thickness is determined, the strip thickness reduction R from
the first strip thickness L1 to the second strip thickness L2 being
carried out on at least one wide side of the flat strip or being
carried out on both oppositely situated wide sides of the flat
strip.
6. The inner fin according to claim 5, wherein the strip thickness
reduction R from L1 to L2 is carried out on both oppositely
situated wide sides of the flat strip by a constriction,
approximately the same amount of the proportional strip thickness
reduction R1, R2 of approximately R1=(L1-L2)/2 and R2=(L1-L2)/2
being present on both wide sides.
7. The inner fin according to claim 5, wherein the strip thickness
reduction R from L1 to L2 is present on both sides of the neutral
fibers of the strip, in particular approximately the same amount of
proportional strip thickness reduction R1, R2 of approximately
R1=(L1-L2)/2 and R2=(L1-L2)/2 is present on both sides of the
neutral fibers.
8. The inner fin according to claim 1, wherein the metallic flat
strip has a first strip thickness L1, which is essentially constant
in the entire area of the wave crests and the wave troughs, and the
flat metallic strip has a second strip thickness L2, which is
essentially formed in the entire area of the web-like fin area.
9. A flat tube comprising: a tube wall having two oppositely
situated wide sides and two oppositely situated narrow sides; a
tube interior; and an inner fin according to claim 1, the inner fin
being arranged in the tube interior, wherein the wave crests abut
one of the two wide sides of the tube wall, wherein the wave
troughs abut the other of the two wide sides or the wave crests
connected to one of the two wide sides of the tube wall, and
wherein the wave troughs are connected to the other of the two wide
sides via, in particular soldered, welded or glued.
10. The flat tube according to claim 9, wherein the wave crests are
soldered on one of the two wide sides of the tube wall, and the
wave troughs are soldered on the other of the two wide sides,
wherein solder menisci made from solder material is formed between
the strip and the wide sides, and wherein the web-like fin area has
the second strip thickness L2 being arranged between the solder
menisci.
Description
[0001] This nonprovisional application claims priority under 35
U.S.C. .sctn. 119(a) to German Patent Application No. 10 2020 201
556.2, which was filed in Germany on Feb. 7, 2020 and which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to an inner fin and a flat
tube, in particular for a heat exchanger, in particular for a motor
vehicle.
Description of the Background Art
[0003] In heat exchanges for motor vehicles, flat tubes are known,
in which an inner fin is inserted or introduced into the tube
interior of the flat tube, which abuts and is soldered on the
oppositely situated wide sides of the flat tube, so that the flat
tube achieves an increased inner pressure resistance. For this
purpose, the inner fin is modulated, for example in a wavy manner,
including a large number of wave crests and wave troughs, which are
each alternately soldered to the wide sides of the flat tube in an
abutting manner.
[0004] The inner fin improves the inner pressure resistance of the
flat tube and also increases the heat transfer rate from a first
fluid flowing through the flat tube to a second fluid flowing
around the flat tube and back again.
[0005] Modern motor vehicles are increasingly optimized for lower
consumption values and/or lower emissions. This is particularly
true for motor vehicles with internal combustion engines. The
orientation toward low consumption values is, however, also highly
relevant for electric vehicles or hybrid vehicles, since the low
consumption of electrical energy per kilometer driven, in
particular, is relevant to the cost of driving the motor vehicle
and also determines the maximum range of the motor vehicle.
[0006] In this context, however, the focus is on the flat tube in
terms of the cost and the weight of the heat exchanger, due to the
flat tube's frequent use in a heat exchanger.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide an inner fin, which permits a good heat transfer and
simultaneously a good inner pressure resistance of a flat tube
compared to the prior art, and the inner fin nevertheless being
able to be manufactured cost-effectively with a reduced use of
materials. The object is also to provide a flat tube including an
inner fin, which is cost-effectively strengthened with little use
of materials and nevertheless has a good inner pressure resistance
and good heat transfer.
[0008] An exemplary embodiment of the invention relates to an inner
rib, in particular for a flat tube, in particular of a heat
exchanger, made from a metallic flat strip, which is shaped in a
wavy modulated manner, having a large number of wave crests and
wave troughs, which are each arranged alternately in a longitudinal
direction of the inner fin, an essentially straight, web-like fin
area being provided between one wave crest and an adjacent wave
trough and connecting the wave crest to the wave trough, the
metallic flat strip having a first strip thickness L1, which is
essentially constant in the area of the wave crests and the wave
troughs, the flat metallic strip having a second strip thickness
L2, which is formed in the area of the web-like fin area, L2 being
smaller than L1. Material is thereby saved in an intermediate area
between the wave crests and the wave troughs to the extent that a
significant weight reduction is achieved, while maintaining a
sufficiently good inner pressure resistance and heat transfer.
[0009] In one exemplary embodiment, it is advantageous if the
metallic flat strip has a first strip thickness L1, which is
essentially constant in the entire area of the wave crests and the
wave troughs, and the flat metallic strip has a second strip
thickness L2, which is essentially formed in the entire area of the
web-like fin area. Material is thereby saved in the entire
intermediate area between the wave crests and the wave troughs to
the extent that a significant weight reduction is achieved, while
maintaining a sufficiently good inner pressure resistance and heat
transfer.
[0010] It is particularly advantageous if the metallic flat strip
is curved in the area of the wave crests and the wave troughs. The
area of the connection to the flat tube may thereby occur in the
curved area, advantageously by soldering.
[0011] It is particularly advantageous if strip thickness reduction
R from first strip thickness L2 to second strip thickness L2 takes
place in a range from 0.2*L1 to 0.9*L1, i.e.
0.2*L1<L2<0.9*L1, in particular 0.3*L1<L2<0.7*L1 or
further in particular 0.35*L1<L2<0.55*L1 or further in
particular L2=0.5*L1. The intended objectives with respect to inner
pressure resistance, material savings as well as with regard to an
improvement in the pressure drop in the tube interior are achieved
thereby.
[0012] It is also expedient if the metallic flat strip has two
oppositely situated wide sides, between which the strip thickness
may be determined, strip thickness reduction R from first strip
thickness L1 to second strip thickness L2 being carried out on at
least one wide side of the flat strip or being carried out on both
oppositely situated wide sides of the flat tube. An asymmetrical or
a symmetrical stiffness behavior may be achieved thereby, the
arrangement of the strip thickness reduction also depending on the
manufacturing of the strip thickness reduction, for example by
rolling the metallic strip.
[0013] It is also expedient if strip thickness reduction R from L1
to L2 is carried out on both oppositely situated wide sides of the
flat tube by a constriction, approximately the same amount of
proportional strip thickness reduction R1, R2 of approximately
R1=(L1-L2)/2 and R2=(L1-L2)/2 being present. A favorable force
distribution in the desired material reduction is achieved
thereby.
[0014] It is further advantageous if strip thickness reduction R
from L1 to L2 is present on both sides of the neutral fibers of the
strip, in particular approximately the same amount of proportional
strip thickness reduction R1, R2 of approximately R1=(L1-L2)/2 and
R2=(L1-L2)/2 is present on both sides of the neutral fibers. A
favorable force distribution in the desired material reduction is
achieved thereby.
[0015] It is also advantageous if the metallic flat strip has a
first strip thickness L1, which is essentially constant in the
entire area of the wave crests and the wave troughs, and the flat
metallic strip has a second strip thickness L2, which is
essentially formed in the entire area of the web-like fin area. A
favorable force distribution in the desired material reduction is
achieved thereby.
[0016] An exemplary embodiment of the invention also relates to a
flat tube, including a tube wall and a tube interior, the tube wall
having two oppositely situated wide sides and two oppositely
situated narrow sides, an inner fin according to the invention
being arranged in the tube interior, the wave crests abutting one
of the two wide sides of the tube wall, and the wave troughs
abutting the other of the two wide sides, in particular the wave
crests being connected to one of the two wide sides of the tube
wall, and the wave troughs being connected to the other of the two
wide sides, in particular soldered, welded or glued.
[0017] It is advantageous if the wave crests are soldered on one of
the two wide sides of the tube wall, and the wave troughs are
soldered on the other of the two wide sides, solder menisci made
from solder material forming between the strip and the wide sides,
the web-like fin area having second strip thickness L2 being
arranged between the solder menisci.
[0018] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes, combinations, and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus, are
not limitive of the present invention, and wherein:
[0020] FIG. 1 shows a schematic sectional representation of a flat
tube;
[0021] FIG. 2 shows a schematic partial sectional representation of
a flat tube, including an inner fin according to the invention;
[0022] FIG. 3 shows a detail of the section of the inner fin;
and
[0023] FIG. 4 shows a further detail of the section of the inner
fin.
DETAILED DESCRIPTION
[0024] FIG. 1 shows a sectional view of a flat tube 1, including a
tube wall 2 and a tube interior 3. Tube wall 2 is formed, for
example, from a sheet material strip 4, which is deformed. Sheet
material strip 4 may thus be designed as a folding tube and be
soldered, as illustrated, or the flat tube may alternatively also
be designed as a welded tube.
[0025] Tube wall 2 has two oppositely situated wide sides 5 and two
oppositely situates narrow sides 6, which are arranged alternately
in a circumferential manner. Flat tube 1 in the illustrated
exemplary embodiment is closed on one of the two narrow sides 6, an
overlap of end areas of sheet material strip 4 being formed, which
overlap each other and are soldered in this location.
[0026] An inner fin 7 is arranged in tube interior 3. Inner fin 7
is formed from a metallic flat strip, which is, for example, rolled
to form its structure. For example, metallic strip is formed from
aluminum, an aluminum alloy, from steel, etc.
[0027] Inner fin 7 is provided with a wavy design, formed in a
modulated manner, and has a wave structure, which forms a large
number of wave crests 8 and wave troughs 9. The large number of
wave crests 8 and wave troughs 9 are each alternately arranged in a
longitudinal direction of inner fin 7, an essentially straight,
web-like fin area 10 being provided between one wave crest 8 and an
adjacent wave trough 9, which connects wave crest 8 to wave trough
9. A large number of adjacent web-like fin areas 10 are formed
thereby, which divide interior 3 of flat tube 1 into fluid paths
11. Web-like fin areas 10 may be closed over a wide area or be
formed with interruptions to permit a cross flow.
[0028] Wave crests 8 abut one of the two wide sides 5 of tube wall
2, and wave troughs 9 abut the other of the two wide sides 5.
Advantageously and optionally, wave crests 8 are connected to one
of the two wide sides 5 of tube wall 2, and wave troughs 9 are
connected to the other of the two wide sides 5, in particular
soldered, welded or glued.
[0029] In one preferred exemplary embodiment, wave crests 8 are
soldered on one of the two wide sides 5 of tube wall 2, and wave
troughs 9 are soldered to the other of the two wide sides 5, solder
menisci 12 made from solder material being formed between the strip
of inner fin 7 and wide sides 5 of flat tube 1, as is apparent in
FIG. 2.
[0030] Web-like fin area 10 is arranged between solder menisci 12
formed on oppositely situated wide sides 5. It is apparent in FIGS.
1 and 2 that the wall thickness of sheet metal strip 4 of tube wall
2 of flat tube 1 is significantly thicker than the wall thickness
of metallic flat strip of inner fin 7, i.e., for example it is at
least twice as thick, three times as thick or more.
[0031] Upon closer observation of inner fin 7, it is apparent in
FIG. 2 that the metallic flat strip of inner fin 7 has a first
strip thickness L1, which is provided in the area of wave crests 8
and wave troughs 9 and which is essentially constant.
[0032] The flat metallic strip of inner fin 7 also has a second
strip thickness L2, which is formed in the area of web-like fin
area 10, L2 being smaller than L1.
[0033] In one advantageous exemplary embodiment, it is optional and
expedient if the metallic flat strip of inner fin 7 has a first
strip thickness L1, which is essentially constant in the entire
area of wave crests 8 and wave troughs 9, the flat metallic strip
of the inner fin having a second strip thickness L2, which is
essentially provided with a constant design in the entire area of
web-like fin area 10.
[0034] It is apparent from FIG. 2 that the metallic flat strip of
inner fin 7 is provided with a curved design in the area of wave
crests 8 and wave troughs 9. The curvature may have a radius of
curvature or assume multiple radii of curvature.
[0035] The transition from first strip thickness L1 to second strip
thickness L2 advantageous takes place in the transition from curved
wave trough 9 to essentially straight, web-like rib area 10 and
advantageously takes place in the transition from curved wave crest
8 to essentially straight, web-like fin area 10, as is also
apparent in FIG. 2.
[0036] Strip thickness reduction R from first strip thickness L1 to
second strip thickness L2 takes place in a range from 0.2*L1 to
0.9*L1, i.e. 0.2*L1<L2<0.9*L1. It is particularly
advantageous if strip thickness reduction R from first strip
thickness L1 to second strip thickness L2 is in a range from 0.3*L1
to 0.7*L1, so that 0.3*L1<L2<0.7*L1, or it is further
advantageous if strip thickness reduction R from first strip
thickness L1 to second strip thickness L2 is in a range from
0.35*L1 to 0.55*L1, and 0.35*L1<L2<0.55*L1. It may also be
advantageous if L2=0.5*L1.
[0037] Upon closer examination, the metallic flat strip of inner
fin 7 has two oppositely situated wide sides 13, between which the
strip thickness may be determined, strip thickness reduction R from
first strip thickness L1 to second strip thickness L2 being carried
out on at least one wide side 13 of the flat strip of inner fin 7
or, as illustrated in FIGS. 2 through 4, is carried out on both
oppositely situated wide sides 13 of the flat strip of inner fin
7.
[0038] According to FIGS. 2 through 4, strip thickness reduction R
from L1 to L2 is carried out on both oppositely situated wide sides
13 of the flat strip of inner fin 7 by a constriction. For example,
approximately the same amount of proportional strip reduction R1,
R2 of approximately R1=(L1-L2)/2 and R2=(L1-L2)/2 is optionally
carried out on both wide sides 13.
[0039] Correspondingly, strip thickness reduction R from L1 to L2
is proportionately present on both sides of the neutral fibers 14
of the strip of inner fin 7, in particular approximately the same
amount of proportional strip thickness reduction R1, R2 of
approximately R1=(L1-L2)/2 and R2=(L1-L2)/2 is present on both
sides of neutral fibers 14. R=R1+R2 therefore applies.
[0040] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are to be included within the scope of the following
claims.
* * * * *