U.S. patent application number 17/147499 was filed with the patent office on 2022-07-14 for flat tube and heat exchanger.
This patent application is currently assigned to MAHLE International GmbH. The applicant listed for this patent is MAHLE International GmbH. Invention is credited to Scott Kent, Robert Louis Runk.
Application Number | 20220221226 17/147499 |
Document ID | / |
Family ID | 1000005489479 |
Filed Date | 2022-07-14 |
United States Patent
Application |
20220221226 |
Kind Code |
A1 |
Runk; Robert Louis ; et
al. |
July 14, 2022 |
FLAT TUBE AND HEAT EXCHANGER
Abstract
A flat tube for a heat exchanger has a tube body with an outer
top and an outer bottom surface arranged opposite one another at a
thickness of the tube body and two outer side surfaces arranged
opposite one another at a width of the tube body and connecting the
outer top and bottom surfaces. The tube body has a heat exchange
portion extending along an extension direction, an angled portion
extending along an transverse direction inclined relative to the
extension direction, and a bent portion connecting the heat
exchange portion to the angled portion. The angled portion is
arranged at a distance from the heat exchange portion in an offset
direction. The bent portion has a first end region facing the heat
exchange portion with a first bend counter to the offset direction
and a second end region facing the angled portion with a second
bend in the offset direction.
Inventors: |
Runk; Robert Louis;
(Lockport, NY) ; Kent; Scott; (Albion,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAHLE International GmbH |
Stuttgart |
|
DE |
|
|
Assignee: |
MAHLE International GmbH
|
Family ID: |
1000005489479 |
Appl. No.: |
17/147499 |
Filed: |
January 13, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 1/0471 20130101;
F28D 1/0417 20130101; F28D 2001/0273 20130101 |
International
Class: |
F28D 1/04 20060101
F28D001/04; F28D 1/047 20060101 F28D001/047 |
Claims
1. A flat tube (1) for a heat exchanger (30), comprising a tube
body (2) delimiting at least one coolant channel (3) for a coolant
or a refrigerant, the tube body having an outer top surface (4) and
an outer bottom surface (5) arranged opposite one another at a
thickness (T) of the tube body (2) and having two outer side
surfaces (6) arranged opposite one another at a width (W) of the
tube body (2), the outer side surfaces (6) connecting the outer top
to the outer bottom (4, 5) surface, wherein the tube body (2) has a
heat exchange portion (7) extending along an extension direction
(8), wherein the tube body (2) has an angled portion (9) extending
along an transverse direction (10) that is inclined with respect to
the extension direction (8), wherein the tube body (2) has a bent
portion (11) connecting the heat exchange portion (7) to the angled
portion (9), wherein the angled portion (9) is arranged at a
distance (D) from the heat exchange portion (7) measured in an
offset direction (12) perpendicular to both the extension and the
transverse direction (8, 10), wherein the bent portion (11) has a
first end region (13) facing the heat exchange portion (7) with a
first bend (14) counter to the offset direction (12), and a second
end region (15) facing the angled portion (9) with a second bend
(16) in the offset direction (12).
2. The flat tube (1) according to claim 1, wherein the second bend
(16) is a twist-bend (18).
3. The flat tube (1) according to claim 1, wherein the extension
direction (8) follows a straight line.
4. The flat tube (1) according to claim 1, wherein the transverse
direction (10) is perpendicular to the extension direction (8).
5. The flat tube (1) according to claim 1, wherein the distance (D)
at which the angled portion (9) is arranged opposite the heat
exchange portion (7) is smaller than a minimum bending radius (R)
of the second bend (16).
6. The flat tube (1) according to claim 5, wherein the minimum
bending radius (R) of the second bend (16) is 3 to 6 times the tube
thickness (T).
7. The flat tube (1) according to claim 1, wherein the tube body
(2) delimits numerous coolant channels (3) arranged in a queue
along the width (W) of the tube (1), wherein directly adjacent
coolant channels (3) are separated by a division wall (17)
extending along the thickness (T) of the tube body (2).
8. The flat tube (1) according to claim 1, wherein the tube body
(2) comprises a uniform metal material.
9. The flat tube (1) according to claim 1, wherein the bent portion
(11) in a view perpendicular both to the extension and to the
offset direction (8, 12) has an S- or Z-like geometry (19).
10. A heat exchanger (30), comprising: a first collector (36), a
second collector (37), and a third collector (38); first flat tubes
(1), each of which has a tube body (2) delimiting at least one
coolant channel (3) for a coolant or a refrigerant, the tube body
(2) having an outer top surface (4) and an outer bottom surface (5)
arranged opposite one another at a thickness (T) of the tube body
(2) and having two outer side surfaces (6) arranged opposite one
another at a width (W) of the tube body (2), the outer side
surfaces (6) connecting the outer top to the outer bottom (4, 5)
surface, wherein the tube body (2) has a heat exchange portion (7)
extending along an extension direction (8), wherein the tube body
(2) has an angled portion (9) extending along an transverse
direction (10) that is inclined with respect to the extension
direction (8), wherein the tube body (2) has a bent portion (11)
connecting the heat exchange portion (7) to the angled portion (9),
wherein the angled portion (9) is arranged at a distance (D) from
the heat exchange portion (7) measured in an offset direction (12)
perpendicular to both the extension and the transverse direction
(8, 10), wherein the bent portion (11) has a first end region (13)
facing the heat exchange portion (7) with a first bend (14) counter
to the offset direction (12), and a second end region (15) facing
the angled portion (9) with a second bend (16) in the offset
direction (12), wherein first longitudinal ends (20) of the heat
exchange portions (7) facing away from the bent portions (11) are
received in associated first openings (39) of the first collector
(36) and second longitudinal ends (21) of the angled portions (9)
facing away from the bent portions (11) are received in associated
second openings (40) of the second collector (37); second flat
tubes (31), wherein first longitudinal ends (32) of the second flat
tubes (31) are received in associated third openings (41) of the
third collector (38) and second longitudinal ends (33) of the
second flat tubes (31), which are arranged opposite the first
longitudinal ends (32), are received in associated fourth openings
(42) of the first collector (36); wherein the first and fourth
openings (39, 42) are arranged spaced apart from one another.
11. The heat exchanger (30) according to claim 10, wherein the
first flat tubes (1) and the second flat tubes (31) are arranged
alternatingly along a stacking direction that corresponds to the
offset direction (12) of the first flat tubes (1).
12. The heat exchanger (30) according to claim 11, wherein in a
view along the stacking direction, the heat exchange portions (7)
of the first flat tubes (1) completely overlap the second flat
tubes (31), whereas the angled portions (9) of the first flat tubes
(1) do not.
13. The heat exchanger (30) according to claim 10, wherein between
adjacent flat tubes (1, 31) an intermediate space (35) is present,
in which heat transfer fins (34) are accommodated.
14. The heat exchanger (30) according to claim 10, wherein the
second flat tubes (31) are straight.
15. The heat exchanger (30) according to claim 10, wherein each of
the second flat tubes (31) has a tube body (2) delimiting at least
one coolant channel (3) for a coolant or a refrigerant, the tube
body having an outer top surface (4) and an outer bottom surface
(5) arranged opposite one another at a thickness (T) of the tube
body (2) and having two outer side surfaces (6) arranged opposite
one another at a width (W) of the tube body (2), the outer side
surfaces (6) connecting the outer top to the outer bottom (4, 5)
surface, wherein the tube body (2) has a heat exchange portion (7)
extending along an extension direction (8), wherein the tube body
(2) has an angled portion (9) extending along an transverse
direction (10) that is inclined with respect to the extension
direction (8), wherein the tube body (2) has a bent portion (11)
connecting the heat exchange portion (7) to the angled portion (9),
wherein the angled portion (9) is arranged at a distance (D) from
the heat exchange portion (7) measured in an offset direction (12)
perpendicular to both the extension and the transverse direction
(8, 10), wherein the bent portion (11) has a first end region (13)
facing the heat exchange portion (7) with a first bend (14) counter
to the offset direction (12), and a second end region (15) facing
the angled portion (9) with a second bend (16) in the offset
direction (12), wherein the transverse direction (10) of the first
flat tubes (1) differs from the transverse direction of the second
flat tubes (31).
Description
TECHNICAL FIELD
[0001] The invention relates to a flat tube for a heat exchanger as
well as to a heat exchanger having such flat tubes.
BACKGROUND
[0002] In heat pump applications and heat exchangers having
exclusively one single passage it is a problem that under
unfavorable environment conditions the single passage may freeze up
easily. This problem could be solved in that, for example, a
refrigerant pressure drop in a heat exchanger block having flat
tubes is increased, e.g. by an increased deflection of the
refrigerant in the heat exchanger block. An increase of the
pressure drop goes hand in hand with increasing a boiling
temperature of the refrigerant as a result of which the temperature
of the flat tubes or of the heat exchanger block can be increased
and thus the risk of a freezing can be at least reduced. This can
be achieved for example by a meander-like or multi-loop flow
through the heat exchanger.
[0003] From CN 103 644 685 A, a heat exchanger having two inflow
collectors and two outflow collectors is known. This heat exchanger
has two types of flat tubes stacked upon one another alternatingly.
The flat tubes of a second type are substantially straight. The
flat tubes of first type have a sharp bend or fold near their
longitudinal ends, in which bend or fold a central heat exchange
portion of the respective flat tubes merges into an angled portion
of these flat tubes. Accordingly, a first of the inflow and a first
of the outflow collectors are arranged in line with flat tubes of
the second type and a second of the inflow and a second of the
outflow collectors are each arranged aside of the flat tubes of the
second type and connected to the angled portions of the flat tubes
of the first type.
[0004] However, the sharp bend or fold near the longitudinal ends
of the flat tubes (of the first type) leads to increased internal
mechanical stresses in the area of the sharp bend or fold. Thus,
such usual flat tubes may be prone to material failure either
during their manufacturing or whilst operation of the heat
exchanger due to the coolant or refrigerant pressure they have to
withstand when the heat exchanger is operated.
SUMMARY
[0005] The present disclosure presents new ways for the development
of flat tubes for heat exchangers.
[0006] A general idea of the invention therefore is to configure
the bent portion of the flat tube for a heat exchanger as to have a
first and a second bend, via which a heat exchange portion of the
flat tube merges into an angled portion of the flat tube.
[0007] Advantageously, this results in an increased bending radius
opposite that of usual bent flat tubes and thus allows for improved
strength of the flat tube and less likely failure during its
manufacturing or operation.
[0008] The invention concerns a flat tube for a heat exchanger,
having a tube body delimiting at least one coolant channel through
which a coolant or a refrigerant can flow. The tube body has an
outer top and an outer bottom surface arranged opposite one another
at a thickness of the tube body as well as two outer side surfaces
arranged opposite one another at a width of the tube body, the
outer side surfaces connecting the outer top to the outer bottom
surface. It goes without saying that the expressions "outer top
surface" and "outer bottom surface" only refer to a preferred
orientation of the flat tube, wherein this orientation can be
deviated from without leaving the scope of the invention. Thus, if
practical, the flat tube in its operation position can be
orientated as to have its outer bottom surface facing upwards or
downwards or sideways with respect to gravity. The tube body has a
heat exchange portion substantially extending along an extension
direction. The tube body has an angled portion substantially
extending along a transverse direction that is inclined with
respect to the extension direction. Preferably, the first bend has
an S- or Z-like shape comprising two sub-bends, one of which is
directed against and one of which is directed in the offset
direction, wherein both sub bends together cause the tube body to
withdraw counter to the offset direction whilst distancing from the
heat exchange portion in the extension direction. The tube body
also has a bent portion connecting the heat exchange portion to the
angled portion. The angled portion is arranged at a distance from
the heat exchange portion measured in an offset direction
substantially perpendicular to both the extension and the
transverse direction. The bent portion in its first end region
facing the heat exchange portion has a first bend counter to the
offset direction. In its second end region facing the angled
portion, the bent portion has a second bend in the offset
direction. This allows for a particular big bending radius of the
bent portion, such that the mechanical strength of the flat tube
can be enhanced and its manufacturing can be simplified.
[0009] According to a preferred embodiment of the flat tube, the
second bend is a twist-bend. By that, both the inclination of the
angled portion opposite the heat exchange portion and the distance
between the angled portion and the heat exchange portion along the
offset direction can be achieved in a single and thus inexpensive
deformation process.
[0010] According to another preferred embodiment of the flat tube,
the extension direction substantially follows a straight line. This
allows for particular effective heat exchange.
[0011] In another preferred embodiment of the flat tube, the
transverse direction is substantially perpendicular to the
extension direction. Such a flat tube is particularly
cost-effective to produce.
[0012] In another preferred embodiment of the flat tube, the
distance at which the angled portion is arranged opposite the heat
exchange portion is smaller than a minimum bending radius of the
second bend. This way, a mechanical load when bending the flat tube
to its final shape whilst manufacturing can be kept below a failure
load.
[0013] According to another preferred embodiment of the flat tube,
the minimum bending radius of the second bend is 3 to 6 times the
tube thickness. This ratio of the bending radius of the second bend
to the tube thickness has proven to be particularly suitable. In
addition or as an alternative, the minimum bending radius of the
second bend is 0.70 to 0.95 times the tube width. In addition or as
an alternative, heat transfer fins can be present at the outer top
and/or bottom surface, wherein the heat fins protrude from the
respective outer top and/or bottom surface along a fin height,
which fin height is measured perpendicularly opposite the
respective outer top and/or bottom surface, the minimum bending
radius of the second bend being 0.70 to 0.95 times the fin
height.
[0014] According to another preferred embodiment of the flat tube,
the tube body delimits numerous coolant channels arranged in a
queue along the width of the tube, wherein between directly
adjacent coolant channels a division wall extending along the
thickness of the tube body is present. Such a flat tube allows for
particularly even heat exchange distribution at its outer upper and
bottom surfaces. Furthermore, such flat tubes can have a
particularly small thickness.
[0015] In another preferred embodiment of the flat tube, the tube
body has a uniform material or consists of a uniform material,
which material preferably is a metal. This enhances the heat
transfer/exchange and allows bending a semi-finished straight flat
tube as to match the geometry of the flat tube according to this
embodiment of the invention.
[0016] According to another preferred embodiment of the flat tube,
the bent portion in a view perpendicular both to the extension and
to the offset direction has an S- or Z-like geometry. This means
that if the first bend comprises two sub-bends, which together form
an S- or Z-like shape, the second bend steadily adds to the S- or
Z-like shape as to form the S- or Z-like geometry of the bent
portion. By that, the bending radius of the second bend can be
increased.
[0017] The invention also relates to a heat exchanger, which has
first flat tubes, which accord to the invention as described above,
wherein longitudinal ends of their angled portions facing away from
their bent portions are received in associated second openings of a
second collector. Thus, the afore-mentioned advantages of the flat
tube according to the invention transfer to the heat exchanger,
accordingly. Furthermore, the heat exchanger has second flat tubes,
wherein first longitudinal ends of these second flat tubes are
received in associated third openings of a third collector and
second longitudinal ends of the second flat tubes, which are
arranged opposite their first longitudinal ends, are received in
associated fourth openings of the first collector. The first and
fourth openings are arranged spaced apart from one another.
[0018] According to a preferred embodiment of the heat exchanger,
the first flat tubes and the second flat tubes are arranged
alternatingly along a stacking direction that corresponds to, in
particular equals, the offset direction of the first flat tubes. By
the alternating arrangement of the individual flat tubes a
defrosting capacity can be increased. Thereby, a defrosting cycle
can be shortened and the overall energy efficiency of the heat
exchanger can be increased.
[0019] In another preferred embodiment of the heat exchanger, an
intermediate space is present between adjacent flat tubes, in which
heat transfer fins are accommodated. This enhances the heat
exchange/transfer between a fluid led through the intermediate
space and the coolant or refrigerant flowing through the flat
tubes, since the heat transfer fins effectively increase a heat
exchange surface area of the heat exchanger.
[0020] Preferably, whilst assembling the heat exchanger, the heat
transfer fins are held in place by the first bend.
[0021] According to another preferred embodiment of the heat
exchanger, in a view along the stacking direction the heat exchange
portions of the first flat tubes completely overlap the second flat
tubes, whereas the angled portions of the first flat tubes do not.
This allows for particularly well heat exchange whilst keeping a
profile of the heat exchanger and an air pressure drop low.
[0022] In another preferred embodiment of the heat exchanger, the
second flat tubes are substantially straight. Such second flat
tubes can easily be taken from stock without any manufacturing or
modification process on them to be carried out but cutting to
length.
[0023] According to another preferred embodiment of the heat
exchanger, the second flat tubes as well as the first flat tubes
accord to the invention as described above. Then, the transverse
direction of the first flat tubes differs from that of the second
flat tubes. Such a heat exchanger can be set up in a particular
compact design.
[0024] Further important features and advantages of the invention
become evident from the drawings and from the associated detailed
description by way of the drawings.
[0025] It is to be understood that the features mentioned above and
still to be explained in the following cannot only be used in the
respective combination stated but also in other combinations or by
themselves without leaving the scope of the present invention.
[0026] Preferred exemplary embodiments of the invention are shown
in the drawings and are explained in more detail in the following
description, wherein same reference numbers relate to same or
similar or functionally same components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] It shows, in each case schematically:
[0028] FIG. 1A shows an example of a flat tube according to the
invention in a view against a transverse direction;
[0029] FIG. 1B shows the example of FIG. 1A in a view along an
offset direction;
[0030] FIG. 2A shows another example of the flat tube according to
the invention in a view along the offset direction;
[0031] FIG. 2B shows the example of FIG. 2A in a view opposite the
transverse direction;
[0032] FIG. 3A shows, partially, an example of a heat exchanger
according to the invention in a view against the transverse
direction;
[0033] FIG. 3B shows a first flat tube of the heat exchanger of
FIG. 3A in a view along the offset direction;
[0034] FIG. 4A shows the heat exchanger of FIG. 3A in a plan view
along the offset direction; and
[0035] FIG. 4B shows another example of the heat exchanger
according to the invention in a plan view along the offset
direction.
DETAILED DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1A shows an example of a flat tube 1 according to the
invention in a view against a transverse direction 10, which flat
tube 1 is configured to be implemented in a heat exchanger 30
according to the invention, the latter being depicted in FIGS. 3A,
4A and 4B and described later on. FIG. 1B shows the example of FIG.
1A in a view along an offset direction 12. As to be seen from FIGS.
1A and 1B, the flat tube 1 has a tube body 2, which delimits at
least one coolant channel 3 through which a coolant or a
refrigerant can flow. In the example of FIG. 1A, the tube body 2
delimits numerous coolant channels 3, which are arranged in a queue
along the width W of the tube 1. A division wall 17 extending along
the thickness T of the tube body 2 is present between two directly
adjacent coolant channels 3. For example, tube body 2 has a uniform
material or consists of such a uniform material. The material of
the tube body 2 for instance is a metal.
[0037] FIG. 2A illustrates another example of the flat tube 1
according to the invention in a view along the offset direction 12.
FIG. 2B shows the example of FIG. 2A in a view against the
transverse direction 10. In other words, the perspective of FIG. 2A
corresponds to that of FIG. 1B, whereas the perspective of FIG. 2B
is similar to that of FIG. 1A. For the sake of clarity and better
understanding, the coolant channels 3 of the tube body 2 are not
shown in the example of FIGS. 2A and 2B.
[0038] As to be seen from FIGS. 1A, 1B, 2A and 2B, the tube body 2
has an outer top surface 4 and an outer bottom surface 5, which are
arranged opposite one another at a thickness T of the tube body 2.
Tube body 2 also has two outer side surfaces 6, which are arranged
opposite one another at a width W of the tube body 2. The outer
side surfaces 6 connect the outer top and the outer bottom surface
4, 5. Tube body 2 has a heat exchange portion 7, which
substantially extends along an extension direction 8. Tube body 2
has an angled portion 9, which substantially extends along a
transverse direction 10 that is inclined with respect to the
extension direction 8. Tube body 2 has a bent portion 11, which
connects the heat exchange portion 7 to the angled portion 9.
[0039] It is to be seen from FIGS. 1A and 2B, that the angled
portion 9 is arranged at a distance D from the heat exchange
portion 7, which distance D is to be measured in the offset
direction 12. The offset direction 12 is substantially
perpendicular to both the extension and the transverse direction 8,
10. The bent portion 11 has a first bend 14, which is present in a
first end region 13 of the bent portion 11 that faces the heat
exchange portion 7. The first bend 14 of the bent portion 11 is
bent counter to the offset direction 12. Furthermore, the bent
portion 11 has a second bend 16, which is present in a second end
region 15 that faces the angled portion 9. The second bend 16 is
bent in the offset direction 12. In other words, in the first end
region 13 the tube body 2 is set back opposite the heat exchange
portion 7 counter to the offset direction 12 due to the first bend
14. Accordingly, in the second end region 15 the tube body 2 is
protruding from the heat exchange portion 7 and from the first end
region 13 in the offset direction 12 due to the second bend 16. The
bent portion 11, for example, has an S- or Z-like geometry 19.
Between the first bend 14 and the second bend 16 a step bend 22
(see FIGS. 2A and 2B) can be present. The first bend 14 can have an
S- or Z-like shape consisting of two sub-bends, one of which is
directed against and one of which is directed in the offset
direction, wherein both sub bends together cause the tube body 2 to
withdraw counter to the offset direction 12 whilst distancing from
the heat exchange portion 7 in the extension direction 8. When the
first bend 14 comprises of two sub-bends, which both together have
the S- or Z-like shape, the second bend 16 may steadily add to the
S- or Z-like geometry as to form the S- or Z-like geometry 19 of
the bent portion 11.
[0040] Additionally, FIGS. 1A, 1B, 2A and 2B show that the
extension direction 8 substantially follows a straight line. The
transverse direction 10 in the examples of FIGS. 1A, 1B, 2A and 2B
is substantially perpendicular to the extension direction 8. It
goes without saying that as an alternative the transverse direction
10 in contrast to the right angle of FIGS. 1A, 1B, 2A and 2B may be
inclined by a different angle opposite the extension direction 8.
The transverse direction 10 can follow a straight or a curved line.
The distance D at which the angled portion 9 is arranged opposite
the heat exchange portion 7 is smaller than a minimum bending
radius R of the second bend 16. The minimum bending radius R of the
second bend 16 for example is 3 to 6 times the tube thickness T of
the tube body 2. The minimum bending radius R can be 0.70 to 0.95
times the tube width W. The minimum bending Radius R can be
determined by an inner height H of the bent portion 11, which is
measured along the offset direction 12. When progressively
distancing from the heat exchange portion 7, the bent portion 11
firstly is set back counter to the offset direction 12 by the first
bend 14, then the bent portion 11 by its second bend 16 begins
rising in the offset direction 12 as to cross a plane containing
the heat exchange portion 7 and lastly transfer into the angled
portion 9 in the offset direction 10.
[0041] According to FIGS. 1A, 1B, 2A and 2B, the second bend 16 is
a twist-bend 18. This means that in the second bend 16 the tube
body 2 is bent and twisted at the same time, such that on the one
hand the distance D between the angled portion 9 and the heat
exchange portion 7 is bridged and on the other hand the exact same
surface area of the tube body 2, which in the heat exchange portion
7 represents the top surface 4, mutates to the bottom surface 5 in
the area of angled portion 9. Thus, the tube body 2 can be twisted
180.degree. in the second bend 16.
[0042] As mentioned above, the flat tube 1 may be used in a heat
exchanger 30 according to the invention. In FIG. 3A an example of
the heat exchanger 30 according to the invention is partially
depicted in a view against the transverse direction 10. The heat
exchanger 30 has first flat tubes 1 according to the invention, one
of which is illustrated separately in FIG. 3B in a view along the
offset direction 12. Alternatively, the first flat tubes 1 of the
heat exchanger 30 may accord to the examples of FIGS. 1A, 1B, 2A
and 2B as described above. The first flat tubes 1 of the heat
exchanger 30 each have a first longitudinal end 20 of their heat
exchange portions 7, which faces away from their bent portions
11.
[0043] FIG. 4A shows the heat exchanger 30 in a plan view along the
offset direction 12. As to be seen from FIGS. 3A and 4A, the first
longitudinal ends 20 of the first flat tubes 1 are received in
associated first openings 39 of a first collector 36 of the heat
exchanger 30. Each of the first flat tubes 1 also has a second
longitudinal end 21 of their angled portions 9, which faces away
from their bent portion 11. These second longitudinal ends 21 are
received in associated second openings 40 of a second collector 37
of the heat exchanger 30. The heat exchanger 30 furthermore has
second flat tubes 31. These second flat tubes 31 have first
longitudinal ends 32, which are received in associated third
openings 41 of a third collector 38 of the heat exchanger 30. The
second flat tubes 31 also have second longitudinal ends 33, which
are arranged opposite their first longitudinal ends 32, which are
received in associated fourth openings 42 of the first collector 36
of the heat exchanger 30. The first and the fourth openings 39 and
42 are arranged spaced apart from one another.
[0044] As to be seen from FIG. 3A, heat transfer fins 34 can be
present at the outer top and bottom surface 4, 5, wherein the heat
fins 34 protrude from the respective outer top and bottom surface
4, 5 along a fin height HF. The fin height HF is measured
perpendicularly opposite the respective outer top and bottom
surface 4, 5. The minimum bending radius R of the second bend 16 is
0.70 to 0.95 times the fin height HF.
[0045] According to FIGS. 3A and 4A, in the heat exchanger 30, the
first flat tubes 1 and the second flat tubes 31 are arranged
alternatingly along a stacking direction that corresponds to the
offset direction 12 of the first flat tubes 1. For instance, this
stacking direction equals the offset direction 12 of the first flat
tubes 1. Between two adjacent flat tubes 1, 31 an intermediate
space 35 can be present in the heat exchanger 30, in which the heat
transfer fins 34 of the heat exchanger 30 are accommodated. In a
view along the stacking direction the heat exchange portions 7 of
the first flat tubes 1 for example completely overlap the second
flat tubes 31, whereas the angled portions 9 of the first flat
tubes 1 do at least partially not overlap the second flat tubes 31.
For example, the second flat tubes 31 may substantially be
straight. For instance, whilst assembling the heat exchanger 30,
the heat transfer fins 34 can be held in place by the first bends
14 of the first flat tubes 1.
[0046] In an alternative example of the heat exchanger, which
is--in a plan view along the offset direction 12--shown in FIG. 4B
as an example, the second flat tubes 31 are configured to
substantially accord to the flat tube 1 of the invention as
exemplary depicted in FIGS. 1A, 1B, 2A and 2B and described above,
wherein the transverse direction 10 of the first flat tubes 1
differs from the transverse direction 10' of the second flat tubes
31. Thus, both the first and the second flat tubes 1 and 31 in the
heat exchanger 30 may accord to the flat tube 1 according to the
invention, wherein they are mounted in different, in particular
mirrored, orientations in the heat exchanger 30. In the example of
FIG. 4B, the first and the second flat tubes 1 and 31 are formed as
identical parts, that only differ in their orientation in the heat
exchanger 30.
[0047] While the above description constitutes the preferred
embodiments of the present invention, the invention is susceptible
to modification, variation and change without departing from the
proper scope and fair meaning of the accompanying claims.
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