U.S. patent application number 13/577343 was filed with the patent office on 2013-05-16 for heat exchanger.
The applicant listed for this patent is Hiroaki Kondo, Hisashi Segawa, Shouichirou Usui. Invention is credited to Hiroaki Kondo, Hisashi Segawa, Shouichirou Usui.
Application Number | 20130118724 13/577343 |
Document ID | / |
Family ID | 44355142 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130118724 |
Kind Code |
A1 |
Usui; Shouichirou ; et
al. |
May 16, 2013 |
HEAT EXCHANGER
Abstract
A heat exchanger wherein the pipe member is formed in a single
stage to reduce the height of the heat exchanger in the thickness
direction to enable the heat exchanger to be mounted below the
floor of an automobile and wherein the pipe member is prevented
from being broken. The heat exchanger includes: fin members formed
as corrugated fins and having engagement recesses formed in curved
sections; and a pipe member formed by connecting straight pipe
sections by U-shaped bend sections, the straight pipe sections
being arranged by means of the fin members.
Inventors: |
Usui; Shouichirou;
(Sunto-gun, JP) ; Kondo; Hiroaki; (Sunto-gun,
JP) ; Segawa; Hisashi; (Sunto-gun, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Usui; Shouichirou
Kondo; Hiroaki
Segawa; Hisashi |
Sunto-gun
Sunto-gun
Sunto-gun |
|
JP
JP
JP |
|
|
Family ID: |
44355142 |
Appl. No.: |
13/577343 |
Filed: |
October 29, 2010 |
PCT Filed: |
October 29, 2010 |
PCT NO: |
PCT/JP2010/069768 |
371 Date: |
October 12, 2012 |
Current U.S.
Class: |
165/181 |
Current CPC
Class: |
F28F 1/32 20130101; F28D
1/0477 20130101; F28F 1/10 20130101; F28F 2215/12 20130101; F28F
9/002 20130101; F28F 1/126 20130101 |
Class at
Publication: |
165/181 |
International
Class: |
F28F 1/10 20060101
F28F001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2010 |
JP |
2010-022997 |
Claims
1. A heat exchanger comprising: a plurality of fin members formed
as corrugated fins by folding a sheet material into a corrugated
shape, so as to provide curved sections n formed due to the folding
that press-deformed into a recessed shape to form engagement
recesses; and a meanderingly shaped pipe member including a
plurality of straight pipe sections arranged in parallel with the
fin members therebetween, the straight pipe sections being
connected by U-shaped return bends; in which the straight pipe
sections engage with the engagement recesses of the fin members,
and upon such engagement an outer diameter of the pipe member is in
the range of 8 mm to 12 mm, and a facing distance between curved
top sections of the fin members that project farthest outward of
the curved sections of neighbouring fin members is in the range of
0.5 mm to 5.0 mm, and a height of protrusion of the fin members
from a surface of the straight pipe sections is less than or equal
to 11 mm and satisfies, within said range of 0.5 mm to 5.0 mm for
the facing distance, the formula y distance, the formula y>22.46
x.sup.-0.29 in which y is a height of protrusion of the fin members
from the surface of the pipe member/facing distance between the
curved top sections, and x is a facing distance between the curved
top sections.
2. The heat exchanger according to claim 1, wherein a sheet
thickness of the sheet material forming the fin members is in the
range from 0.2 mm to 0.5 mm.
3. The heat exchanger according to claim 1 or 2, wherein a fin
arrangement distance is in the range from 1.6 mm to 2.2 mm.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an air-cooled heat
exchanger chiefly for installation in an automobile under a floor
or in a lower part of an engine compartment thereof, particularly
at the bottom of an engine front end.
[0002] Conventionally, as a heat exchanger for automotive and other
applications, a heat exchanger has been generally known, as shown
in JP-2005-201622A, that is composed of a fin member of corrugated
shape arranged on a meanderingly formed pipe member. This heat
exchanger, while being compact, by the meandering formation of the
pipe member enables making the flow path of the fluid circulating
within the pipe member long, and by using the fin member of
corrugated shape enables a large number of fins to be arranged,
such that an improved heat exchange performance can be
achieved.
SUMMARY OF THE INVENTION
[0003] However, whereas it is necessary to reduce the height in the
thickness direction in particular if a heat exchanger is to be
installed in a narrow space such as under the floor of an
automobile or the lower engine compartment thereof, the height in
the thickness direction of a heat exchanger of the kind shown in
JP-2005-201622A is high, as is shown in FIG. 18 of JP-2005-201622A,
due to the pipe member being formed in two stages. Here, as a
measure to reduce the height in the thickness direction over the
invention disclosed by JP-2005-201622A, it is conceivable to bring
the two-stage pipe member into a single-stage form, at the same
time shortening the formation width of the fin member in the
thickness direction of the heat exchanger. However, if the
formation width of the fin member is made too short, the surface of
the pipe member to which the fin member is attached is exposed to
the outside rather than the fin member. Therefore, a stone flipped
up from the road surface during driving may easily hit the exposed
surface of the pipe member, and in case wherein the flying stone
directly hits the pipe member, it is feared that a situation arises
where the portion of the pipe member that was hit is damaged such
that an indentation is formed, stress concentration due to external
forces from vibration and the like occurs at the indentation, and
the pipe member breaks.
[0004] The present invention attempts to solve the above-mentioned
problem, by meanderingly forming the pipe member into a single
stage to achieve a low height in the thickness direction of the
heat exchanger such that the installability under the floor, in the
lower engine compartment etc. of an automobile is rendered
favourable, at the same time aiming to obtain a heat exchanger that
enables preventing a situation where a stone flipped up from the
road surface during driving damages the pipe member by direct
contact, stress concentration due to external forces from vibration
and the like occurs at the indentation formed by the damage, and
the pipe member breaks.
[0005] The present invention, in order to solve the above-mentioned
problem, comprises a plurality of fin members formed by repeatedly
folding a plate material over itself into a corrugated shape to
form corrugated fins, wherein curved sections that are formed due
to the folding are press-deformed into a recessed shape to form
engagement recesses, and a meanderingly shaped pipe member
including a plurality of straight pipe sections arranged in
parallels with the fin members in-between as well as U-shaped
return bends for the straight pipe sections, wherein the straight
pipe sections of the pipe member are engaged with the engagement
recesses of the fin members. Because, in the invention as given
above, fin members formed with corrugated fins are mounted to a
pipe member of meandering shape that is formed integrally including
multiple straight pipe sections, it is easy to arrange a plurality
of fins on the pipe member, which enables an ability to simplify
manufacturing.
[0006] Because the fin members are formed by corrugated fins, the
presence of curved sections formed between the individual fins of
the corrugated fins furthermore enables the surface area of the fin
members to be made large. Consequently, it becomes possible to
efficiently dissipate heat from the pipe member, thus enabling
improving the heat exchange performance. Furthermore, by adopting
the above structure a single-stage heat exchanger is formed,
different from the two-stage heat exchanger disclosed in
JP-2005-201622A, which enables obtaining low product height in the
thickness direction such that the installability under the floor of
an automobile can be made favourable.
[0007] Also, the outer diameter of the pipe member is set to within
8 mm to 12 mm. If the outer diameter of the pipe member is less
than 8 mm, especially when using oil, gasoline, petroleum
distillate and the like as pipe fluid, situations will arise where
the pressure loss of the fluid becomes large such that a required
flow rate becomes difficult to secure, the flow rate diminishes
such that a desired heat exchange duty becomes difficult to fulfil,
or the pressure loss exceeds a threshold value such that use
becomes impossible. If on the other hand it is greater than 12.0
mm, notwithstanding that along with the enlargement of the outer
diameter the required flow rate becomes easier to secure, the
overall product becomes bulky, leading to a deterioration of the
installability into narrow spaces such as under the floor or in the
lower engine compartment of an automobile.
[0008] Also, a facing distance between curved top sections that
project farthest outward of the curved sections of neighbouring fin
members is set to within 0.5 to 5.0 mm. Within the present
invention a curved top section means, of a curved section in a fin
member that was bendingly formed by the folding of the plate
material, the apex standing out farthest in the folding width
direction of the fin member. In the case of the facing distance
being increased beyond 5.0 mm, the necessity arises to arrange
neighbouring fin members in the direction of separation, with the
pipe member in-between. As a consequence, the engagement recesses
of the fin members will become shallow, as well as narrow in the
axial direction of the pipe member, with a formation length in the
direction perpendicular to the axial direction of the pipe member
moreover being short, and because it is in these shallow,
narrow-width, short-length engagement recesses that the pipe member
is engagingly arranged, the contact area between the fin members
and the pipe member becomes small such that, together with a
decline in heat exchange performance, a worsening of the mounting
strength may occur.
[0009] On the other hand, in case of the facing distance being set
to less than 0.5 mm, the facing distance of neighbouring fin
members becomes narrow such that it becomes difficult for stones
flipped up from the road surface to enter within this facing
distance, such that a situation where a flying stone directly hits
the surface of the pipe member during driving becomes unlikely to
occur, which is favourable in regard to preventing situations where
the pipe member is damaged at its surface by a flying stone forming
an indentation, develops stress concentrations due to external
forces from vibrations and the like at the indentation, and breaks.
However, in order to bring the facing distance below 0.5 mm, the
protruding portions of neighbouring fin members have to be arranged
side by side with each other, and since the pipe member is situated
between the neighbouring fins, arranging both protruding portions
side by side demands forming the engagement recesses deeply, in
order to engagingly arrange the pipe member in the deep engagement
recesses. In consequence, large shear forces that rise in
conjunction with the large deformation during the forming of the
deep engagement recesses may cause unneeded deformation to occur in
the vicinity of the engagement recesses. Within the present
invention, facing distance means the arrangement distance of
neighbouring fin members, which face each other having the pipe
member interposed between them, and in particular means the
distance at the curved top sections protruding from the engagement
recesses in the fin member width direction, where the pipe member
interposed between the fin members does not intervene.
[0010] Also, the height of protrusion of the fin members from the
surface of the straight pipe sections of the pipe members is set to
11 mm or less. As for the reason thereof, if the fin members'
height of protrusion in the width direction is increased beyond 11
mm the overall product assembled with the fin members becomes bulky
such that its installability into automobiles etc. is diminished,
while it has become clear from a calculation of the fin efficiency
of the fin members, shown below, that a remarkable improvement of
the heat exchange performance cannot be expected. Here, the
relationship between the height of protrusion of the fin members
and the fin efficiency concerning the heat exchange efficiency of
the fin members will be explained in the following.
[0011] The calculation was performed using the formula
.eta.=tan h(m L)/m L
m.ident.(2h/k.delta..sub.t).sup.1/2.times.L
[0012] .eta.: fin efficiency (%)
[0013] k: thermal conductivity (ca. 150 W/mK for a standard
aluminium alloy)
[0014] h: heat transfer coefficient (ca. 60 W/m.sup.2K
perpendicular to the bending plane, ca.
[0015] 25 W/m.sup.2K parallel to the bending plane)
[0016] L: height of protrusion of the fin members (mm)
[0017] .delta..sub.t: sheet thickness of the fin members (0.3
mm)
wherein for the purpose of simplifying calculation the heat
exchanger according to the present invention was imaginatively
approximated with planar fins that do not possess curved fold-back
portions. A graph produced on the basis of this calculation is
shown in FIG. 2. While the above fin efficiency means the
efficiency of heat dissipation by the fin members, which changes
according to the fin member shape, the fin member height, and the
fin member sheet thickness, the result in FIG. 2 expresses the
condition of change of the fin efficiency where the fin member
shape, density, and the sheet thickness of the fin members were
held constant, and only the fin member height was varied in the
range from 3 mm to 13.5 mm.
[0018] From FIG. 2, it is evident that if the height of protrusion
of the fin members in the width direction exceeds 11 mm, the fin
efficiency becomes less than 80%, causing the heat exchange
efficiency to diminish, whereas setting the height of protrusion of
the fin members below 11 mm enables the fin efficiency to be
secured at 80% and above, such that the heat exchange efficiency
can be satisfactorily maintained. Accordingly, in order to
satisfactorily maintain the heat exchange efficiency in the present
invention, the height of protrusion of the fin members in the width
direction has to be set to 11 mm or less.
[0019] In the context of limiting as aforesaid the height of
protrusion of the fin members to 11 mm or less, the present
invention sets said height of protrusion of the fin members to a
value that, within said range of 0.5 mm to 5.0 mm for the facing
distance of the curved top sections, satisfies the formula
y.gtoreq.2.46 x.sup.-0.29 (y: height of protrusion of the fin
members in the width direction from the pipe member surface/facing
distance of the curved top sections, x: facing distance of the
curved top sections). This formula has been derived from
experiments and simulation analyses as follows.
[0020] First, in order to decide on a shape for the flying stone to
be used in the simulation analyses, flying stone tests were
performed wherein, together with setting the facing distance t of
the curved top sections of the fin members to 2.0 mm and the sheet
thickness of the fin members to 0.3 mm, the height of protrusion L
in the width direction of the fin members was respectively set to 3
mm and 4 mm. These flying stone tests are tests complying with the
automotive standard JASO M104 "Testing methods for automobile brake
tube" (section: First section, test purpose: Testing method aiming
to cause degradation of the organic coating or other exterior
surface of the brake tube, Test title: Flying stone test (testing
method item No. 5.1)), wherein the testing conditions and testing
apparatus according to the standard are chiefly as follows. [0021]
(1) air pressure: 0.4.+-.0.03 MPa [0022] (2) blast angle:
perpendicular [0023] (3) blast distance: 350 mm [0024] (4) amount
of flying stones: 850 g [0025] (5) repetition: 5 times [0026] (6)
testing apparatus: gravelometer [0027] (7) flying stones: granite
(gravel, size 9 mm to 15 mm)
[0028] Now, whereas the above JASO method standard uses gravel
having a smooth surface for the flying stones, in the present
flying stone tests, in order to cause larger degradation of the
organic coating or other exterior surface to carry out stricter
evaluation testing, abrasive media commercially available as
abrasive media for general cutting (manufactured by Tipton Corp.:
item name "GT", item No. 4) were selected to be used for performing
the evaluation. These abrasive media have edge portions, being
substantially equilateral triangular columns or substantially
equilateral triangular frustrums with a lateral length of about 10
mm and a height of about 8 mm, and are used in practice by some
automobile manufacturers for the above flying-stone tests.
[0029] Results of flying-stone tests using the abrasive media are
shown in FIGS. 3 and 4. Further, FIG. 3(a) is an enlarged plan view
photograph of a heat exchanger before a flying-stone test for a
case where the height of protrusion L in width direction of the fin
members was set to 4 mm, and FIG. 3(b) is an enlarged partial plan
view photograph of the heat exchanger after the flying-stone test
for the case where the height of protrusion L in width direction of
the fin members was set to 4 mm. Likewise, FIG. 4(a) is an enlarged
plan view photograph of a heat exchanger before a flying-stone test
for a case where the height of protrusion L in width direction of
the fin members was set to 3 mm, and FIG. 4(b) is an enlarged
partial plan view photograph of the heat exchanger after the
flying-stone test for the case where the height of protrusion L in
width direction of the fin members was set to 3 mm.
[0030] Then, in the case of the height of protrusion in width
direction of the fin members being 4 mm, as shown in FIG. 3(b),
confirmation by visual inspection of the pipe member surface
resulted in that scars due to flying stones were not confirmed. On
the other hand, in the case where the height of protrusion in width
direction of the fin members had been set to 3 mm, as shown in FIG.
4(b), several scars caused by flying stones were confirmed by
visual inspection. These results made clear that, under the
condition that the facing distance t between the curved top
sections of the fin members is 2.0 mm, in case of setting the
height of protrusion L in width direction of the fin members to 3
mm it becomes easy for flying stones to directly hit the surface of
the pipe member, whereas in case of setting the height of
protrusion L in width direction of the fin members was set 4 mm it
hardly occurs that flying stones directly hit the pipe member
surface.
[0031] In the above flying-stone tests, the testing was performed
for cases where the facing distance t of the curved top sections of
the fin members was 2 mm, whereas for other facing distances,
simulation analyses about the effect of flying stones were
performed according to schematic diagrams based on the
aforementioned results. To explain the simulation analyses, at
first, schematic diagrams as shown in FIG. 5 were drawn up, based
on the above testing results, for the cases where the facing
distance t of the curved top sections of the fin members was 2 mm,
in order to decide on the flying stone shape to be used in the
simulation analyses. Further, each schematic diagram in FIGS. 5 and
6 is a schematic rendition of a cross sectional view of a heat
exchanger, oriented perpendicular to the axial direction of the
straight pipe sections of the pipe member. Further, FIG. 5(a) is a
schematic diagram for the case wherein the height of protrusion L
in width direction of the fin members is 3 mm, and FIG. 5(b) is a
schematic diagram for the case wherein the height of protrusion L
in width direction of the fin members is 4 mm.
[0032] Given the fact that, in the above flying-stone tests, the
surface of the pipe member was directly hit by flying stones in the
case where the height of protrusion in width direction of the fin
members was set to 3 mm, while the pipe member surface was not hit
by flying stones in the case where the height of protrusion in
width direction of the fin members was set to 4 mm, in the
schematic diagrams shown in FIG. 5 the shape of the heat exchanger
(20) was schematically represented such that for the case where the
height of protrusion L in width direction of the fin members was
set to 3 mm (FIG. 5(a)) the flying stone (21) is in a state of
touching the surface of the pipe member (1), and for the case where
the height of protrusion L in width direction of the fin members
was set to 4 mm (FIG. 5(h)) the shortest distance P between the
surface of the pipe member (1) and the flying stone (21) becomes 1
mm.
[0033] From the representation in this way in the schematic
diagrams, the shape of the flying stone in the instant of
contacting the pipe member surface, as shown in FIG. 5, was decided
to be an upturned triangle in the present simulation analyses.
Further, in the present simulation analyses, the limit value for
the shortest distance between the pipe member (1) and the flying
stone (21) in the case wherein the flying stone (21) as shown in
FIG. 5(b) does not directly hit the pipe member (1) is set to 1 mm,
assuming that if in the schematic diagram the distance between the
pipe member and the flying stone is at least 1 mm or more, the pipe
member will also not be directly hit by flying stones during actual
driving.
[0034] Then, in the same way as for the cases shown in FIG. 5
wherein the facing distance t is 2 mm, schematic diagrams as shown
in FIGS. 6(a) to (d) were prepared and simulation analyses
performed for cases wherein the facing distance t is 0.5 mm, 1 mm,
4 mm, and 5 mm, concerning the relationship between each facing
distance t and the height of protrusion L in width direction of the
fin members. Within FIG. 6, schematic diagrams are shown for
respective cases wherein the facing distance t in (a) is 0.5 mm,
the facing distance tin (b) is 1 mm, the facing distance tin (c) is
4 mm, and the facing distance tin (d) is 5 mm. Then, from the
schematic diagrams of FIG. 6, for each of the aforementioned facing
distances t a lower bound for the height of protrusion L of the fin
members was extracted for which the shortest distance between the
flying stone (21) and the surface of the pipe member (1) becomes 1
mm, i.e. which prevents flying stones from directly hitting the
pipe member.
[0035] As a result, as shown in FIGS. 6(a) to (d), the height of
protrusion L in width direction of the fin members (3) for which
the distance between the surface of the pipe member (1) and the
flying stone (21) becomes 1 mm, was 1.7 mm for the case of the
facing distance t being 0.5 mm, 2.5 mm for the case of the facing
distance t being 1 mm, 7.0 mm for the case of the facing distance t
being 4 mm, and 8.5 mm for the case of the facing distance t being
5 mm. Then, the respective heights of protrusion L of the fin
members were taken as lower bounds for the height of protrusion of
the fin members for which, given the respective facing distances,
the surface of the pipe member is not directly hit by flying
stones.
[0036] Next, concerning the results from carrying out the above
simulation analyses, as shown in FIG. 7, the relationship between
the facing distance t of the curved top sections of the fin
members, and height of protrusion L in width direction of the fin
member/facing distance t of the curved top sections of the fin
members, was plotted to be represented as a graph, and from a curve
fitted to the plot the formula y=2.46 x.sup.-0.29 (y: height of
protrusion of the fin members from the surface of the pipe
member/facing distance between the curved top sections, x: facing
distance between the curved top sections) was derived.
[0037] Then, because the higher the height of protrusion in the
width direction of the fin members is made the farther the surface
of the pipe member is positioned towards the interior of the fin
members, it can be said that it becomes difficult for flying stones
to directly hit the surface of the pipe member if the height of
protrusion in width direction of the fin members satisfies the
relationship y.gtoreq.2.46 x.sup.-0.29 (y: height of protrusion of
the fin members from the surface of the pipe member/facing distance
between the curved top sections, x: facing distance between the
curved top sections). On the other hand, if y<2.46 x.sup.-0.29
(y: height of protrusion of the fin members from the surface of the
pipe member/facing distance between the curved top sections, x:
facing distance between the curved top sections) within a range of
0.5 mm to 5.0 for the facing distance of the curved top sections of
the fin members, the height of protrusion in the width direction of
the fin members will become insufficient, such that the distance
from the fin members to the pipe member surface will become small,
causing direct hits by flying stones to easily occur.
[0038] Furthermore, the fin members may also have a sheet thickness
in the range from 0.2 mm to 0.5 mm. If the sheet thickness is set
to less than 0.2 mm, due to the fin members becoming thin the heat
capacity of the fins will become deficient, which accelerates the
temperature fall in the fins such that the heat exchange efficiency
is diminished, while at the same time the fin strength is
diminished such that it becomes easy for flying stones to come into
contact with the surface of the pipe member. Also, if it is made
thicker than 0.5 mm, notwithstanding that the strength is raised,
material is wasted since with regarding the heat exchange
efficiency, while being slightly improved, a remarkable rise cannot
be expected.
[0039] Also, the fin members may have an arrangement distance of
the fins, which are formed by a folding process, in the range from
1.6 mm to 2.2 mm. The fin arrangement distance means, within the
plurality of fin portions formed by the folding process in the fin
member, the separation distance between neighbouring individual
fins in the pipe axis direction of the straight pipe sections of
the pipe member. The numerical range of the fin arrangement
distance from 1.6 mm to 2.2 mm is based on the cooling performance
test result given below. To explain the cooling performance test,
at first, by using fin members comprising an aluminium-alloy fin
member sheet thickness of 0.3 mm, among the mechanical properties a
tensile strength of 200 MPa, and fin arrangement distances of 1.6
mm, 2.0 mm, 2.3 mm, 3.2 mm, and 4.0 mm, respectively, heat
exchangers for each of the respective arrangement distances were
produced.
[0040] Then, the respective heat exchangers comprising the
different fin arrangement distances were installed in a tubular
wind tunnel of rectangular cross section, such as to become
parallel to the wind direction (not in the typical way of
installing heat exchangers, which is perpendicular) as received
when installed in a car, water was passed through the pipe members
of the heat exchangers, and the temperature of the water flowing
into the heat exchanger as well as the temperature of the water
having passed the heat exchanger were each measured. The
measurement conditions at the time were as follows.
TABLE-US-00001 water inlet temperature 70.degree. C. constant air
stream inlet temperature 20.degree. C. constant in-pipe water flow
rate 1.5 . . . 2.5 L/min air stream velocity 2.5 . . . 5.5 m/s
[0041] Then, for each heat exchanger measured at the above
measurement conditions, in addition to the inlet temperatures and
the outlet temperatures of the water as the pipe fluid and of the
air as the fluid between the fins, the respective temperature
differences for both temperatures were calculated, the temperature
differences were converted into a temperature difference for the
case of using light oil instead of water, and the converted
temperature differences were taken as the temperature drop of the
fluids upon passing the heat exchanger according to the present
invention. It should be noted that the conditions when converted
were as follows.
TABLE-US-00002 light oil inlet temperature 100.degree. C. air
stream inlet temperature 50.degree. C. light oil flow rate 0.75
L/min air stream velocity 5 m/s
[0042] Then, the relationship between the temperature drop of the
pipe fluid thus obtained for each heat exchanger and the fin
arrangement distance of the respective heat exchanger were plotted
to be represented in a graph as shown in FIG. 8. It becomes clear
from FIG. 8 that within the range from 1.6 mm to 2.2 mm for the
arrangement distance, the temperature drop of the pipe fluid
exceeds about 10.degree. C. From this result, because the
temperature drop of the pipe fluid due to passing the heat
exchanger exhibits high values for fin arrangement distances within
the range from 1.6 mm to 2.2 mm compared to other fin arrangement
distances, it is preferred to set the fin arrangement distance to
the range from 1.6 mm to 2.2 mm in order to maintain a good heat
exchange performance. And, if the fin arrangement distance is less
than 1.6 mm, while the surface area of the fin members is enlarged,
the heat exchange performance is reduced because the arrangement
distance becomes too narrow such that the flow regime of the fluid
becomes worse due to increases flow restriction, whereas if the
arrangement distance is wider than 2.2 mm, while the flow is eased
due to diminished flow restriction, the heat exchange performance
is reduced also in this case because the surface area of the fin
member becomes smaller.
EFFECT OF THE INVENTION
[0043] Because the present invention is configured as stated above,
comprising fin members formed as corrugated fins engagingly
arranged on a meanderingly formed pipe member, manufacturing is
enabled to be made simple, while at the same time it becomes
possible to make the surface area of the fin members large, thereby
enabling to dissipate efficiently the heat from the pipe member. In
addition, forming a heat exchanger according to the configuration
and within the dimensional ranges as stated above enables, without
compromising the good heat exchange performance, to eliminate the
danger that during driving a stone flipped up from the road surface
directly hits the surface of the pipe member, thereby damaging the
portion of the pipe member that was hit such that an indentation is
formed, stress concentration due to external forces from vibration
and the like occurs at the indentation, and the pipe member breaks,
while furthermore the height of the product in the thickness
direction can be made low. For this reason, it becomes possible to
achieve a favourable installability into a narrow space such as
under the floor of an automobile or the lower engine compartment
thereof, particularly at the bottom of an engine front end or the
like.
BRIEF EXPLANATION OF THE DRAWINGS
[0044] FIG. 1 is a perspective view showing Embodiment 1 of the
present invention.
[0045] FIG. 2 is a graph showing the relationship between the
height of protrusion in width direction of the fin member and fin
efficiency.
[0046] FIG. 3(a) is an enlarged partial plan view photograph
showing the state of a heat exchanger before a flying-stone
experiment wherein the height of protrusion in width direction of
the fin member was set to 4 mm. FIG. 3(b) is an enlarged partial
plan view photograph showing the state of the heat exchanger after
the flying-stone experiment wherein the height of protrusion in
width direction of the fin member was set to 4 mm.
[0047] FIG. 4(a) is an enlarged partial plan view photograph
showing the state of a heat exchanger before a flying-stone
experiment wherein the height of protrusion in width direction of
the fin member was set to 3 mm. FIG. 4(b) is an enlarged partial
plan view photograph showing the state of the heat exchanger after
the flying-stone experiment wherein the height of protrusion in
width direction of the fin member was set to 3 mm.
[0048] FIGS. 5(a) to 5(b) are schematic diagrams used for a
simulation analysis of a facing distance t =2 between the curved
top sections of the fin members.
[0049] FIGS. 6(a) to 6(d) are schematic diagrams used for
simulation analyses of a respective facing distance of t=0.5, 1, 4,
5 between the curved top sections of the fin members.
[0050] FIG. 7 is a graph reflecting the relationship between the
facing distance of the curved top sections of the fin members, and
height of protrusion in width direction of the fin member/facing
distance of the curved top sections of the fin members, with a
curve fitted thereto.
[0051] FIG. 8 is a graph reflecting the relationship between the
fin arrangement distance and the temperature drop of the pipe fluid
passing through the heat exchanger.
[0052] FIG. 9 is a perspective view showing the fin member of
Embodiment 1.
[0053] FIG. 10 is an enlarged partial cross-sectional view along
line A-A in FIG. 1.
[0054] FIG. 11 is an enlarged partial cross-sectional view along
line B-B in FIG. 1.
EMBODIMENT 1
[0055] To explain Embodiment 1 of the invention, (1) is a pipe
member formed of an aluminium alloy, as shown in FIG. 1, wherein a
plurality of straight pipe sections (2) is arranged in parallels
separated by a fin-member (3) insertion gap (4), ends of the
straight pipe sections (2) being curvedly formed such that the
curved portions provide U-shaped return bends (5). Through forming
the pipe member (1) in this way in meandering fashion, the
fin-member (3) insertion gap (4) is formed to line up in preferably
multiple instances. Within each insertion gap (4), a respective fin
member (3) is engagingly arranged. Furthermore, in the present
embodiment, the outer diameter r of the pipe member (1) indicated
in FIG. 11 is set to 8 mm. Also, although in the present
embodiment, as stated above, the pipe member (1) is formed of an
aluminium alloy, in different embodiments it is also possible to
form the pipe member (1) from steel, stainless steel, copper, a
copper alloy, titanium, a titanium alloy or the like.
[0056] The above-mentioned fin members (3) are formed from an
aluminium alloy strip material in flat-sheet form having a sheet
thickness of 0.3 mm, through bending the strip material as shown in
FIG. 9 into a corrugated shape of uniform folding-wave height as
corrugated fins. By providing the fin members (3) in this way as
corrugated fins, a large number of fins (7) of flat-board shape,
connected by curved sections (6) formed due to the folding process,
are integrally formed. Furthermore, in the present embodiment an
arrangement distance (18) q of the fins (7), shown in FIG. 10, is
set to 2.0 mm. Accordingly, the forming of the fin members (3) as
stated above facilitates to arrange a large number of fins (7) in
evenly spaced and parallel fashion on the pipe member (1), while
the large number of fins (7) and the large number of curved
sections (6) enable to make the surface area of the fin members (3)
large, such that a product with high heat exchange performance can
easily be produced. Also, due to the presence of the curved
sections (6) the fin members (3) become three-dimensional,
providing an integral structure that is structurally stable, such
that the shock resistance improves, and an improvement also of the
durability of the heat exchanger (20) is enabled. Furthermore,
although in the present embodiment the fin members (3) are formed
of an aluminium alloy, in different embodiments it is also possible
to form the same from steel, stainless steel, copper, a copper
alloy, titanium, a titanium alloy or the like.
[0057] In the fin members (3) formed as stated above, by
press-forming curved top sections (15), which of the curvedly
formed curved sections (6) project farthest outward, into a
recessed shape, arc-shaped engagement recesses (8) as shown in FIG.
9 are formed. As shown in FIGS. 10 and 11, in order to enable
surface contact with the outer periphery (10) of the pipe member
(1), the shape of the engagement recesses (8) is made to correspond
to the outer periphery (10) of the pipe member (1).
[0058] Then, in a state where the pipe member (1) is engaged to the
engagement recesses (8), as shown in FIG. 1, the fin members (3)
are insertingly arranged into the respective insertion gaps (4)
with the pipe member (1) on either side. Then, after arranging the
fin members (3) as described, both ends and both sides of the pipe
member (1), as shown in FIG. 1, are covered respectively by pairs
of end cover members (11) and side cover members (12), with both
end sections (13) of the pipe member (1) arranged protruding from
one of the end cover members (11). Besides, on both sides of the
end cover members (11) brackets (14) for mounting the heat
exchanger (20) of the present embodiment under a vehicle floor etc.
are protrudingly formed.
[0059] The heat exchanger (20) of the present embodiment as stated
above, due to comprising a simple configuration wherein fin members
(3) that are corrugated fins are engagingly arranged on a pipe
member (1), enables to make manufacturing simple, while due to the
large surface area of the fin members (3) it becomes possible to
dissipate efficiently heat from the pipe member (1), thereby
enabling to easily raise the heat exchange performance. Also, as
shown in FIG. 1, due to a configuration wherein the fin members (3)
are arranged in a row within a single stage, different from the
two-stage heat exchanger disclosed in JP-2005-201622A, the height
of the heat exchanger (20) in the thickness direction can be made
low. This enables the installability into narrow spaces such as
under a floor of an automobile to be made favourable.
[0060] Also, since the arrangement distance (18) q of the fins (7)
is set to 2.0 mm, it becomes possible, as shown in FIG. 8, to make
the temperature drop of the pipe fluid upon passing the heat
exchanger (20) high in comparison to other arrangement distances,
thereby enabling to obtain a heat exchanger (20) with excellent
heat exchange performance. Also, the facing distance (17) t of the
curved top sections (15) in neighbouring fin members' (3)
protruding portions (16) from the pipe member (1) surface is set to
2 mm. Furthermore, the height of protrusion L from the pipe member
(1) surface in width direction of the fin members (3), shown in
FIG. 10, is 4 mm, and in relation to the facing distance (17) t=2
mm of the curved top sections (15) the formula y.gtoreq.2.46
x.sup.-0.29 (y: height of protrusion L in width direction of the
fin members (3) from the surface of the pipe member (1)/facing
distance (17) t between the curved top sections (15), x: facing
distance (17) t between the curved top sections (15)) is
satisfied.
[0061] On the heat exchanger (20) of the present embodiment,
prepared as explained above, a flying stone test was performed. The
test was carried out according to automotive standard JASO M104
"Testing methods for automobile brake tube", which simulates that
during running of an automobile a stone on the road surface is
flipped up by a wheel, comes flying and touches. The testing
conditions for the flying stone testing on the present embodiment
were as follows. [0062] (1) air pressure: 0.4.+-.0.03 MPa [0063]
(2) blast angle: perpendicular [0064] (3) blast distance: 350 mm
[0065] (4) amount of flying stones: 850 g [0066] (5) repetition: 5
times [0067] (6) testing apparatus: gravelometer (manufactured by
Suga Test Instruments Co. Ltd., flying stone testing apparatus
JA400) [0068] (7) flying stones: item name "GT", item No. 4
(manufactured by Tipton Corp.: abrasive media having edge portions,
for use in cutting, of substantially equilateral triangular column
shape or substantially equilateral triangular frustrum shape, with
a lateral length of about 10 mm and a height of about 8 mm)
[0069] Then, the surface condition of the fin members (3) and the
pipe member (1) after carrying out the flying stone test was
visually inspected. The surface condition of the fin members (3)
and the pipe member (1) after carrying out the flying stone test is
shown in the photographs of FIG. 3. From FIG. 3(b), it could be
confirmed, from the fact the individual fins (7) were in contorted
condition due to direct impact of flying stones, that the fin
members (3) had undergone heavy damage. However, on the surface of
the pipe member (1), almost no scars thought to have originated
from contact by flying stones could be confirmed. Given such a
result, preparation of a heat exchanger (20) with the dimensions of
the present embodiment, without compromising good heat exchange
performance, enables to prevent damage to the pipe member (1) from
flying stones, such that a long product life can be maintained.
[0070] While in the present embodiment no soldering, gluing,
painting or the like is performed at the engagement portions (22)
of the fin members (3) and pipe member (1), in other differing
embodiments close adherence between the fin members (3) and pipe
member (1) may be effected by applying soldering, gluing, painting
or the like means at the engagement portions (22) and/or the
vicinity thereof. By bringing a fin member (3) and the pipe member
(1) into close adherence at an engagement portion (22) through the
above-mentioned means, situations where openings arise, moisture
enters into the openings and the fin member (3) and/or the pipe
member (1) corrode can be prevented, enabling an excellent
corrosion resistance to be obtained at this engagement portion
(22). Also, because the pipe member (1) and the fin member (3)
always maintain their state of close adherence, heat exchange
between the pipe member (1) and the fin member (3) is enabled to be
performed efficiently, such that a further improvement in heat
exchange performance becomes possible.
* * * * *